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Magnetic Resonance Imaging of the Patellar Tendon After Harvesting Its Central Third: A Comparison Between Traditional and Subcutaneous Harvesting Techniques
Magnetic Resonance Imaging of the Patellar Tendon After Harvesting Its Central Third: A Comparison Between Traditional and Subcutaneous Harvesting Techniques Ju¨ri Kartus, M.D., Sven Lindahl, M.D., Ph.D., Sven Stener, M.D., Bengt I. Eriksson, M.D., Ph.D., and Jon Karlsson, M.D., Ph.D.
Summary: The aim of this study was to compare the 2-year results after anterior cruciate ligament reconstruction using patellar tendon autografts harvested through a paratenon-splitting, traditional technique (group A) with the results of a subcutaneous technique aiming at protecting the infrapatellar nerves and the paratenon (group B). Special emphasis was placed on evaluating the donor site. Magnetic resonance imaging (MRI) of the patellar tendon was performed to evaluate the reconstitution after harvesting its central third. Examinations of knee-walking ability and assessments of anterior knee sensitivity were made in order to evaluate donor-site discomfort and the function of infrapatellar nerves. Seventy-two consecutive patients were included in the study; group A comprised 35 patients and group B, 37 patients. At the 2-year follow-up, the Tegner activity level, the Lysholm score, and the IKDC evaluation system showed no significant differences between groups A and B. The median loss of normal anterior knee sensitivity was 16 cm2 (range, 0 to 200 cm2) in group A and 0 cm2 (range, 0 to 285 cm2) in group B (P ⫽ .20). In group A 20% of the patients and in group B 58% had normal sensitivity (P ⬍ .01). MRI showed that the donor-site gap (area corresponding to non–tendinous-like tissue signal) was 5 mm (range, 0 to 9 mm) in group A and 2 mm (range, 0 to 5 mm) in group B (P ⬍ .0001). At 2-year follow-up, the subcutaneous graft-harvesting technique resulted in less disturbance of anterior knee sensitivity and a smaller donor-site gap than the traditional technique. Key Words: Anterior cruciate—Patellar ligament—Magnetic resonance imaging— Donor-site—Harvesting technique.
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onor-site morbidity is reported in 40% to 60% of patients after anterior cruciate ligament reconstruction using patellar tendon autograft.1 Most evaluations
From the Department of Orthopaedics (J.K., S.S.) and Diagnostic Radiology (S.L.), Norra A¨lvsborg Hospital; and the Department of Orthopaedics, Sahlgrens University Hospital (B.I.E., J.K.), Go¨teborg, Sweden. Supported by grants from the Research and Development Department of Northern A¨lvsborg and the Swedish National Centre for Research in Sports. Address correspondence and reprint requests to Ju¨ri Kartus, M.D., Department of Orthopaedics, Norra A¨lvsborgs Hospital, SE-461 85 Trollha¨ttan, Sweden. E-mail: juri.kartus@trollhattan. mail.telia.com r 1999 by the Arthroscopy Association of North America 0749-8063/99/1506-1961$3.00/0
of donor-site morbidity do not assess the patellar tendon itself, but rather the secondary symptoms that occur. Symptoms such as local tenderness, dysesthesia, anterior knee pain, stiffness, and inability to kneel and knee-walk have all been described after central patellar tendon harvest or after incisions in the anterior knee region.2-7 It is now understood that there is no advantage in closing the donor-site after harvesting its central third.8,9 Probably as a result of an inflammatory reaction, the remaining two thirds of the patellar tendon undergo an increase in cross-sectional area that appears to be persistent, at least up to 24 months after the harvest, as has been shown by several investiga-
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tors.5,10-13 Whether the patellar tendon is able to regenerate after harvesting its central third is controversial. Rosenberg et al.14 stated that the donor site displays significant scar formation and persistent defects 12 to 24 months after the harvest, when examined using both computed tomography (CT) and magnetic resonance imaging (MRI). However, both Nixon et al.15 and Berg12 claim that the central tendon defect heals as assessed by MRI and histological examination. Weinstabl et al.16 have shown that the blood supply to the patellar tendon passes through the paratenon. In a dissection study of cadaver and amputated specimens, we have shown that it is possible to harvest the central third of the patellar tendon through two 25-mm vertical incisions, leaving the infrapatellar nerves and the paratenon partially intact in the majority of specimens.17 Theoretically, the healing of the donor-site gap might occur more rapidly if the paratenon were left intact and the disturbance of anterior knee sensitivity might be less if the integrity of the infrapatellar nerves were respected. The hypothesis of this study was that patellar tendon harvest using the subcutaneous technique produces less disturbance of anterior knee sensitivity and a more complete healing of the donor-site gap than the traditional technique. PATIENTS AND METHODS Seventy-two patients who underwent anterior cruciate ligament reconstruction in a consecutive prospective series and at the 2-year follow-up agreed to undergo an MRI evaluation were included in the study. Group A comprised 35 consecutive patients (12 female and 23 male) who had previously had their patellar tendon harvested through a single vertical paratenon-splitting 70-mm skin incision. Group B comprised 37 consecutive patients (12 female and 25 male) who had had their patellar tendon harvested through two vertical 25-mm skin incisions.17 The average age of the patients at the time of the index operation was 26 years (range, 14 to 44 years) in group A and 27 years (range, 14 to 50 years) in group B (not significant). The time between the injury and the index operation was 15 months (range, 1 to 168 months) in group A and 12 months (range, 2 to 192 months) in group B (not significant). The preinjury Tegner level of activity18 was 9 (range, 4-9) in group A and 9 (range, 5-9) in group B (not significant). An independent observer performed all the fol-
low-up examinations after 24 months (range, 22 to 29 months) in group A and 25 months (range, 23 to 29 months) in group B. The follow-up was based on the Lysholm score18, the Tegner activity level,18 and the IKDC evaluation system.19 The functional performance was evaluated using the one-leg hoptest.19 Special attention was paid to the anterior knee region. The skin was palpated by touch of the examiners fingers and the area of lost or disturbed anterior knee sensitivity was measured in square centimeters. The kneeling and knee-walking ability was tested and subjectively classified by the patient as normal, unpleasant, difficult, or impossible.5,6 The patients were classified as having subjective anterior knee pain if the pain was related to activity, stair walking, and sitting with their knees flexed at 90°. Surgical Technique All the patients had their ligament injury reconstructed by one experienced arthroscopic surgeon using patellar tendon autograft. A standard oneincision technique was used with the femoral interference screw inserted through the anterior portal and the tibial interference screw from the outside. In group A, the patellar tendon was harvested through a 70-mm skin incision, the paratenon was split along its entire length, and no effort was made to isolate and spare the infrapatellar nerves. At the end of the surgical procedure, the tendon defect was left open and the paratenon was closed as meticulously as possible. In group B, the patellar tendon was harvested through two 25-mm vertical skin incisions, tunneling the graft subcutaneously and under the paratenon with the aim of leaving the major part of the paratenon closed and the infrapatellar nerves intact, as described in the report of a previous dissection study also published in this issue (Fig 1).17 At the end of the procedure, the two small incisions in the paratenon were closed as meticulously as possible. Rehabilitation The patients in both groups were rehabilitated according to an identical protocol with immediate full range of motion, full weight-bearing, and early closedchain exercises.20 A rehabilitation brace was not used with the exception of nine patients in group A.21 Running was permitted at 3 months and contact sports at 6 months. MRI Examination One independent radiologist without any knowledge of the primary treatment made all the radio-
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FIGURE 1. In group B, the patellar tendon was harvested through two 25-mm vertical skin incisions, tunneling the graft subcutaneously and under the paratenon, with the aim of leaving the major part of the paratenon undamaged and the infrapatellar nerves intact.
graphic assessments. The patients in group A and group B were examined 27 months (range, 22 to 38 months) and 27 months (range, 24 to 29 months) months, respectively, after the index operation. A Siemens Magnetom 1.0 Tesla (Siemens, Erlangen, Germany) and a flexible knee coil were used. Both knees were examined. A three-dimensional DESS sequence was used and a three-dimensional reconstruction program was used to obtain axial reconstructions, from which a value for the width and thickness was calculated through the midpoint along the length of the patellar tendon from the apex of the patella to the tibial tubercle insertion (Fig 2). The midpoint of the patellar tendon at the donor site was then evaluated in terms of gap size (area corresponding to non–tendinous-like tissue signal) in the axial direction (Fig 3). All the measurements were made with a Siemens evaluation unit with the aid of computerized distance measurements using standardized settings. The intraobserver variation was ⫾ 1 mm, as assessed by re-evaluating 10 randomly selected examinations without any knowledge of the primary result.
Statistics Median (range) values are presented. The MannWhitney U two-tailed nonparametric test and the 2 test were used for comparisons between the groups. Spearman’s rank correlation test was used to test the correlations between the parameters. Wilcoxon matched-pairs signed-rank sum test was used to compare the patellar tendon at the donor site and the contralateral side; P ⬍ .05 was considered statistically significant. In calculations involving lost or disturbed anterior knee sensitivity, four patients in group B were excluded due to concomitant or previous incisions in the anterior knee region.
RESULTS The 2-year follow-up results are presented. The Tegner activity level, Lysholm score, and IKDC classification showed no significant difference between the patients in group A and group B. The same thing was found in terms of the subjective patellofemoral pain
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and the total side-to-side laxity difference as measured with the KT-1000. However, the one-leg hop test was significantly better in group B (Table 1). The area of lost or disturbed anterior knee sensitivity was 16 cm2 (0 to 200 cm2) in group A and 0 cm2 (0 to 285 cm2) in group B (P ⫽ .20). In group A, 7 of 35 patients had no loss of sensitivity at all compared with 19 of 33 patients in group B (P ⬍ .01) (In calculations involving lost or disturbed anterior knee sensitivity, four patients in group B and none in group A were excluded due to concomitant or previous incisions in the anterior knee region.) No difference was found between the groups in terms of the kneeling and knee-walking test (Table 2). The correlation between the loss of anterior knee sensitivity and the inability to kneel and knee-walk was significant in group A (P ⫽ .01, ⫽ .4) and nonsignificant in group B. MRI showed that the donor-site gap (area corresponding to non–tendinous-like tissue signal) was 5 mm (range, 0 to 9 mm) in group A and 2 mm (range, 0 to 5 mm) in group B (P ⬍ .0001). No significant difference was found in terms of the width and thickness of the residual patellar tendon between the FIGURE 3. A 2-year follow-up MRI evaluation in the axial dimension showing the donor-site gap (x-x). (Reprinted with permission.5 Copyright 1997 by Springer-Verlag.)
patients in group A and group B (Table 3). In both groups, the width and the thickness had significantly increased compared with the contralateral, nonharvested patellar tendon (Table 4). No correlation was found between the MRI findings and the knee-walking test in the two groups. DISCUSSION
FIGURE 2. A 2-year follow-up MRI evaluation in the axial dimension showing the width (x-x) and thickness (x-x) of the residual patellar tendon. (Reprinted with permission.5 Copyright 1997 by Springer-Verlag.)
The principal finding of this study was that, after the subcutaneous technique, there was less disturbance of anterior knee sensitivity and a smaller donor-site gap compared with the traditional technique. In both groups, the width and thickness of the patellar tendon had increased compared with the contralateral, nonharvested patellar tendon. Furthermore, in both groups, the MRI findings showed no correlation with the kneeling and knee-walking test. The strength of this prospective and controlled study was that the follow-up examination was performed by an independent observer and the radiographic evaluation was made by an independent radiologist without any knowledge of the primary treatment. The results at the follow-up in terms of the Lysholm
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TABLE 1. Results in Group A and Group B Using the Standard Evaluation Tools Group A (traditional harvest)
Group B (subcutaneous harvest)
Significance
6 (1-9) 90 (38-100) points 8/35 18/35 9/35 none 9/35 3 (⫺7 to 8.5) mm 88% (50%-113%)
7 (2-9) 88 (44-99) points 8/37 16/37 11/37 2/37 9/37 3 (⫺7 to 8.5) mm 96% (68%-132%)
NS NS NS NS NS NS NS NS P ⫽ .009
Tegner activity level Lysholm score IKDC normal (A) IKDC nearly normal (B) IKDC abnormal (C) IKDC severely abnormal (D) Subjective patellofemoral pain KT-1000 total side-to-side difference One-leg-hop test
NOTE. The value of the one-leg hop test was significantly (P ⫽ .009) superior in the patients who had had their patellar tendon autograft harvested using the traditional technique compared with the subcutaneous technique. A negative KT-1000 value indicates that the index side was less lax than the contralateral side.
score, Tegner activity level, IKDC evaluation system, and functional performance were all on a par with other studies.22 There was no difference between the two groups using the standard evaluation systems. However, none of the standard evaluation systems specifically assesses donor-site morbidity. This suggests that, from the subjective and functional point of view, the graft-harvesting technique has very little effect on the standard scores, as long as the disturbance of anterior knee sensitivity is not included in the evaluation system. The results of the one-leg hop test were superior in the subcutaneous group. One explanation could be that a more complete healing of the donor site enables the TABLE 2. The Loss of Anterior Knee Sensitivity and Knee-Walking Ability in Group A and Group B Group A (traditional harvest)
Group B (subcutaneous harvest)
0 (0-285) cm2 Disturbance of 16 (0-200) cm2 (median value) (median value, anterior knee 4 patients sensitivity excluded) No disturbance 7/35 patients 19/33 (4 patients of anterior excluded) knee sensitivity Knee-walking 5/35 patients 8/37 patients normal Knee-walking 10/35 patients 14/37 patients unpleasant Knee-walking 11/35 patients 3/37 patients difficult Knee-walking 9/35 patients 12/37 patients impossible
Significance P ⫽ .20
P ⬍ .01
NS NS NS NS
NOTE. Using the subcutaneous graft harvesting technique, significantly more patients had no disturbance of anterior knee sensitivity.
extensor mechanism to produce more force. Sparing the infrapatellar nerves might also contribute to less discomfort in the patellar tendon region when maximum force in extension is exerted. However, these theories have to be confirmed by additional studies. The present study shows that the subcutaneous technique is less detrimental to anterior knee sensitivity than the traditional technique, although approximately 40% of the patients also experienced a minor disturbance of sensitivity after the subcutaneous harvest. This was because of the fact that the infrapatellar nerve in many cases passes the patellar tendon region as several branches. In a dissection study, we registered as many as four branches in one patient.17 In group A, the inability to kneel and knee-walk correlated to the disturbance of anterior knee sensitivity (P ⫽ .01). This is in line with our previous findings in two studies comprising 90 and 604 patients, respectively.5,6 Berg and Mjo¨berg7 made the same observation in patients operated on using open knee ligament reconstructions. However, in group B, there was no correlation between the knee-walking test and the disturbance of anterior knee sensitivity. This was TABLE 3. MRI Findings in Group A and Group B Group A (traditional harvest)
Group B (subcutaneous harvest)
Donor-site gap 5 (0-9) mm 2 (0-5) mm Width of the donor-site patellar tendon 30 (23-39) mm 31 (24-38) mm Thickness of the donor-site patellar tendon 6 (4-9) mm 6 (4-9) mm
Significance P ⫽ .0001 NS
NS
NOTE. The donor-site gap was significantly smaller in group B using the subcutaneous graft harvesting technique.
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TABLE 4. Comparison Between the Patellar Tendon on the Normal Contralateral Side and the Donor Site Donor-Site Contralateral Patellar Tendon Patellar Tendon Significance Thickness group A 6 (4-9) mm 5 (3-7) mm Width group A 30 (23-39) mm 29 (22-36) mm Thickness group B 6 (4-9) mm 5 (3-8) mm Width group B 31 (24-38) mm 29 (20-35) mm
P ⫽ .0001 P ⫽ .02 P ⫽ .0001 P ⫽ .0002
NOTE. In both groups, the thickness and width on the donor-site patellar tendon were significantly increased compared with the normal contralateral side.
probably because of the fact that few patients displayed a major disturbance of anterior knee sensitivity in group B and, in this situation, other factors appear to influence donor-site morbidity. One of these factors could be loss of motion, as shown in our previous studies.5,6 However, in the present study, the patients were too few to test the correlation between the loss of motion and knee-walking ability. In the present study, the knee-walking test did not correlate with any of the MRI measurements. This implies that donor-site morbidity was not related to the tendon itself but instead, at least in group A, to dysesthesia after a peroperative injury to the infrapatellar nerve or one of its branches. The observation that sensory nerve injury at open meniscectomies, pes anserinus transplantation, and even blunt traumas may render pain and an inability to kneel has previously been made by several authors. 2,23-27 In two of our previous studies, MRI examinations have shown persistent non–tendinous-like tissue signal at the donor-site gap in all but one patient, 2 years after harvesting of the patellar tendon using the traditional technique.5,10 Weinstabl et al.16 have shown that the blood supply to the patellar tendon passes through the paratenon. The present study showed that the subcutaneous technique produced a smaller area of non–tendinous-like tissue signal at the donor-site of the patellar tendon at the 2-year assessment compared with the traditional technique. This might indicate that the healing process at the donor site is enhanced if the paratenon with its blood supply is left intact. However, MRI cannot be used to measure the quality of the repair tissue at the donor-site gap. Therefore, the present study only showed that tendinous-like signal in the central part of the patellar tendon was more common 2 years after graft harvest using the subcutaneous technique than using the traditional technique. Nixon et al.15 have shown that the patellar tendon had a normal appearance 2 years after harvesting the central third on both MRI and polarized light microscopy,
whereas, in a goat model, Proctor et al.28 showed that, even though the appearance on MRI was normal 21 months after harvest, transmission electron microscopy revealed abnormal tissue composition with an increased number of collagen fibrils of small diameter. It appears that histological evaluation would have added valuable information to the study. The finding that the thickness of the patellar tendon had increased 2 years after the harvest is supported by Coupens et al.11 using MRI and also by Wiley et al.13 using ultrasonography. This might imply that an ongoing healing process with inflammatory reactions is still present at the donor site 24 months after the harvest procedure. Since the knee-walking test in neither group A nor group B correlated with any of the MRI measurements, this might imply that donor-site morbidity is not solely related to the patellar tendon itself. CONCLUSION We were able to verify our hypothesis. At the 2-year assessment, the subcutaneous graft-harvesting technique produced significantly less disturbance in anterior knee sensitivity and a significantly smaller residual donor-site gap, compared with the traditional technique. REFERENCES 1. Breitfuss H, Fro¨hlich R, Povacz P, Resch H, Wicker A. The tendon defect after anterior cruciate ligament reconstruction using the midthird patellar tendon—A problem for the patellofemoral joint? Knee Surg Sports Traumatol Arthrosc 1996;3: 194-198. 2. Chambers GH. The prepatellar nerve. A cause of suboptimal results in knee arthrotomy. Clin Orthop 1972;82:157-159. 3. Sachs RA, Daniel DM, Stone ML, Garfein RF. Patellofemoral problems after anterior cruciate ligament reconstruction. Am J Sports Med 1989;17:760-765. 4. Shelbourne KD, Trumper RM. Preventing anterior knee pain after anterior cruciate ligament reconstruction. Am J Sports Med 1997;25:41-47. 5. Kartus J, Stener S, Lindahl S, Engstro¨m B, Eriksson BI, Karlsson J. Factors affecting donor-site morbidity after anterior cruciate ligament reconstruction using bone-patellar tendonbone autografts. Knee Surg Sports Traumatol Arthrosc 1997;5: 222-228. 6. Kartus J, Magnusson L, Stener S, Brandsson S, Eriksson BI, Karlsson J. Complications following arthroscopic anterior cruciate ligament reconstruction. A 2-5 year follow-up of 604 patients with special emphasis on anterior knee pain. Knee Surg Sports Traumatol Arthrosc 1998;7:2-8. 7. Berg P, Mjo¨berg B. A lateral incision reduces peripatellar dysesthesia after knee surgery. J Bone Joint Surg Br 1991;73: 374-376. 8. Cerullo G, Puddu G, Gianni E, Damiani A, Pigozzi F. Anterior cruciate ligament patellar tendon reconstruction: it is probably better to leave the tendon defect open! Knee Surg Sports Traumatol Arthrosc 1995;3:14-17.
COMPARISON OF PATELLAR TENDON HARVEST TECHNIQUES 9. Brandsson S, Faxe´n E, Eriksson BI, et al. Closing patellar tendon defect after anterior cruciate ligament reconstruction; absence of any benefit. Knee Surg Sports Traumatol Arthrosc 1997;6:82-87. 10. Kartus J, Stener S, Lindahl S, Eriksson BI, Karlsson J. Ipsi-or contralateral patellar tendon graft in anterior cruciate ligament revision surgery. A comparison of two methods. Am J Sports Med 1997;26:499-504. 11. Coupens SD, Yates CK, Sheldon C, Ward C. Magnetic resonance imaging evaluation of the patellar tendon after use of its central one-third for anterior cruciate ligament reconstruction. Am J Sports Med 1992;20:332-335. 12. Berg EE. Intrinsic healing of a patellar tendor donor site defect after anterior cruciate ligament reconstraction. Clin Orthop 1992;278:160-163. 13. Wiley JP, Bray RC, Wiseman DA, Elliott PD, Ladly KO, Vale LA. Serial ultrasonographic imaging evaluation of the patellar tendon after harvesting its central one third for anterior cruciate ligament reconstruction. J Ultrasound Med 1997;16:251-255. 14. Rosenberg TD, Franklin JL, Baldwin GN, Nelson KA. Extensor mechanism function after patellar tendon graft harvest for anterior cruciate ligament reconstruction. Am J Sports Med 1992;20:519-526. 15. Nixon RG, SeGall GK, Sax SL, Cain TE, Tullos HS. Reconstitution of the patellar tendon donor site after graft harvest. Clin Orthop 1995;317:162-171. 16. Weinstabl R, Wagner M, Schabus R, Firbas W. Anatomical bases of patellar tendon grafts used in anterior cruciate ligament reconstruction. Surg Radiol Anat 1986;8:163-167. 17. Kartus J, Ejerhed L, Eriksson BI, Karlsson J. The localization of the infrapatellar nerves in the anterior knee region with special emphasis on patellar tendon harvest. A dissection study on cadaver and amputated specimens Arthroscopy 1998; 15:577-586.
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18. Tegner Y, Lysholm J. Rating systems in the evaluation of knee ligament injuries. Clin Orthop 1985;198:43-49. 19. Hefti F, Mu¨ller W, Jakob RP, Sta¨ubli HU. Evaluation of knee ligament injuries with the IKDC form. Knee Surg Sports Traumatol Arthrosc 1993;1:226-234. 20. Shelbourne KD, Nitz P. Accelerated rehabilitation after anterior cruciate ligament reconstruction. Am J Sports Med 1990;18:292299. 21. Kartus J, Stener S, Ko¨hler K, Sernert N, Eriksson BI, Karlsson J. Is bracing after anterior cruciate ligament reconstruction necessary? A 2-year follow-up of 78 consecutive patients rehabilitated with or without a brace. Knee Surg Sports Traumatol Arthrosc 1997;5:157-161. 22. Bach BR, Jones GT, Sweet FA, Hager CA. Arthroscopyassisted anterior cruciate ligament reconstrucion using patellar tendon substitution. Two-to four-year follow-up results. Am J Sports Med 1994;22:758-767. 23. Johnson RJ, Kettelkamp DB, Clark W, Leaverton P. Factors affecting late results after meniscectomy. J Bone Joint Surg Am 1974;56:719-729. 24. Slocum DB, Larson RL, Oregon E. Pes anserinus transplantation. J Bone Joint Surg Am 1968;50:226-242. 25. Tapper EM, Hoover NW. Late results after meniscectomy. J Bone Joint Surg Am 1969;51:517-526. 26. Detenbeck LC. Infrapatellar traumatic neuroma resulting from dashboard injury. J Bone Joint Surg Am 1972;54:170-172. 27. Gordon GC. Traumatic prepatellar neuralgia. J Bone Joint Surg Br 1952;34:41-44. 28. Proctor CS, Jackson DW, Simon TM. Characterization of the repair tissue after removal of the central one-third of the patellar ligament. J Bone Joint Surg Am 1997;79:9971006.
Summary: The aim of this study was to compare the 2-year results after anterior cruciate ligament reconstruction using patellar tendon autografts harvested through a paratenon-splitting, traditional technique (group A) with the results of a subcutaneous technique aiming at protecting the infrapatellar nerves and the paratenon (group B). Special emphasis was placed on evaluating the donor site. Magnetic resonance imaging (MRI) of the patellar tendon was performed to evaluate the reconstitution after harvesting its central third. Examinations of knee-walking ability and assessments of anterior knee sensitivity were made in order to evaluate donor-site discomfort and the function of infrapatellar nerves. Seventy-two consecutive patients were included in the study; group A comprised 35 patients and group B, 37 patients. At the 2-year follow-up, the Tegner activity level, the Lysholm score, and the IKDC evaluation system showed no significant differences between groups A and B. The median loss of normal anterior knee sensitivity was 16 cm2 (range, 0 to 200 cm2) in group A and 0 cm2 (range, 0 to 285 cm2) in group B (P ⫽ .20). In group A 20% of the patients and in group B 58% had normal sensitivity (P ⬍ .01). MRI showed that the donor-site gap (area corresponding to non–tendinous-like tissue signal) was 5 mm (range, 0 to 9 mm) in group A and 2 mm (range, 0 to 5 mm) in group B (P ⬍ .0001). At 2-year follow-up, the subcutaneous graft-harvesting technique resulted in less disturbance of anterior knee sensitivity and a smaller donor-site gap than the traditional technique. Key Words: Anterior cruciate—Patellar ligament—Magnetic resonance imaging— Donor-site—Harvesting technique.
D
onor-site morbidity is reported in 40% to 60% of patients after anterior cruciate ligament reconstruction using patellar tendon autograft.1 Most evaluations
From the Department of Orthopaedics (J.K., S.S.) and Diagnostic Radiology (S.L.), Norra A¨lvsborg Hospital; and the Department of Orthopaedics, Sahlgrens University Hospital (B.I.E., J.K.), Go¨teborg, Sweden. Supported by grants from the Research and Development Department of Northern A¨lvsborg and the Swedish National Centre for Research in Sports. Address correspondence and reprint requests to Ju¨ri Kartus, M.D., Department of Orthopaedics, Norra A¨lvsborgs Hospital, SE-461 85 Trollha¨ttan, Sweden. E-mail: juri.kartus@trollhattan. mail.telia.com r 1999 by the Arthroscopy Association of North America 0749-8063/99/1506-1961$3.00/0
of donor-site morbidity do not assess the patellar tendon itself, but rather the secondary symptoms that occur. Symptoms such as local tenderness, dysesthesia, anterior knee pain, stiffness, and inability to kneel and knee-walk have all been described after central patellar tendon harvest or after incisions in the anterior knee region.2-7 It is now understood that there is no advantage in closing the donor-site after harvesting its central third.8,9 Probably as a result of an inflammatory reaction, the remaining two thirds of the patellar tendon undergo an increase in cross-sectional area that appears to be persistent, at least up to 24 months after the harvest, as has been shown by several investiga-
Arthroscopy: The Journal of Arthroscopic and Related Surgery, Vol 15, No 6 (September), 1999: pp 587–593
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tors.5,10-13 Whether the patellar tendon is able to regenerate after harvesting its central third is controversial. Rosenberg et al.14 stated that the donor site displays significant scar formation and persistent defects 12 to 24 months after the harvest, when examined using both computed tomography (CT) and magnetic resonance imaging (MRI). However, both Nixon et al.15 and Berg12 claim that the central tendon defect heals as assessed by MRI and histological examination. Weinstabl et al.16 have shown that the blood supply to the patellar tendon passes through the paratenon. In a dissection study of cadaver and amputated specimens, we have shown that it is possible to harvest the central third of the patellar tendon through two 25-mm vertical incisions, leaving the infrapatellar nerves and the paratenon partially intact in the majority of specimens.17 Theoretically, the healing of the donor-site gap might occur more rapidly if the paratenon were left intact and the disturbance of anterior knee sensitivity might be less if the integrity of the infrapatellar nerves were respected. The hypothesis of this study was that patellar tendon harvest using the subcutaneous technique produces less disturbance of anterior knee sensitivity and a more complete healing of the donor-site gap than the traditional technique. PATIENTS AND METHODS Seventy-two patients who underwent anterior cruciate ligament reconstruction in a consecutive prospective series and at the 2-year follow-up agreed to undergo an MRI evaluation were included in the study. Group A comprised 35 consecutive patients (12 female and 23 male) who had previously had their patellar tendon harvested through a single vertical paratenon-splitting 70-mm skin incision. Group B comprised 37 consecutive patients (12 female and 25 male) who had had their patellar tendon harvested through two vertical 25-mm skin incisions.17 The average age of the patients at the time of the index operation was 26 years (range, 14 to 44 years) in group A and 27 years (range, 14 to 50 years) in group B (not significant). The time between the injury and the index operation was 15 months (range, 1 to 168 months) in group A and 12 months (range, 2 to 192 months) in group B (not significant). The preinjury Tegner level of activity18 was 9 (range, 4-9) in group A and 9 (range, 5-9) in group B (not significant). An independent observer performed all the fol-
low-up examinations after 24 months (range, 22 to 29 months) in group A and 25 months (range, 23 to 29 months) in group B. The follow-up was based on the Lysholm score18, the Tegner activity level,18 and the IKDC evaluation system.19 The functional performance was evaluated using the one-leg hoptest.19 Special attention was paid to the anterior knee region. The skin was palpated by touch of the examiners fingers and the area of lost or disturbed anterior knee sensitivity was measured in square centimeters. The kneeling and knee-walking ability was tested and subjectively classified by the patient as normal, unpleasant, difficult, or impossible.5,6 The patients were classified as having subjective anterior knee pain if the pain was related to activity, stair walking, and sitting with their knees flexed at 90°. Surgical Technique All the patients had their ligament injury reconstructed by one experienced arthroscopic surgeon using patellar tendon autograft. A standard oneincision technique was used with the femoral interference screw inserted through the anterior portal and the tibial interference screw from the outside. In group A, the patellar tendon was harvested through a 70-mm skin incision, the paratenon was split along its entire length, and no effort was made to isolate and spare the infrapatellar nerves. At the end of the surgical procedure, the tendon defect was left open and the paratenon was closed as meticulously as possible. In group B, the patellar tendon was harvested through two 25-mm vertical skin incisions, tunneling the graft subcutaneously and under the paratenon with the aim of leaving the major part of the paratenon closed and the infrapatellar nerves intact, as described in the report of a previous dissection study also published in this issue (Fig 1).17 At the end of the procedure, the two small incisions in the paratenon were closed as meticulously as possible. Rehabilitation The patients in both groups were rehabilitated according to an identical protocol with immediate full range of motion, full weight-bearing, and early closedchain exercises.20 A rehabilitation brace was not used with the exception of nine patients in group A.21 Running was permitted at 3 months and contact sports at 6 months. MRI Examination One independent radiologist without any knowledge of the primary treatment made all the radio-
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FIGURE 1. In group B, the patellar tendon was harvested through two 25-mm vertical skin incisions, tunneling the graft subcutaneously and under the paratenon, with the aim of leaving the major part of the paratenon undamaged and the infrapatellar nerves intact.
graphic assessments. The patients in group A and group B were examined 27 months (range, 22 to 38 months) and 27 months (range, 24 to 29 months) months, respectively, after the index operation. A Siemens Magnetom 1.0 Tesla (Siemens, Erlangen, Germany) and a flexible knee coil were used. Both knees were examined. A three-dimensional DESS sequence was used and a three-dimensional reconstruction program was used to obtain axial reconstructions, from which a value for the width and thickness was calculated through the midpoint along the length of the patellar tendon from the apex of the patella to the tibial tubercle insertion (Fig 2). The midpoint of the patellar tendon at the donor site was then evaluated in terms of gap size (area corresponding to non–tendinous-like tissue signal) in the axial direction (Fig 3). All the measurements were made with a Siemens evaluation unit with the aid of computerized distance measurements using standardized settings. The intraobserver variation was ⫾ 1 mm, as assessed by re-evaluating 10 randomly selected examinations without any knowledge of the primary result.
Statistics Median (range) values are presented. The MannWhitney U two-tailed nonparametric test and the 2 test were used for comparisons between the groups. Spearman’s rank correlation test was used to test the correlations between the parameters. Wilcoxon matched-pairs signed-rank sum test was used to compare the patellar tendon at the donor site and the contralateral side; P ⬍ .05 was considered statistically significant. In calculations involving lost or disturbed anterior knee sensitivity, four patients in group B were excluded due to concomitant or previous incisions in the anterior knee region.
RESULTS The 2-year follow-up results are presented. The Tegner activity level, Lysholm score, and IKDC classification showed no significant difference between the patients in group A and group B. The same thing was found in terms of the subjective patellofemoral pain
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and the total side-to-side laxity difference as measured with the KT-1000. However, the one-leg hop test was significantly better in group B (Table 1). The area of lost or disturbed anterior knee sensitivity was 16 cm2 (0 to 200 cm2) in group A and 0 cm2 (0 to 285 cm2) in group B (P ⫽ .20). In group A, 7 of 35 patients had no loss of sensitivity at all compared with 19 of 33 patients in group B (P ⬍ .01) (In calculations involving lost or disturbed anterior knee sensitivity, four patients in group B and none in group A were excluded due to concomitant or previous incisions in the anterior knee region.) No difference was found between the groups in terms of the kneeling and knee-walking test (Table 2). The correlation between the loss of anterior knee sensitivity and the inability to kneel and knee-walk was significant in group A (P ⫽ .01, ⫽ .4) and nonsignificant in group B. MRI showed that the donor-site gap (area corresponding to non–tendinous-like tissue signal) was 5 mm (range, 0 to 9 mm) in group A and 2 mm (range, 0 to 5 mm) in group B (P ⬍ .0001). No significant difference was found in terms of the width and thickness of the residual patellar tendon between the FIGURE 3. A 2-year follow-up MRI evaluation in the axial dimension showing the donor-site gap (x-x). (Reprinted with permission.5 Copyright 1997 by Springer-Verlag.)
patients in group A and group B (Table 3). In both groups, the width and the thickness had significantly increased compared with the contralateral, nonharvested patellar tendon (Table 4). No correlation was found between the MRI findings and the knee-walking test in the two groups. DISCUSSION
FIGURE 2. A 2-year follow-up MRI evaluation in the axial dimension showing the width (x-x) and thickness (x-x) of the residual patellar tendon. (Reprinted with permission.5 Copyright 1997 by Springer-Verlag.)
The principal finding of this study was that, after the subcutaneous technique, there was less disturbance of anterior knee sensitivity and a smaller donor-site gap compared with the traditional technique. In both groups, the width and thickness of the patellar tendon had increased compared with the contralateral, nonharvested patellar tendon. Furthermore, in both groups, the MRI findings showed no correlation with the kneeling and knee-walking test. The strength of this prospective and controlled study was that the follow-up examination was performed by an independent observer and the radiographic evaluation was made by an independent radiologist without any knowledge of the primary treatment. The results at the follow-up in terms of the Lysholm
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TABLE 1. Results in Group A and Group B Using the Standard Evaluation Tools Group A (traditional harvest)
Group B (subcutaneous harvest)
Significance
6 (1-9) 90 (38-100) points 8/35 18/35 9/35 none 9/35 3 (⫺7 to 8.5) mm 88% (50%-113%)
7 (2-9) 88 (44-99) points 8/37 16/37 11/37 2/37 9/37 3 (⫺7 to 8.5) mm 96% (68%-132%)
NS NS NS NS NS NS NS NS P ⫽ .009
Tegner activity level Lysholm score IKDC normal (A) IKDC nearly normal (B) IKDC abnormal (C) IKDC severely abnormal (D) Subjective patellofemoral pain KT-1000 total side-to-side difference One-leg-hop test
NOTE. The value of the one-leg hop test was significantly (P ⫽ .009) superior in the patients who had had their patellar tendon autograft harvested using the traditional technique compared with the subcutaneous technique. A negative KT-1000 value indicates that the index side was less lax than the contralateral side.
score, Tegner activity level, IKDC evaluation system, and functional performance were all on a par with other studies.22 There was no difference between the two groups using the standard evaluation systems. However, none of the standard evaluation systems specifically assesses donor-site morbidity. This suggests that, from the subjective and functional point of view, the graft-harvesting technique has very little effect on the standard scores, as long as the disturbance of anterior knee sensitivity is not included in the evaluation system. The results of the one-leg hop test were superior in the subcutaneous group. One explanation could be that a more complete healing of the donor site enables the TABLE 2. The Loss of Anterior Knee Sensitivity and Knee-Walking Ability in Group A and Group B Group A (traditional harvest)
Group B (subcutaneous harvest)
0 (0-285) cm2 Disturbance of 16 (0-200) cm2 (median value) (median value, anterior knee 4 patients sensitivity excluded) No disturbance 7/35 patients 19/33 (4 patients of anterior excluded) knee sensitivity Knee-walking 5/35 patients 8/37 patients normal Knee-walking 10/35 patients 14/37 patients unpleasant Knee-walking 11/35 patients 3/37 patients difficult Knee-walking 9/35 patients 12/37 patients impossible
Significance P ⫽ .20
P ⬍ .01
NS NS NS NS
NOTE. Using the subcutaneous graft harvesting technique, significantly more patients had no disturbance of anterior knee sensitivity.
extensor mechanism to produce more force. Sparing the infrapatellar nerves might also contribute to less discomfort in the patellar tendon region when maximum force in extension is exerted. However, these theories have to be confirmed by additional studies. The present study shows that the subcutaneous technique is less detrimental to anterior knee sensitivity than the traditional technique, although approximately 40% of the patients also experienced a minor disturbance of sensitivity after the subcutaneous harvest. This was because of the fact that the infrapatellar nerve in many cases passes the patellar tendon region as several branches. In a dissection study, we registered as many as four branches in one patient.17 In group A, the inability to kneel and knee-walk correlated to the disturbance of anterior knee sensitivity (P ⫽ .01). This is in line with our previous findings in two studies comprising 90 and 604 patients, respectively.5,6 Berg and Mjo¨berg7 made the same observation in patients operated on using open knee ligament reconstructions. However, in group B, there was no correlation between the knee-walking test and the disturbance of anterior knee sensitivity. This was TABLE 3. MRI Findings in Group A and Group B Group A (traditional harvest)
Group B (subcutaneous harvest)
Donor-site gap 5 (0-9) mm 2 (0-5) mm Width of the donor-site patellar tendon 30 (23-39) mm 31 (24-38) mm Thickness of the donor-site patellar tendon 6 (4-9) mm 6 (4-9) mm
Significance P ⫽ .0001 NS
NS
NOTE. The donor-site gap was significantly smaller in group B using the subcutaneous graft harvesting technique.
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TABLE 4. Comparison Between the Patellar Tendon on the Normal Contralateral Side and the Donor Site Donor-Site Contralateral Patellar Tendon Patellar Tendon Significance Thickness group A 6 (4-9) mm 5 (3-7) mm Width group A 30 (23-39) mm 29 (22-36) mm Thickness group B 6 (4-9) mm 5 (3-8) mm Width group B 31 (24-38) mm 29 (20-35) mm
P ⫽ .0001 P ⫽ .02 P ⫽ .0001 P ⫽ .0002
NOTE. In both groups, the thickness and width on the donor-site patellar tendon were significantly increased compared with the normal contralateral side.
probably because of the fact that few patients displayed a major disturbance of anterior knee sensitivity in group B and, in this situation, other factors appear to influence donor-site morbidity. One of these factors could be loss of motion, as shown in our previous studies.5,6 However, in the present study, the patients were too few to test the correlation between the loss of motion and knee-walking ability. In the present study, the knee-walking test did not correlate with any of the MRI measurements. This implies that donor-site morbidity was not related to the tendon itself but instead, at least in group A, to dysesthesia after a peroperative injury to the infrapatellar nerve or one of its branches. The observation that sensory nerve injury at open meniscectomies, pes anserinus transplantation, and even blunt traumas may render pain and an inability to kneel has previously been made by several authors. 2,23-27 In two of our previous studies, MRI examinations have shown persistent non–tendinous-like tissue signal at the donor-site gap in all but one patient, 2 years after harvesting of the patellar tendon using the traditional technique.5,10 Weinstabl et al.16 have shown that the blood supply to the patellar tendon passes through the paratenon. The present study showed that the subcutaneous technique produced a smaller area of non–tendinous-like tissue signal at the donor-site of the patellar tendon at the 2-year assessment compared with the traditional technique. This might indicate that the healing process at the donor site is enhanced if the paratenon with its blood supply is left intact. However, MRI cannot be used to measure the quality of the repair tissue at the donor-site gap. Therefore, the present study only showed that tendinous-like signal in the central part of the patellar tendon was more common 2 years after graft harvest using the subcutaneous technique than using the traditional technique. Nixon et al.15 have shown that the patellar tendon had a normal appearance 2 years after harvesting the central third on both MRI and polarized light microscopy,
whereas, in a goat model, Proctor et al.28 showed that, even though the appearance on MRI was normal 21 months after harvest, transmission electron microscopy revealed abnormal tissue composition with an increased number of collagen fibrils of small diameter. It appears that histological evaluation would have added valuable information to the study. The finding that the thickness of the patellar tendon had increased 2 years after the harvest is supported by Coupens et al.11 using MRI and also by Wiley et al.13 using ultrasonography. This might imply that an ongoing healing process with inflammatory reactions is still present at the donor site 24 months after the harvest procedure. Since the knee-walking test in neither group A nor group B correlated with any of the MRI measurements, this might imply that donor-site morbidity is not solely related to the patellar tendon itself. CONCLUSION We were able to verify our hypothesis. At the 2-year assessment, the subcutaneous graft-harvesting technique produced significantly less disturbance in anterior knee sensitivity and a significantly smaller residual donor-site gap, compared with the traditional technique. REFERENCES 1. Breitfuss H, Fro¨hlich R, Povacz P, Resch H, Wicker A. The tendon defect after anterior cruciate ligament reconstruction using the midthird patellar tendon—A problem for the patellofemoral joint? Knee Surg Sports Traumatol Arthrosc 1996;3: 194-198. 2. Chambers GH. The prepatellar nerve. A cause of suboptimal results in knee arthrotomy. Clin Orthop 1972;82:157-159. 3. Sachs RA, Daniel DM, Stone ML, Garfein RF. Patellofemoral problems after anterior cruciate ligament reconstruction. Am J Sports Med 1989;17:760-765. 4. Shelbourne KD, Trumper RM. Preventing anterior knee pain after anterior cruciate ligament reconstruction. Am J Sports Med 1997;25:41-47. 5. Kartus J, Stener S, Lindahl S, Engstro¨m B, Eriksson BI, Karlsson J. Factors affecting donor-site morbidity after anterior cruciate ligament reconstruction using bone-patellar tendonbone autografts. Knee Surg Sports Traumatol Arthrosc 1997;5: 222-228. 6. Kartus J, Magnusson L, Stener S, Brandsson S, Eriksson BI, Karlsson J. Complications following arthroscopic anterior cruciate ligament reconstruction. A 2-5 year follow-up of 604 patients with special emphasis on anterior knee pain. Knee Surg Sports Traumatol Arthrosc 1998;7:2-8. 7. Berg P, Mjo¨berg B. A lateral incision reduces peripatellar dysesthesia after knee surgery. J Bone Joint Surg Br 1991;73: 374-376. 8. Cerullo G, Puddu G, Gianni E, Damiani A, Pigozzi F. Anterior cruciate ligament patellar tendon reconstruction: it is probably better to leave the tendon defect open! Knee Surg Sports Traumatol Arthrosc 1995;3:14-17.
COMPARISON OF PATELLAR TENDON HARVEST TECHNIQUES 9. Brandsson S, Faxe´n E, Eriksson BI, et al. Closing patellar tendon defect after anterior cruciate ligament reconstruction; absence of any benefit. Knee Surg Sports Traumatol Arthrosc 1997;6:82-87. 10. Kartus J, Stener S, Lindahl S, Eriksson BI, Karlsson J. Ipsi-or contralateral patellar tendon graft in anterior cruciate ligament revision surgery. A comparison of two methods. Am J Sports Med 1997;26:499-504. 11. Coupens SD, Yates CK, Sheldon C, Ward C. Magnetic resonance imaging evaluation of the patellar tendon after use of its central one-third for anterior cruciate ligament reconstruction. Am J Sports Med 1992;20:332-335. 12. Berg EE. Intrinsic healing of a patellar tendor donor site defect after anterior cruciate ligament reconstraction. Clin Orthop 1992;278:160-163. 13. Wiley JP, Bray RC, Wiseman DA, Elliott PD, Ladly KO, Vale LA. Serial ultrasonographic imaging evaluation of the patellar tendon after harvesting its central one third for anterior cruciate ligament reconstruction. J Ultrasound Med 1997;16:251-255. 14. Rosenberg TD, Franklin JL, Baldwin GN, Nelson KA. Extensor mechanism function after patellar tendon graft harvest for anterior cruciate ligament reconstruction. Am J Sports Med 1992;20:519-526. 15. Nixon RG, SeGall GK, Sax SL, Cain TE, Tullos HS. Reconstitution of the patellar tendon donor site after graft harvest. Clin Orthop 1995;317:162-171. 16. Weinstabl R, Wagner M, Schabus R, Firbas W. Anatomical bases of patellar tendon grafts used in anterior cruciate ligament reconstruction. Surg Radiol Anat 1986;8:163-167. 17. Kartus J, Ejerhed L, Eriksson BI, Karlsson J. The localization of the infrapatellar nerves in the anterior knee region with special emphasis on patellar tendon harvest. A dissection study on cadaver and amputated specimens Arthroscopy 1998; 15:577-586.
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18. Tegner Y, Lysholm J. Rating systems in the evaluation of knee ligament injuries. Clin Orthop 1985;198:43-49. 19. Hefti F, Mu¨ller W, Jakob RP, Sta¨ubli HU. Evaluation of knee ligament injuries with the IKDC form. Knee Surg Sports Traumatol Arthrosc 1993;1:226-234. 20. Shelbourne KD, Nitz P. Accelerated rehabilitation after anterior cruciate ligament reconstruction. Am J Sports Med 1990;18:292299. 21. Kartus J, Stener S, Ko¨hler K, Sernert N, Eriksson BI, Karlsson J. Is bracing after anterior cruciate ligament reconstruction necessary? A 2-year follow-up of 78 consecutive patients rehabilitated with or without a brace. Knee Surg Sports Traumatol Arthrosc 1997;5:157-161. 22. Bach BR, Jones GT, Sweet FA, Hager CA. Arthroscopyassisted anterior cruciate ligament reconstrucion using patellar tendon substitution. Two-to four-year follow-up results. Am J Sports Med 1994;22:758-767. 23. Johnson RJ, Kettelkamp DB, Clark W, Leaverton P. Factors affecting late results after meniscectomy. J Bone Joint Surg Am 1974;56:719-729. 24. Slocum DB, Larson RL, Oregon E. Pes anserinus transplantation. J Bone Joint Surg Am 1968;50:226-242. 25. Tapper EM, Hoover NW. Late results after meniscectomy. J Bone Joint Surg Am 1969;51:517-526. 26. Detenbeck LC. Infrapatellar traumatic neuroma resulting from dashboard injury. J Bone Joint Surg Am 1972;54:170-172. 27. Gordon GC. Traumatic prepatellar neuralgia. J Bone Joint Surg Br 1952;34:41-44. 28. Proctor CS, Jackson DW, Simon TM. Characterization of the repair tissue after removal of the central one-third of the patellar ligament. J Bone Joint Surg Am 1997;79:9971006.