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Meniscal Allograft Transplantation After Total Meniscectomy of Torn Discoid Lateral Meniscus
Meniscal Allograft Transplantation After Total Meniscectomy of Torn Discoid Lateral Meniscus Jong-Min Kim, M.D., and Seong-Il Bin, M.D.
Purpose: The purpose of this study was to evaluate the short- to intermediate-term results of meniscal allograft transplantation after total meniscectomy of torn discoid lateral menisci, which are usually wider and thicker than normal lateral menisci. Methods: Between 1996 and 2003, 14 meniscal allografts were implanted in 14 patients with a previous total or near-total resection of torn discoid lateral menisci. All patients had a minimum of 21 months of follow-up, with a mean of 58 months. Osteochondritis dissecans was present in 3 cases, and osteochondral autograft transfer was performed in those cases. All patients were evaluated with the modified Lysholm scoring system. Postoperative magnetic resonance imaging was performed in 13 cases, and second-look arthroscopy was performed in 6. Results: Symptoms improved in all cases, and the modified Lysholm score increased on average from 71.4 preoperatively to 91.4 postoperatively. Postoperative magnetic resonance imaging showed secure integration of meniscal allograft in general. The 6 second-look arthroscopies revealed 4 normal menisci, 1 meniscus with anterior horn shrinkage, and 1 meniscus with a tear at the posterior horn of the allograft. Conclusions: The short- to intermediate-term results confirmed noteworthy clinical improvements and consistent objective findings. Meniscal allograft transplantation after total meniscectomy of torn discoid lateral menisci could be a reasonable treatment option in symptomatic patients. Nevertheless, long-term observation would be required to evaluate the longevity of these results. Level of Evidence: Level IV, therapeutic case series. Key Words: Discoid lateral meniscus—Meniscal allograft transplantation.
S
ince Milachowski et al.1 implanted the first human meniscal allograft in 1989, thousands of meniscal allograft transplantations have been performed and reported on in the literature. Most of the reported results showed predictable relief of pain and improve-
From the Department of Orthopedic Surgery, Kangbuk Samsung Hospital, Sungkyunkwan University School of Medicine (J.M.K.); and Department of Orthopedic Surgery, University of Ulsan, College of Medicine, Asan Medical Center (S.I.B.), Seoul, South Korea. The authors report no conflict of interest. Address correspondence and reprint requests to Seong-Il Bin, M.D., Department of Orthopedic Surgery, University of Ulsan, College of Medicine, Asan Medical Center, 388-1, Poongnapdong, Songpa-gu, Seoul, 138-736, South Korea. E-mail: sibin@ amc.seoul.kr © 2006 by the Arthroscopy Association of North America 0749-8063/06/2212-5417$32.00/0 doi:10.1016/j.arthro.2006.07.048 Note: To access the supplementary tables accompanying this report, visit the December issue of Arthroscopy at www. arthroscopyjournal.org.
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ment of knee function in the short- to intermediate-term follow-up.2-9 Given the relatively recent application of this procedure, the long-term chondroprotective effect of meniscal allograft transplantation that is expected to prevent or decelerate further degenerative changes has not been sufficiently documented so far. A discoid lateral meniscus is not an uncommon congenital anomaly in Korea and Japan, with a reported incidence rate of 15% to 17%.10-12 Not only the width but also the thickness of a discoid lateral meniscus is usually greater than that of a normal lateral meniscus. A discoid lateral meniscus is known to be prone to tear even without substantial trauma. Sometimes, it is inevitable to resect almost the whole discoid lateral meniscus because of the complexity and immensity of the tear configuration, leaving a scanty, nonfunctional rim. The expected results of total lateral meniscectomy in the long term are disastrous because the lateral compartment of the knee joint is well known to be more vulnerable to meniscal deficiency than the medial compartment and more readily leads
Arthroscopy: The Journal of Arthroscopic and Related Surgery, Vol 22, No 12 (December), 2006: pp 1344-1350
TORN DISCOID LATERAL MENISCUS to degenerative arthritis.13,14 Encouraged by the relatively consistent and fair early results of conventional meniscal allograft transplantation, the senior author (S-I.B.) decided to implant allograft menisci in patients who had undergone total resection of torn discoid lateral menisci in an attempt to diminish pain, improve knee function, and hopefully, to prevent or delay the degenerative process. To our knowledge, this is the first study of meniscal transplantation after total or subtotal meniscectomy of torn discoid lateral menisci. In this study we present and analyze the short- to intermediate-term results of meniscal allograft transplantation after total meniscectomy of torn discoid lateral menisci. We hypothesized that meniscal allograft transplantation would reduce knee pain and improve overall knee function without serious complications. METHODS From December 1996 through December 2003, 15 lateral meniscal allograft transplantations in 15 patients were performed. All surgical procedures were done by a single surgeon (S-I.B.). Each patient had undergone a near-total or total lateral meniscectomy for a torn discoid lateral meniscus before transplantation. Of the patients, 14 were available for follow-up evaluation more than 1 year after surgery and were included in this study (11 male and 3 female patients). The mean age of the patients at transplantation was 27.9 years, with a range of 17 to 41 years. The mean time from meniscectomy to transplantation was 10.5 months, with a range of 1 to 21 months. To identify appropriate candidates for meniscal allograft transplantation, a thorough history was obtained, a physical examination was performed, and proper imaging techniques were used in each patient. The indications for meniscal allograft transplantation were persistent swelling and lateral compartmental pain during activities of daily living after total meniscectomy. The contraindications consisted of generalized degenerative arthritis, uncorrected instability, axial limb malalignment, skeletal immaturity, and age over 45 years. Grafts were sized via anteroposterior and lateral radiographs allowing for magnification. Cryopreserved meniscal allograft was implanted via the trough method in the first 2 transplantations, and fresh-frozen meniscal allograft was implanted via the keyhole technique in the other 12 cases. After arthroscopic debridement and trimming of native meniscal remnant to prepare the fresh, bleeding bed, small lateral parapatellar arthrotomy was used for anterior
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meniscal rim trimming, creation of a bone tunnel, and graft passage. A small posterolateral incision was then used to expose the posterolateral joint capsule located just anterior to the lateral head of the gastrocnemius. Two No. 2 braided, nonabsorbable passing sutures that were anchored at the most posterior portion of the meniscal transplant before insertion were passed through the posterior capsule by use of the posterolateral incision and tied just beneath the capsule after insertion of the allograft. The anterior horn of the meniscal allograft was sutured to the anterior capsule under direct visualization, and the remaining portion of the meniscal allograft was secured by use of the arthroscopic inside-out technique with 7 to 10 No. 2 nonabsorbable sutures. In 3 patients osteochondritis dissecans was found in the weight-bearing portion of the lateral femoral condyle, and osteochondral autograft transfer was performed at the time of total meniscectomy in 1 case, concomitantly with meniscal allograft transplantation in 1, and 18 months after transplantation in 1. The mean length of follow-up was 58.1 months, with a range of 21 to 105 months. Postoperatively, a meticulous physical examination and modified Lysholm scoring system15 were used to evaluate clinical improvements, and data were analyzed by use of the paired-samples t test. Our routine preoperative and follow-up radiographs have consisted of standing anteroposterior, 45° flexion weight-bearing posteroanterior, lateral, and Merchant views since 1996. Preoperative and postoperative 45° flexion weight-bearing posteroanterior computed radiographs were available in 11 patients without magnification markers, and the shortest distances between the lateral femoral condyle and lateral tibial plateau were measured and compared with each other to identify joint space narrowing. Thirteen patients underwent magnetic resonance imaging (MRI) and were assessed in terms of effusion, general morphology and degeneration of the graft, presence of tearing, status of the articular cartilage, and peripheral displacement at the midzone or body of the allograft. Degeneration of the meniscal allograft was graded according to the criteria of Stoller et al.16 Second-look arthroscopy was performed in 6 patients to identify graft survival, shrinkage, tearing, and status of the articular cartilage.
RESULTS Postoperatively, all patients recovered full range of motion and any discomfort in activities of daily living
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J-M. KIM AND S-I. BIN were recorded, as was the status of the articular cartilage. Peripheral displacement of the transplant, which intersected both tibial intercondylar eminences, was measured on coronal images and was determined as the distance between the most peripheral portion of the transplant and the imaginary line connecting the lateral bony margin of the lateral femoral condyle and lateral tibial plateau, excluding spurs. The results of MRI were reviewed by a single musculoskeletal radiologist who was blinded to the patients’ information (Table 1, online only, available at www.arthroscopyjournal.org). All meniscal allografts showed sound peripheral healing to the joint capsule with various internal signal intensity changes (Fig 1). A radial tear at the posterior horn attachment site, however, was seen on the coronal fast spin-echo image in 1 case (Fig 2), and subsequent second-look arthroscopy was performed. The mean peripheral displacement of the transplant was 2.6 ⫾ 1.7 mm (range, 0 to 6.2 mm). There was no frank extrusion of the allograft out of the tibiofemoral joint. Six patients underwent second-look arthroscopy, and the mean time between meniscal allograft trans-
FIGURE 1. The MRI scan 13 months after transplantation showed secure integration of the allograft to the joint capsule and good positioning in relation to the tibiofemoral joint.
was alleviated. The modified Lysholm score increased in all cases after meniscal allograft transplantation, and the mean preoperative modified Lysholm score was 71.4 (range, 60 to 88), which increased to 91.4 (range, 82 to 100) at the last follow-up (P ⬍ .01). The radiographic joint space measurements were performed to evaluate progression of degenerative arthritis objectively. The joint spaces on preoperative radiographs were compared with those on radiographs obtained at the last follow-up. The mean preoperative joint space was 4.0 ⫾ 1.0 mm (range, 2.1 to 5.7 mm), and the mean joint space at last follow-up was 4.4 ⫾ 1.1 mm (range, 3.2 to 6.8 mm). However, the difference was not statistically significant (P ⫽ .29). The mean time from meniscal allograft transplantation to MRI examination was 13.5 months. Various magnetic susceptibility artifacts were present in 13 postoperative MRI examinations, which made interpretation in detail difficult. Joint effusion was rated as none, mild, moderate, or large. General morphology was observed with attention to the gross volume of the allograft and any presence of shrinkage. Degenerative changes in the allograft and the presence of tearing
FIGURE 2. The coronal fast spin-echo T2-weighted MRI 11 months after transplantation showed a radial tear at the posterior horn of the allograft.
TORN DISCOID LATERAL MENISCUS
FIGURE 3. The same patient in Fig 1 underwent second-look arthroscopy 16 months after transplantation, and normal contour of the allograft with sound peripheral healing was observed.
plantation and second-look arthroscopy was 13.7 months (range, 8 to 18 months). At second-look arthroscopy, the gross appearance of the allograft, areas of shrinkage or degeneration, stability of peripheral incorporation to the joint capsule, and presence of tearing were assessed (Table 2, online only, available at www.arthroscopyjournal.org). Stable peripheral healing and relatively good positioning of the allograft in relation to alignment of the tibiofemoral joint were observed in all cases (Fig 3), and obvious shrinkage at the anterior horn of the allograft was seen in 1 case (Fig 4). No progression of articular cartilage degeneration by more than 1 grade according to the Outerbridge classification was noted when compared with the status at the index surgery. In addition, an obvious
FIGURE 4. Anterior horn shrinkage was observed during secondlook arthroscopy in 1 case.
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FIGURE 5. The same patient in Fig 2 underwent second-look arthroscopy 13 months after transplantation. An obvious radial tear was seen at the posterior horn of the allograft.
radial tear at the posterior horn attachment site of the allograft was identified in 1 case, and subsequent partial meniscectomy was performed (Fig 5). On the basis of the definition of graft failure as a tear or incomplete healing to the joint capsule, the overall rate of graft survival was 92.9% in this study. No other complications were found in our series. DISCUSSION The meniscus plays essential roles in the biomechanics of the knee joint in terms of load transmission, shock absorption, joint lubrication, nutrition, and stability.14,17-20 There have been numerous studies that highlighted the possible harmful effects of meniscectomy.13,21-24 In contrast to the medial meniscus, the lateral meniscus is known to play an insignificant role in joint stability, but detrimental degenerative arthritis develops more readily in the absence of the lateral meniscus than the medial meniscus because the lateral meniscus plays a more important role in load transmission than the medial meniscus.13,14,18,19 Furthermore, total or subtotal meniscectomy is not an uncommon treatment in cases of torn discoid menisci comprising 29.6% according to one report.10 As for symptomatic discoid lateral menisci, total meniscectomy was the preferred treatment in the early era.25-27 However, long-term harmful effects of total meniscectomy were reported, and subsequently, partial meniscectomy has been the mainstay of the treatment options whenever possible.28-30 Whereas total meniscectomy is often reported to result in rapid pro-
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gression of degenerative arthritis over time, the results of partial meniscectomy are known to be more benign even in discoid lateral menisci. Partial meniscectomy or meniscoplasty of a torn discoid lateral meniscus eventually creates a nearly normally shaped meniscus that is much different from the original shape of the premorbid discoid lateral meniscus in terms of width and thickness. Especially in the case of a horizontal tear of a discoid lateral meniscus, the resultant meniscus after partial and conservative meniscectomy resembles the normal lateral meniscus,31 which also can be reproduced with lateral meniscal allograft transplantation. The good results of partial and conservative meniscectomy of torn discoid lateral menisci encouraged the senior author to decide to perform meniscal allograft transplantations in cases of total or near-total meniscectomies of torn discoid lateral menisci. Noyes et al.4 described the results of 40 cryopreserved allografts implanted into 38 patients who were evaluated at a mean of 40 months. Osteochondral autograft transfer procedures were done in 16 knees, and knee ligament reconstructions were performed in 9. The authors established categories of allograft classification composed of MRI evaluation, clinical examination, and follow-up arthroscopy and regarded a case as a failure if any one of the categories was rated as having failed. Because of those strict criteria for failure, the reported failure rate was 28%. It is remarkable that 89% of their patients rated the knee condition as improved after surgery. As the authors pointed out, no correlation was found between allograft characteristics and scores for patient perception of the knee condition. Yoldas et al.9 presented an analysis of 34 meniscal allografts with a mean follow-up of 2.9 years. Twenty meniscal allograft transplantations were combined with anterior cruciate ligament reconstruction. With the exception of 1 patient, all of their patients reported improvement, and the knee function and level of activity were normal or nearly normal. Joint space in the involved compartment was measured with a digital micrometer allowing for magnification. For those patients who underwent transplantation of the medial meniscus, the medial compartment measured 4.9 ⫾ 1.2 mm preoperatively and 5.2 ⫾ 1.5 mm postoperatively. For those who underwent transplantation of the lateral meniscus, the lateral compartment measured 4.1 ⫾ 1.8 mm preoperatively and 4.9 ⫾ 1.4 mm postoperatively. These increases, however, were not statistically significant.
Wirth et al.8 reviewed that cases of 23 patients who underwent medial meniscus allograft transplantation combined with anterior cruciate ligament reconstruction with a minimum follow-up of 14 years, which is the longest follow-up ever reported. A lyophilized allograft was used in 17 cases, and a deep-frozen allograft was used in the other 6. The deep-frozen meniscal allograft group presented superior results compared with the lyophilized meniscal allograft group in terms of clinical results, radiographic evaluation, arthroscopy results, and MRI evaluation. MRI evaluation showed good preservation of the deepfrozen meniscal allograft even after 14 years. However, there was a deterioration of clinical results during the follow-up period over time. Most of reported series have been associated with other concomitant procedures such as anterior cruciate ligament reconstruction or osteochondral autograft transfer, which made it difficult to compare their results. This is not surprising because a serious injury that made total meniscectomy unavoidable would probably also cause other substantial damage, such as osteochondral defects or torn cruciate ligaments. Our study also included 3 cases associated with an osteochondral autograft transfer procedure; nevertheless, we think of our study as one containing relatively isolated cases, reflecting that there seldom have been studies dealing with cases associated with other injuries to such a limited extent. In the 3 cases with osteochondritis dissecans, osteochondral autograft transfer was performed at the time of total meniscectomy in 1 and concurrently with meniscal allograft transplantation in 1. The lesion was left alone in the remaining case because it was small in size at the time of meniscal allograft transplantation. During secondlook arthroscopy, however, the lesion had progressed to being larger and deeper, which necessitated an osteochondral autograft transfer procedure. All 3 autografts were observed to be well healed on postoperative MRI evaluation without any complications. In this study 11 patients underwent radiographic examination with computed radiography under the same conditions without calibration by use of magnification markers. Although we did not correct the rate of magnification, the erroneous difference would be negligible, considering that all radiographs were obtained by use of the same standardized protocol and the usual rate of magnification was so small when the standard technique of plain radiography was used. Hence we decided to measure the distance and use it as an indicator of the height of the joint space, although it could not be the real height in and of itself.
TORN DISCOID LATERAL MENISCUS Although a statistically significant difference was not found, we believe that the increment of the joint space at least suggested that there was no rapid destruction of the articular cartilage. With more accurate measurement and longer follow-up, we believe that the height of the joint space would be a useful and convenient parameter of joint preservation after meniscal allograft transplantation. The value of objective evaluations such as postoperative MRI or second-look arthroscopy cannot be overestimated, because subjective evaluations, such as various scoring systems and improvement of symptoms, do not truly reflect the effect of meniscal allograft transplantation as a result of the different conditions in reported studies and, thus, are not credible indicators. MRI examination turned out to be quite useful because it was well correlated with findings of second-look arthroscopy, such as anterior horn shrinkage and the presence of tearing in the allograft. It enabled us to recognize a case with a tear at the posterior horn that otherwise would have been impossible. We have a firm belief that the results of meniscal allograft transplantation should be based on objective evaluation to judge its efficacy and survival. We tried to perform both postoperative MRI examination and second-look arthroscopy routinely in every case, but it was not so feasible because of the high cost. Moreover, second-look arthroscopy was an invasive procedure that required anesthesia and several days of admission; therefore patients were unwilling to undergo that procedure. Because the senior author found a reliable correlation between postoperative MRI examination and second-look arthroscopy after the first 6 cases examined, routine and invasive second-look arthroscopy was ceased and substituted by MRI examination alone. Although the resultant meniscus after meniscal allograft transplantation resembles the normal lateral meniscus, it is not exactly the same as the normal lateral meniscus. Meniscal allograft transplantation only provides healing of meniscal tissue to the joint capsule and does not reproduce the coronary ligament, which connects meniscal tissue to the tibial plateau. Perhaps this could be one of the reasons why meniscal displacement is so frequently observed on coronal MRI sections after meniscal allograft transplantation. Hence we cannot reproduce the result of partial meniscectomy with meniscal allograft transplantation. Furthermore, all patients who underwent total meniscectomy for torn discoid lateral menisci did no present with the same clinical symptoms. During the same period of this study, we performed total or near-total
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meniscectomy for torn discoid lateral menisci in 70 cases. In most of these there was remarkable pain relief and improvement of symptoms without compelling secondary procedures, and meniscal allograft transplantation was necessary in only 15 cases. The reasons why the patients showed different outcomes are unclear. We may assume some explanations, but this requires another prospective cohort study and is beyond the scope of this study. Given the previously mentioned considerations, we do not agree with the idea that meniscal allograft transplantation is necessary in all patients undergoing total meniscectomy for torn discoid menisci. On the basis of long-term results after total meniscectomy, this procedure is well known to result in detrimental degenerative arthritis, but we believe that this cannot justify routine meniscal allograft transplantation after total meniscectomy for a torn discoid meniscus because the longterm chondroprotective effect of meniscal allograft transplantation has not been sufficiently documented yet. For now, however, meniscal allograft transplantation is one of the best options that an orthopaedic surgeon can choose for a symptomatic patient after total meniscectomy to relieve pain and improve symptoms. Given the definition of graft failure as a tear or incomplete healing to the joint capsule, the rate of graft survival was 92.9% in this study. The male patient with a tear at the posterior horn of the allograft was aged 41 and was the oldest patient in our series. After meniscal allograft transplantation, he was doing well without symptoms and was enjoying light sporting activities such as golf. Eleven months after transplantation, he underwent a routine postoperative MRI examination, which revealed a radial tear at the posterior horn attachment site of the meniscal allograft. Although he complained of no clinical symptoms, subsequent second-look arthroscopy was performed, and a deep radial tear was identified at the posterior horn. A partial meniscectomy was performed in a routine manner. Contrary to our expectation, some slight pain when climbing stairs and after long-distance walking developed, and his final modified Lysholm score decreased to 89 after partial meniscectomy. Nevertheless, he had no severe discomfort in activities of daily living and still enjoyed playing golf. It is interesting, however, that he had been doing better even in the presence of a tear in the allograft, and subsequent partial meniscectomy made his symptoms slightly worse. We cautiously hypothesize that even a torn allograft may play some role as a spacefiller or an interposition in the tibiofemoral joint, but
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long-term follow-up of larger number of patients would be necessary to prove this hypothesis. To our knowledge, this is the first study of meniscal transplantation after total or subtotal meniscectomy of torn discoid lateral menisci. All of the patients underwent either MRI examination or second-look arthroscopy (or both) postoperatively as objective evaluations. In addition, relatively isolated cases of meniscal allograft transplantation were included in this study, although 3 cases were associated with osteochondritis dissecans in the lateral femoral condyle. These are considered to be the strengths of this study. The weaknesses of this study are the insufficient follow-up duration and the small number of patients; in addition, this was a retrospective study with no cohort. There were also some confounding variables, including the 3 cases of associated osteochondritis dissecans and the use of allografts that were processed differently (i.e., cryopreserved and fresh-frozen). CONCLUSIONS This study showed relatively good results regarding improvement in clinical symptoms, allograft survival, and prevention of degenerative arthritis with short- to intermediate-term follow-up. Although long-term follow-up of larger number of patients would be necessary to judge the adequacy and chondroprotective effect of meniscal allograft transplantation after total meniscectomy of torn discoid lateral menisci, short- to intermediate-term follow-up showed encouraging results. REFERENCES 1. Milachowski KA, Weismeier K, Wirth CJ. Homologous meniscus transplantation: Experimental and clinical results. Int Orthop 1989;13:1-11. 2. Garrett JC, Steensen RN. Meniscal transplantation in the human knee: A preliminary report. Arthroscopy 1991;7:57-62. 3. Graf KW Jr, Sekiya JK, Wojtys EM. Long-term results after combined medial meniscal allograft transplantation and anterior cruciate ligament reconstruction: Minimum 8.5-year follow-up study. Arthroscopy 2004;20:129-140. 4. Noyes FR, Barber-Westin SD, Rankin M. Meniscal transplantation in symptomatic patients less than fifty years old. J Bone Joint Surg Am 2004;86:1392-1404. 5. Shelton WR, Treacy SH, Dukes AD, Bomboy AL. Use of allografts in knee reconstruction: I. Basic science aspect and current status. J Am Acad Orthop Surg 1998;6:165-168. 6. Stollsteimer GT, Shelton WR, Dukes A, Bomboy AL. Meniscal allograft transplantation: A 1- to 5-year follow up of 22 patients. Arthroscopy 2000;16:343-347. 7. Van Arkel ER, de Boer HH. Human meniscal transplantation: Preliminary results at 2 to 5-year follow up. J Bone Joint Surg Br 1995;77:589-595.
8. Wirth CJ, Peters G, Milachowski KA, Weismeier KG, Kohn D. Long-term results of meniscal allograft transplantation. Am J Sports Med 2002;30:174-181. 9. Yoldas EA, Sekiya JK, Irrgang JJ, Fu FH, Harner CD. Arthroscopically assisted meniscal allograft transplantation with and without combined anterior cruciate ligament reconstruction. Knee Surg Sports Traumatol Arthrosc 2003;11:173-182. 10. Bin SI, Kim JC, Kim JM, Park SS, Han YK. Correlation between type of discoid lateral menisci and tear pattern. Knee Surg Sports Traumatol Arthrosc 2002;10:218-222. 11. Ikeuchi H. Arthroscopic treatment of the discoid lateral meniscus. Clin Orthop Relat Res 1982;19-28. 12. Seong SC, Park MJ. Analysis of the discoid meniscus in Koreans. Orthopedics 1992;15:61-65. 13. Fairbank TJ. Knee joint changes after meniscectomy. J Bone Joint Surg Br 1948;30:664-670. 14. Walker PS, Erkman MJ. The role of the menisci in force transmission across the knee. Clin Orthop Relat Res 1975;184-192. 15. Tegner Y, Lysholm J. Rating systems in the evaluation of knee ligaments injuries. Clin Orthop Relat Res 1985;43-49. 16. Stoller DW, Cannon WD, Anderson LJ. The knee. In: Stoller DW, ed. Magnetic resonance imaging in orthopaedics and sports medicine. Ed 2. Philadelphia: Lippincott Williams & Wilkins, 1997;203-442. 17. Barger WL, Moreland JR, Markolf KL, et al. In vivo stability testing of post-meniscectomy knees. Clin Orthop Relat Res 1989;247-252. 18. Levy IM, Torzilli PA, Gould JD, Warren RF. The effect of lateral meniscectomy on motion of the knee. J Bone Joint Surg Am 1989;71:401-406. 19. Levy IM, Torzilli PA, Warren RF. The effect of medial meniscectomy on anterior-posterior motion of the knee. J Bone Joint Surg Am 1982;64:883-888. 20. Radin EL, deLamotte F, Maquet P. Role of the meniscus in distribution of stress of the knee. Clin Orthop Relat Res 1984;290-294. 21. Johnson RJ, Kettelkamp DB, Clark W, Leaverton P. Factors effecting late results after meniscectomy. J Bone Join Surg Am 1974;56:719-729. 22. Jones RE, Smith EC, Reisch JS. Effects of medial meniscectomy in patients older than forty years. J Bone Joint Surg Am 1978;60:783-786. 23. Rockborn P, Messner K. Long-term results of meniscus repair and meniscectomy: A 13-year functional and radiographic follow-up study. Knee Surg Sports Traumatol Arthrosc 2000;8:2-10. 24. Jorgensen U, Sonne-Holm S, Lauridsen F, Rosenklint A. Long-term follow-up of meniscectomy in athletes. A prospective longitudinal study. J Bone Joint Surg Br 1987;69:80-83. 25. Ikeuchi H. Arthroscopic treatment of the discoid lateral meniscus. Technique and long-term results. Clin Orthop Relat Res 1982;19-28. 26. Hayashi LK, Yamaga H, Ida K, Miura T. Arthroscopic meniscectomy for discoid lateral meniscus in children. J Bone Joint Surg Am 1988;70:1495-1500. 27. Washington ER III, Root L, Liener UC. Discoid lateral meniscus in children: Long-term follow-up after excision. J Bone Joint Surg Am 1995;77:1357-1361. 28. Fujikawa K, Iseki F, Mikura Y. Partial resection of the discoid meniscus in the child’s knee. J Bone Joint Surg Br 1981;63: 391-395. 29. Pellacci F, Montanari G, Prosperi P, Galli G, Celli V. Lateral discoid meniscus: Treatment and results. Arthroscopy 1992;8: 526-530. 30. Raber DA, Friederich NF, Hefti F. Discoid lateral meniscus in children: Long-term follow-up after total meniscectomy. J Bone Joint Surg Am 1998;80:1579-1586. 31. Bin SI, Jeong SI, Kim JM, Shon HC. Arthroscopic partial meniscectomy for horizontal tear of discoid lateral meniscus. Knee Surg Sports Traumatol Arthrosc 2002;10:20-24.
TORN DISCOID LATERAL MENISCUS TABLE 1.
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Postoperative MRI Findings With Preoperative and Postoperative Modified Lysholm Score Degeneration (Grade)
Patient No.
Effusion
General Morphology
Anterior
Posterior
Lysholm Score Tear
1
Mild
Normal
0
1
None
2 3
— None
— 3
— 2
None
4
Mild
— Anterior horn subluxation without normal triangular shape Irregular shape of allograft
3
1
Moderate None None None None None Moderate None None None
Normal Normal Anterior horn shrinkage Small anterior horn Small anterior horn Invisible anterior horn Normal Normal Normal Normal
1 1 1 1 0 3 1 1 1 1
0 0 0 1 0 3 2 2 0 1
5 6 7 8 9 10 11 12 13 14
—
Radial tear at posterior horn None None None None None None None None None None
Cartilage
Preoperative
Postoperative
Small cartilage defect in LFC — Mild cartilage loss in LFC
64
90
64 71
90 82
No loss
69
89
No No No No No No No No No No
75 64 88 71 71 60 76 71 78 78
88 99 100 95 95 88 83 88 93 99
loss loss loss loss loss loss loss loss loss loss
NOTE. Patient numbers are listed in order of meniscal allograft transplantation, with lower numbers indicating earlier procedures. Abbreviation: LFC, lateral femoral condyle.
TABLE 2.
Findings at Second-Look Arthroscopy
Patient No.
General Appearance
Degeneration
Peripheral Healing
Tear
2 4 5 6 7 8
Normal Normal Normal Normal Anterior horn shrinkage Normal
Mild at midzone None None None None None
Stable Stable Stable Stable Stable Stable
None Radial tear at posterior horn None None None None
Purpose: The purpose of this study was to evaluate the short- to intermediate-term results of meniscal allograft transplantation after total meniscectomy of torn discoid lateral menisci, which are usually wider and thicker than normal lateral menisci. Methods: Between 1996 and 2003, 14 meniscal allografts were implanted in 14 patients with a previous total or near-total resection of torn discoid lateral menisci. All patients had a minimum of 21 months of follow-up, with a mean of 58 months. Osteochondritis dissecans was present in 3 cases, and osteochondral autograft transfer was performed in those cases. All patients were evaluated with the modified Lysholm scoring system. Postoperative magnetic resonance imaging was performed in 13 cases, and second-look arthroscopy was performed in 6. Results: Symptoms improved in all cases, and the modified Lysholm score increased on average from 71.4 preoperatively to 91.4 postoperatively. Postoperative magnetic resonance imaging showed secure integration of meniscal allograft in general. The 6 second-look arthroscopies revealed 4 normal menisci, 1 meniscus with anterior horn shrinkage, and 1 meniscus with a tear at the posterior horn of the allograft. Conclusions: The short- to intermediate-term results confirmed noteworthy clinical improvements and consistent objective findings. Meniscal allograft transplantation after total meniscectomy of torn discoid lateral menisci could be a reasonable treatment option in symptomatic patients. Nevertheless, long-term observation would be required to evaluate the longevity of these results. Level of Evidence: Level IV, therapeutic case series. Key Words: Discoid lateral meniscus—Meniscal allograft transplantation.
S
ince Milachowski et al.1 implanted the first human meniscal allograft in 1989, thousands of meniscal allograft transplantations have been performed and reported on in the literature. Most of the reported results showed predictable relief of pain and improve-
From the Department of Orthopedic Surgery, Kangbuk Samsung Hospital, Sungkyunkwan University School of Medicine (J.M.K.); and Department of Orthopedic Surgery, University of Ulsan, College of Medicine, Asan Medical Center (S.I.B.), Seoul, South Korea. The authors report no conflict of interest. Address correspondence and reprint requests to Seong-Il Bin, M.D., Department of Orthopedic Surgery, University of Ulsan, College of Medicine, Asan Medical Center, 388-1, Poongnapdong, Songpa-gu, Seoul, 138-736, South Korea. E-mail: sibin@ amc.seoul.kr © 2006 by the Arthroscopy Association of North America 0749-8063/06/2212-5417$32.00/0 doi:10.1016/j.arthro.2006.07.048 Note: To access the supplementary tables accompanying this report, visit the December issue of Arthroscopy at www. arthroscopyjournal.org.
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ment of knee function in the short- to intermediate-term follow-up.2-9 Given the relatively recent application of this procedure, the long-term chondroprotective effect of meniscal allograft transplantation that is expected to prevent or decelerate further degenerative changes has not been sufficiently documented so far. A discoid lateral meniscus is not an uncommon congenital anomaly in Korea and Japan, with a reported incidence rate of 15% to 17%.10-12 Not only the width but also the thickness of a discoid lateral meniscus is usually greater than that of a normal lateral meniscus. A discoid lateral meniscus is known to be prone to tear even without substantial trauma. Sometimes, it is inevitable to resect almost the whole discoid lateral meniscus because of the complexity and immensity of the tear configuration, leaving a scanty, nonfunctional rim. The expected results of total lateral meniscectomy in the long term are disastrous because the lateral compartment of the knee joint is well known to be more vulnerable to meniscal deficiency than the medial compartment and more readily leads
Arthroscopy: The Journal of Arthroscopic and Related Surgery, Vol 22, No 12 (December), 2006: pp 1344-1350
TORN DISCOID LATERAL MENISCUS to degenerative arthritis.13,14 Encouraged by the relatively consistent and fair early results of conventional meniscal allograft transplantation, the senior author (S-I.B.) decided to implant allograft menisci in patients who had undergone total resection of torn discoid lateral menisci in an attempt to diminish pain, improve knee function, and hopefully, to prevent or delay the degenerative process. To our knowledge, this is the first study of meniscal transplantation after total or subtotal meniscectomy of torn discoid lateral menisci. In this study we present and analyze the short- to intermediate-term results of meniscal allograft transplantation after total meniscectomy of torn discoid lateral menisci. We hypothesized that meniscal allograft transplantation would reduce knee pain and improve overall knee function without serious complications. METHODS From December 1996 through December 2003, 15 lateral meniscal allograft transplantations in 15 patients were performed. All surgical procedures were done by a single surgeon (S-I.B.). Each patient had undergone a near-total or total lateral meniscectomy for a torn discoid lateral meniscus before transplantation. Of the patients, 14 were available for follow-up evaluation more than 1 year after surgery and were included in this study (11 male and 3 female patients). The mean age of the patients at transplantation was 27.9 years, with a range of 17 to 41 years. The mean time from meniscectomy to transplantation was 10.5 months, with a range of 1 to 21 months. To identify appropriate candidates for meniscal allograft transplantation, a thorough history was obtained, a physical examination was performed, and proper imaging techniques were used in each patient. The indications for meniscal allograft transplantation were persistent swelling and lateral compartmental pain during activities of daily living after total meniscectomy. The contraindications consisted of generalized degenerative arthritis, uncorrected instability, axial limb malalignment, skeletal immaturity, and age over 45 years. Grafts were sized via anteroposterior and lateral radiographs allowing for magnification. Cryopreserved meniscal allograft was implanted via the trough method in the first 2 transplantations, and fresh-frozen meniscal allograft was implanted via the keyhole technique in the other 12 cases. After arthroscopic debridement and trimming of native meniscal remnant to prepare the fresh, bleeding bed, small lateral parapatellar arthrotomy was used for anterior
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meniscal rim trimming, creation of a bone tunnel, and graft passage. A small posterolateral incision was then used to expose the posterolateral joint capsule located just anterior to the lateral head of the gastrocnemius. Two No. 2 braided, nonabsorbable passing sutures that were anchored at the most posterior portion of the meniscal transplant before insertion were passed through the posterior capsule by use of the posterolateral incision and tied just beneath the capsule after insertion of the allograft. The anterior horn of the meniscal allograft was sutured to the anterior capsule under direct visualization, and the remaining portion of the meniscal allograft was secured by use of the arthroscopic inside-out technique with 7 to 10 No. 2 nonabsorbable sutures. In 3 patients osteochondritis dissecans was found in the weight-bearing portion of the lateral femoral condyle, and osteochondral autograft transfer was performed at the time of total meniscectomy in 1 case, concomitantly with meniscal allograft transplantation in 1, and 18 months after transplantation in 1. The mean length of follow-up was 58.1 months, with a range of 21 to 105 months. Postoperatively, a meticulous physical examination and modified Lysholm scoring system15 were used to evaluate clinical improvements, and data were analyzed by use of the paired-samples t test. Our routine preoperative and follow-up radiographs have consisted of standing anteroposterior, 45° flexion weight-bearing posteroanterior, lateral, and Merchant views since 1996. Preoperative and postoperative 45° flexion weight-bearing posteroanterior computed radiographs were available in 11 patients without magnification markers, and the shortest distances between the lateral femoral condyle and lateral tibial plateau were measured and compared with each other to identify joint space narrowing. Thirteen patients underwent magnetic resonance imaging (MRI) and were assessed in terms of effusion, general morphology and degeneration of the graft, presence of tearing, status of the articular cartilage, and peripheral displacement at the midzone or body of the allograft. Degeneration of the meniscal allograft was graded according to the criteria of Stoller et al.16 Second-look arthroscopy was performed in 6 patients to identify graft survival, shrinkage, tearing, and status of the articular cartilage.
RESULTS Postoperatively, all patients recovered full range of motion and any discomfort in activities of daily living
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J-M. KIM AND S-I. BIN were recorded, as was the status of the articular cartilage. Peripheral displacement of the transplant, which intersected both tibial intercondylar eminences, was measured on coronal images and was determined as the distance between the most peripheral portion of the transplant and the imaginary line connecting the lateral bony margin of the lateral femoral condyle and lateral tibial plateau, excluding spurs. The results of MRI were reviewed by a single musculoskeletal radiologist who was blinded to the patients’ information (Table 1, online only, available at www.arthroscopyjournal.org). All meniscal allografts showed sound peripheral healing to the joint capsule with various internal signal intensity changes (Fig 1). A radial tear at the posterior horn attachment site, however, was seen on the coronal fast spin-echo image in 1 case (Fig 2), and subsequent second-look arthroscopy was performed. The mean peripheral displacement of the transplant was 2.6 ⫾ 1.7 mm (range, 0 to 6.2 mm). There was no frank extrusion of the allograft out of the tibiofemoral joint. Six patients underwent second-look arthroscopy, and the mean time between meniscal allograft trans-
FIGURE 1. The MRI scan 13 months after transplantation showed secure integration of the allograft to the joint capsule and good positioning in relation to the tibiofemoral joint.
was alleviated. The modified Lysholm score increased in all cases after meniscal allograft transplantation, and the mean preoperative modified Lysholm score was 71.4 (range, 60 to 88), which increased to 91.4 (range, 82 to 100) at the last follow-up (P ⬍ .01). The radiographic joint space measurements were performed to evaluate progression of degenerative arthritis objectively. The joint spaces on preoperative radiographs were compared with those on radiographs obtained at the last follow-up. The mean preoperative joint space was 4.0 ⫾ 1.0 mm (range, 2.1 to 5.7 mm), and the mean joint space at last follow-up was 4.4 ⫾ 1.1 mm (range, 3.2 to 6.8 mm). However, the difference was not statistically significant (P ⫽ .29). The mean time from meniscal allograft transplantation to MRI examination was 13.5 months. Various magnetic susceptibility artifacts were present in 13 postoperative MRI examinations, which made interpretation in detail difficult. Joint effusion was rated as none, mild, moderate, or large. General morphology was observed with attention to the gross volume of the allograft and any presence of shrinkage. Degenerative changes in the allograft and the presence of tearing
FIGURE 2. The coronal fast spin-echo T2-weighted MRI 11 months after transplantation showed a radial tear at the posterior horn of the allograft.
TORN DISCOID LATERAL MENISCUS
FIGURE 3. The same patient in Fig 1 underwent second-look arthroscopy 16 months after transplantation, and normal contour of the allograft with sound peripheral healing was observed.
plantation and second-look arthroscopy was 13.7 months (range, 8 to 18 months). At second-look arthroscopy, the gross appearance of the allograft, areas of shrinkage or degeneration, stability of peripheral incorporation to the joint capsule, and presence of tearing were assessed (Table 2, online only, available at www.arthroscopyjournal.org). Stable peripheral healing and relatively good positioning of the allograft in relation to alignment of the tibiofemoral joint were observed in all cases (Fig 3), and obvious shrinkage at the anterior horn of the allograft was seen in 1 case (Fig 4). No progression of articular cartilage degeneration by more than 1 grade according to the Outerbridge classification was noted when compared with the status at the index surgery. In addition, an obvious
FIGURE 4. Anterior horn shrinkage was observed during secondlook arthroscopy in 1 case.
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FIGURE 5. The same patient in Fig 2 underwent second-look arthroscopy 13 months after transplantation. An obvious radial tear was seen at the posterior horn of the allograft.
radial tear at the posterior horn attachment site of the allograft was identified in 1 case, and subsequent partial meniscectomy was performed (Fig 5). On the basis of the definition of graft failure as a tear or incomplete healing to the joint capsule, the overall rate of graft survival was 92.9% in this study. No other complications were found in our series. DISCUSSION The meniscus plays essential roles in the biomechanics of the knee joint in terms of load transmission, shock absorption, joint lubrication, nutrition, and stability.14,17-20 There have been numerous studies that highlighted the possible harmful effects of meniscectomy.13,21-24 In contrast to the medial meniscus, the lateral meniscus is known to play an insignificant role in joint stability, but detrimental degenerative arthritis develops more readily in the absence of the lateral meniscus than the medial meniscus because the lateral meniscus plays a more important role in load transmission than the medial meniscus.13,14,18,19 Furthermore, total or subtotal meniscectomy is not an uncommon treatment in cases of torn discoid menisci comprising 29.6% according to one report.10 As for symptomatic discoid lateral menisci, total meniscectomy was the preferred treatment in the early era.25-27 However, long-term harmful effects of total meniscectomy were reported, and subsequently, partial meniscectomy has been the mainstay of the treatment options whenever possible.28-30 Whereas total meniscectomy is often reported to result in rapid pro-
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gression of degenerative arthritis over time, the results of partial meniscectomy are known to be more benign even in discoid lateral menisci. Partial meniscectomy or meniscoplasty of a torn discoid lateral meniscus eventually creates a nearly normally shaped meniscus that is much different from the original shape of the premorbid discoid lateral meniscus in terms of width and thickness. Especially in the case of a horizontal tear of a discoid lateral meniscus, the resultant meniscus after partial and conservative meniscectomy resembles the normal lateral meniscus,31 which also can be reproduced with lateral meniscal allograft transplantation. The good results of partial and conservative meniscectomy of torn discoid lateral menisci encouraged the senior author to decide to perform meniscal allograft transplantations in cases of total or near-total meniscectomies of torn discoid lateral menisci. Noyes et al.4 described the results of 40 cryopreserved allografts implanted into 38 patients who were evaluated at a mean of 40 months. Osteochondral autograft transfer procedures were done in 16 knees, and knee ligament reconstructions were performed in 9. The authors established categories of allograft classification composed of MRI evaluation, clinical examination, and follow-up arthroscopy and regarded a case as a failure if any one of the categories was rated as having failed. Because of those strict criteria for failure, the reported failure rate was 28%. It is remarkable that 89% of their patients rated the knee condition as improved after surgery. As the authors pointed out, no correlation was found between allograft characteristics and scores for patient perception of the knee condition. Yoldas et al.9 presented an analysis of 34 meniscal allografts with a mean follow-up of 2.9 years. Twenty meniscal allograft transplantations were combined with anterior cruciate ligament reconstruction. With the exception of 1 patient, all of their patients reported improvement, and the knee function and level of activity were normal or nearly normal. Joint space in the involved compartment was measured with a digital micrometer allowing for magnification. For those patients who underwent transplantation of the medial meniscus, the medial compartment measured 4.9 ⫾ 1.2 mm preoperatively and 5.2 ⫾ 1.5 mm postoperatively. For those who underwent transplantation of the lateral meniscus, the lateral compartment measured 4.1 ⫾ 1.8 mm preoperatively and 4.9 ⫾ 1.4 mm postoperatively. These increases, however, were not statistically significant.
Wirth et al.8 reviewed that cases of 23 patients who underwent medial meniscus allograft transplantation combined with anterior cruciate ligament reconstruction with a minimum follow-up of 14 years, which is the longest follow-up ever reported. A lyophilized allograft was used in 17 cases, and a deep-frozen allograft was used in the other 6. The deep-frozen meniscal allograft group presented superior results compared with the lyophilized meniscal allograft group in terms of clinical results, radiographic evaluation, arthroscopy results, and MRI evaluation. MRI evaluation showed good preservation of the deepfrozen meniscal allograft even after 14 years. However, there was a deterioration of clinical results during the follow-up period over time. Most of reported series have been associated with other concomitant procedures such as anterior cruciate ligament reconstruction or osteochondral autograft transfer, which made it difficult to compare their results. This is not surprising because a serious injury that made total meniscectomy unavoidable would probably also cause other substantial damage, such as osteochondral defects or torn cruciate ligaments. Our study also included 3 cases associated with an osteochondral autograft transfer procedure; nevertheless, we think of our study as one containing relatively isolated cases, reflecting that there seldom have been studies dealing with cases associated with other injuries to such a limited extent. In the 3 cases with osteochondritis dissecans, osteochondral autograft transfer was performed at the time of total meniscectomy in 1 and concurrently with meniscal allograft transplantation in 1. The lesion was left alone in the remaining case because it was small in size at the time of meniscal allograft transplantation. During secondlook arthroscopy, however, the lesion had progressed to being larger and deeper, which necessitated an osteochondral autograft transfer procedure. All 3 autografts were observed to be well healed on postoperative MRI evaluation without any complications. In this study 11 patients underwent radiographic examination with computed radiography under the same conditions without calibration by use of magnification markers. Although we did not correct the rate of magnification, the erroneous difference would be negligible, considering that all radiographs were obtained by use of the same standardized protocol and the usual rate of magnification was so small when the standard technique of plain radiography was used. Hence we decided to measure the distance and use it as an indicator of the height of the joint space, although it could not be the real height in and of itself.
TORN DISCOID LATERAL MENISCUS Although a statistically significant difference was not found, we believe that the increment of the joint space at least suggested that there was no rapid destruction of the articular cartilage. With more accurate measurement and longer follow-up, we believe that the height of the joint space would be a useful and convenient parameter of joint preservation after meniscal allograft transplantation. The value of objective evaluations such as postoperative MRI or second-look arthroscopy cannot be overestimated, because subjective evaluations, such as various scoring systems and improvement of symptoms, do not truly reflect the effect of meniscal allograft transplantation as a result of the different conditions in reported studies and, thus, are not credible indicators. MRI examination turned out to be quite useful because it was well correlated with findings of second-look arthroscopy, such as anterior horn shrinkage and the presence of tearing in the allograft. It enabled us to recognize a case with a tear at the posterior horn that otherwise would have been impossible. We have a firm belief that the results of meniscal allograft transplantation should be based on objective evaluation to judge its efficacy and survival. We tried to perform both postoperative MRI examination and second-look arthroscopy routinely in every case, but it was not so feasible because of the high cost. Moreover, second-look arthroscopy was an invasive procedure that required anesthesia and several days of admission; therefore patients were unwilling to undergo that procedure. Because the senior author found a reliable correlation between postoperative MRI examination and second-look arthroscopy after the first 6 cases examined, routine and invasive second-look arthroscopy was ceased and substituted by MRI examination alone. Although the resultant meniscus after meniscal allograft transplantation resembles the normal lateral meniscus, it is not exactly the same as the normal lateral meniscus. Meniscal allograft transplantation only provides healing of meniscal tissue to the joint capsule and does not reproduce the coronary ligament, which connects meniscal tissue to the tibial plateau. Perhaps this could be one of the reasons why meniscal displacement is so frequently observed on coronal MRI sections after meniscal allograft transplantation. Hence we cannot reproduce the result of partial meniscectomy with meniscal allograft transplantation. Furthermore, all patients who underwent total meniscectomy for torn discoid lateral menisci did no present with the same clinical symptoms. During the same period of this study, we performed total or near-total
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meniscectomy for torn discoid lateral menisci in 70 cases. In most of these there was remarkable pain relief and improvement of symptoms without compelling secondary procedures, and meniscal allograft transplantation was necessary in only 15 cases. The reasons why the patients showed different outcomes are unclear. We may assume some explanations, but this requires another prospective cohort study and is beyond the scope of this study. Given the previously mentioned considerations, we do not agree with the idea that meniscal allograft transplantation is necessary in all patients undergoing total meniscectomy for torn discoid menisci. On the basis of long-term results after total meniscectomy, this procedure is well known to result in detrimental degenerative arthritis, but we believe that this cannot justify routine meniscal allograft transplantation after total meniscectomy for a torn discoid meniscus because the longterm chondroprotective effect of meniscal allograft transplantation has not been sufficiently documented yet. For now, however, meniscal allograft transplantation is one of the best options that an orthopaedic surgeon can choose for a symptomatic patient after total meniscectomy to relieve pain and improve symptoms. Given the definition of graft failure as a tear or incomplete healing to the joint capsule, the rate of graft survival was 92.9% in this study. The male patient with a tear at the posterior horn of the allograft was aged 41 and was the oldest patient in our series. After meniscal allograft transplantation, he was doing well without symptoms and was enjoying light sporting activities such as golf. Eleven months after transplantation, he underwent a routine postoperative MRI examination, which revealed a radial tear at the posterior horn attachment site of the meniscal allograft. Although he complained of no clinical symptoms, subsequent second-look arthroscopy was performed, and a deep radial tear was identified at the posterior horn. A partial meniscectomy was performed in a routine manner. Contrary to our expectation, some slight pain when climbing stairs and after long-distance walking developed, and his final modified Lysholm score decreased to 89 after partial meniscectomy. Nevertheless, he had no severe discomfort in activities of daily living and still enjoyed playing golf. It is interesting, however, that he had been doing better even in the presence of a tear in the allograft, and subsequent partial meniscectomy made his symptoms slightly worse. We cautiously hypothesize that even a torn allograft may play some role as a spacefiller or an interposition in the tibiofemoral joint, but
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long-term follow-up of larger number of patients would be necessary to prove this hypothesis. To our knowledge, this is the first study of meniscal transplantation after total or subtotal meniscectomy of torn discoid lateral menisci. All of the patients underwent either MRI examination or second-look arthroscopy (or both) postoperatively as objective evaluations. In addition, relatively isolated cases of meniscal allograft transplantation were included in this study, although 3 cases were associated with osteochondritis dissecans in the lateral femoral condyle. These are considered to be the strengths of this study. The weaknesses of this study are the insufficient follow-up duration and the small number of patients; in addition, this was a retrospective study with no cohort. There were also some confounding variables, including the 3 cases of associated osteochondritis dissecans and the use of allografts that were processed differently (i.e., cryopreserved and fresh-frozen). CONCLUSIONS This study showed relatively good results regarding improvement in clinical symptoms, allograft survival, and prevention of degenerative arthritis with short- to intermediate-term follow-up. Although long-term follow-up of larger number of patients would be necessary to judge the adequacy and chondroprotective effect of meniscal allograft transplantation after total meniscectomy of torn discoid lateral menisci, short- to intermediate-term follow-up showed encouraging results. REFERENCES 1. Milachowski KA, Weismeier K, Wirth CJ. Homologous meniscus transplantation: Experimental and clinical results. Int Orthop 1989;13:1-11. 2. Garrett JC, Steensen RN. Meniscal transplantation in the human knee: A preliminary report. Arthroscopy 1991;7:57-62. 3. Graf KW Jr, Sekiya JK, Wojtys EM. Long-term results after combined medial meniscal allograft transplantation and anterior cruciate ligament reconstruction: Minimum 8.5-year follow-up study. Arthroscopy 2004;20:129-140. 4. Noyes FR, Barber-Westin SD, Rankin M. Meniscal transplantation in symptomatic patients less than fifty years old. J Bone Joint Surg Am 2004;86:1392-1404. 5. Shelton WR, Treacy SH, Dukes AD, Bomboy AL. Use of allografts in knee reconstruction: I. Basic science aspect and current status. J Am Acad Orthop Surg 1998;6:165-168. 6. Stollsteimer GT, Shelton WR, Dukes A, Bomboy AL. Meniscal allograft transplantation: A 1- to 5-year follow up of 22 patients. Arthroscopy 2000;16:343-347. 7. Van Arkel ER, de Boer HH. Human meniscal transplantation: Preliminary results at 2 to 5-year follow up. J Bone Joint Surg Br 1995;77:589-595.
8. Wirth CJ, Peters G, Milachowski KA, Weismeier KG, Kohn D. Long-term results of meniscal allograft transplantation. Am J Sports Med 2002;30:174-181. 9. Yoldas EA, Sekiya JK, Irrgang JJ, Fu FH, Harner CD. Arthroscopically assisted meniscal allograft transplantation with and without combined anterior cruciate ligament reconstruction. Knee Surg Sports Traumatol Arthrosc 2003;11:173-182. 10. Bin SI, Kim JC, Kim JM, Park SS, Han YK. Correlation between type of discoid lateral menisci and tear pattern. Knee Surg Sports Traumatol Arthrosc 2002;10:218-222. 11. Ikeuchi H. Arthroscopic treatment of the discoid lateral meniscus. Clin Orthop Relat Res 1982;19-28. 12. Seong SC, Park MJ. Analysis of the discoid meniscus in Koreans. Orthopedics 1992;15:61-65. 13. Fairbank TJ. Knee joint changes after meniscectomy. J Bone Joint Surg Br 1948;30:664-670. 14. Walker PS, Erkman MJ. The role of the menisci in force transmission across the knee. Clin Orthop Relat Res 1975;184-192. 15. Tegner Y, Lysholm J. Rating systems in the evaluation of knee ligaments injuries. Clin Orthop Relat Res 1985;43-49. 16. Stoller DW, Cannon WD, Anderson LJ. The knee. In: Stoller DW, ed. Magnetic resonance imaging in orthopaedics and sports medicine. Ed 2. Philadelphia: Lippincott Williams & Wilkins, 1997;203-442. 17. Barger WL, Moreland JR, Markolf KL, et al. In vivo stability testing of post-meniscectomy knees. Clin Orthop Relat Res 1989;247-252. 18. Levy IM, Torzilli PA, Gould JD, Warren RF. The effect of lateral meniscectomy on motion of the knee. J Bone Joint Surg Am 1989;71:401-406. 19. Levy IM, Torzilli PA, Warren RF. The effect of medial meniscectomy on anterior-posterior motion of the knee. J Bone Joint Surg Am 1982;64:883-888. 20. Radin EL, deLamotte F, Maquet P. Role of the meniscus in distribution of stress of the knee. Clin Orthop Relat Res 1984;290-294. 21. Johnson RJ, Kettelkamp DB, Clark W, Leaverton P. Factors effecting late results after meniscectomy. J Bone Join Surg Am 1974;56:719-729. 22. Jones RE, Smith EC, Reisch JS. Effects of medial meniscectomy in patients older than forty years. J Bone Joint Surg Am 1978;60:783-786. 23. Rockborn P, Messner K. Long-term results of meniscus repair and meniscectomy: A 13-year functional and radiographic follow-up study. Knee Surg Sports Traumatol Arthrosc 2000;8:2-10. 24. Jorgensen U, Sonne-Holm S, Lauridsen F, Rosenklint A. Long-term follow-up of meniscectomy in athletes. A prospective longitudinal study. J Bone Joint Surg Br 1987;69:80-83. 25. Ikeuchi H. Arthroscopic treatment of the discoid lateral meniscus. Technique and long-term results. Clin Orthop Relat Res 1982;19-28. 26. Hayashi LK, Yamaga H, Ida K, Miura T. Arthroscopic meniscectomy for discoid lateral meniscus in children. J Bone Joint Surg Am 1988;70:1495-1500. 27. Washington ER III, Root L, Liener UC. Discoid lateral meniscus in children: Long-term follow-up after excision. J Bone Joint Surg Am 1995;77:1357-1361. 28. Fujikawa K, Iseki F, Mikura Y. Partial resection of the discoid meniscus in the child’s knee. J Bone Joint Surg Br 1981;63: 391-395. 29. Pellacci F, Montanari G, Prosperi P, Galli G, Celli V. Lateral discoid meniscus: Treatment and results. Arthroscopy 1992;8: 526-530. 30. Raber DA, Friederich NF, Hefti F. Discoid lateral meniscus in children: Long-term follow-up after total meniscectomy. J Bone Joint Surg Am 1998;80:1579-1586. 31. Bin SI, Jeong SI, Kim JM, Shon HC. Arthroscopic partial meniscectomy for horizontal tear of discoid lateral meniscus. Knee Surg Sports Traumatol Arthrosc 2002;10:20-24.
TORN DISCOID LATERAL MENISCUS TABLE 1.
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Postoperative MRI Findings With Preoperative and Postoperative Modified Lysholm Score Degeneration (Grade)
Patient No.
Effusion
General Morphology
Anterior
Posterior
Lysholm Score Tear
1
Mild
Normal
0
1
None
2 3
— None
— 3
— 2
None
4
Mild
— Anterior horn subluxation without normal triangular shape Irregular shape of allograft
3
1
Moderate None None None None None Moderate None None None
Normal Normal Anterior horn shrinkage Small anterior horn Small anterior horn Invisible anterior horn Normal Normal Normal Normal
1 1 1 1 0 3 1 1 1 1
0 0 0 1 0 3 2 2 0 1
5 6 7 8 9 10 11 12 13 14
—
Radial tear at posterior horn None None None None None None None None None None
Cartilage
Preoperative
Postoperative
Small cartilage defect in LFC — Mild cartilage loss in LFC
64
90
64 71
90 82
No loss
69
89
No No No No No No No No No No
75 64 88 71 71 60 76 71 78 78
88 99 100 95 95 88 83 88 93 99
loss loss loss loss loss loss loss loss loss loss
NOTE. Patient numbers are listed in order of meniscal allograft transplantation, with lower numbers indicating earlier procedures. Abbreviation: LFC, lateral femoral condyle.
TABLE 2.
Findings at Second-Look Arthroscopy
Patient No.
General Appearance
Degeneration
Peripheral Healing
Tear
2 4 5 6 7 8
Normal Normal Normal Normal Anterior horn shrinkage Normal
Mild at midzone None None None None None
Stable Stable Stable Stable Stable Stable
None Radial tear at posterior horn None None None None