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Patellofemoral Replacement: The Third Compartment
Patellofemoral Replacement: The Third Compartment Aaron A. Hofmann, MD,* C. Dana Clark, MD,* Corey Ponder, MD,† and Michael Hoffman, MD‡ Isolated patellofemoral arthritis is not an uncommon problem, with no clear consensus on treatment. Nonoperative and many forms of operative treatment have failed to demonstrate long-term effectiveness in the setting of advanced arthritis. Total knee arthroplasty (TKA) has produced excellent results, but many surgeons are hesitant to perform TKA in younger patients with isolated patellofemoral arthritis. In properly selected patients, patellofemoral arthroplasty (PFA) is an effective procedure with good long-term results. Contemporary PFA prostheses have eliminated many of the patellar maltracking problems associated with older designs, and short-term results, as described here, are encouraging. Long-term outcome and prospective trials comparing TKA to PFA are needed. Semin Arthro 20:29-34 © 2009 Published by Elsevier Inc. KEYWORDS patellofemoral arthritis, patellofemoral arthroplasty
I
solated patellofemoral arthritis is a common problem among orthopedic patients, affecting approximately 11% of men and 24% of women over the age of 55 years.1,2 Despite the high prevalence of this condition, no clear consensus exists within the orthopedic community as to how best to treat this condition. Nonoperative forms of treatment tend to be ineffective or only provide temporary relief, and many forms of operative treatment have disappointing outcomes. Total knee arthroplasty (TKA) has been shown to provide effective and lasting pain relief for isolated patellofemoral arthritis,3-7 however many patients and physicians have reservations in performing such an invasive procedure for a unicompartmental condition. Patellofemoral arthroplasty (PFA) has been performed for over 50 years for isolated patellofemoral arthritis and initially had poor results with high complication rates.8-15 In recent times, newer prosthetic designs have been shown to produce reliably good results with high rates of survivorship in the short term.16-20 The following article reviews isolated patellofemoral arthritis, with special emphasis on how PFA pertains to its treatment. Finally, the shortterm results of the anatomically designed Natural Knee II Patello-femoral Joint System will be presented.
*Department of Orthopaedics, University of Utah, Salt Lake City, UT, USA. †Oklahoma Sports and Orthopedics Institute, Edmond, OK, USA. ‡1705 Warren Avenue, Williamsport, PA, USA. Address reprint requests to A.A. Hofmann, MD, University of Utah, Department of Orthopaedics, 590 Wakara Way, Salt Lake City, UT 84108. E-mail: [email protected]
1045-4527/09/$-see front matter © 2009 Published by Elsevier Inc. doi:10.1053/j.sart.2008.11.014
Epidemiology and Etiology Isolated patellofemoral arthritis is a common problem. Epidemiologic studies have shown that 11% of men and 24% of women older than 55 years of age with symptomatic arthritis have disease isolated to the patellofemoral joint.2 Similar findings have been published on orthopedic outpatients over the age of 40, wherein 9.2% of patients presenting with knee pain had radiographic signs of isolated patellofemoral arthritis.1 Much like a varus knee, patellofemoral arthritis commonly stems from problems with malalignment, but it can also be associated with other conditions including dysplasia, instability, trauma, inflammatory arthritis, and osteoarthritis.21 Malalignment can stem from a tight lateral retinaculum, an abnormal Q angle, or abnormal femoral torsion. All of these manifest in excessive pressure on the lateral aspect of the patella and pose an increased risk for the development of arthritis over time.22 Patellofemoral dysplasia also contributes to malalignment and is strongly associated with the development of patellofemoral arthritis.4,5 Dejour and Allain23 found it to be the most common predisposing factor, with 78% of patients having radiographic signs of trochlear dysplasia. Higher grades of arthritis have also been correlated to higher grades of dysplasia.22 Patellar dislocation and trauma are also common causes. In fact nearly one-third of patellofemoral arthroplasties in one series were performed in patients with previous trauma.21,24 Osteoarthritis and inflammatory conditions can also manifest by first involving the patellofemoral joint, and careful attention to the tibiofemoral compartments should be paid before proceeding with isolated patellofemoral procedures. 29
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Clinical Presentation and Diagnosis When arthritic changes of the patellofemoral joint are present on radiographs, it is easy to assign this as the cause of a patient’s knee pain. However, it must be kept in mind that there are several causes of anterior knee pain and arthritis may not be the cause. These conditions include referred pain from the hip or spine, overuse syndromes (tendonitis), synovitis, bursitis, and neoplastic processes.25 With a careful clinical evaluation, these causes can be ruled out. Patients with isolated patellofemoral arthritis commonly complain of knee pain that is anterior in nature. Pain is typically aggravated by activities that increase the load across the patellofemoral joint, such as rising from a chair, climbing and descending stairs, or squatting. It is typically relieved by activities that decrease the load, such as walking on level ground and sitting with the knee extended. Often times the knee pain may extend back to adolescence and a history of prior patellar dislocations or subluxations may be present. Pain that is more global or located in the medial and lateral compartments of the knee is more indicative of systemic knee arthritis. Physical examination findings will typically reveal crepitus and tenderness about the patellofemoral joint and tenderness under the lateral facet. Many patients will have patellar tracking abnormalities evident during active range of motion testing and often the patella will point inward with standing.25 Palpation of the quadriceps and patellar tendons as well as the prepatellar bursa should be performed, as well as a hip examination, to rule out referred pain. Tenderness present at the medial or lateral joint line should alert the examiner of the possibility of more diffuse arthritis. Plain radiographs are typically sufficient for the work-up of patellofemoral arthritis. Weight-bearing anteroposterior and midflexion views should be obtained to rule out tibiofemoral disease. The diagnosis is most easily made on the lateral and Merchant26 views, where joint space narrowing and osteophyte formation will be evident, particularly on the lateral side. Trochlear dysplasia and abnormal patellar tilt should be noted, as these can provide evidence that the arthritis is not from a more systemic cause that has simply involved the patellofemoral joint first.
Treatment Options Nonoperative Treatment Most authors recommend a trial of nonoperative treatment for patients with patellofemoral arthritis, especially in mild to moderate cases. Treatment options include activity modification, quadriceps strengthening, bracing, nonsteroidal antiinflammatories, glucosamine– chondroitin, and viscosupplementation.25 Unfortunately, none of these have been proven to be markedly effective, especially in the setting of advanced arthritis.25-28
Operative Treatment Excluding Arthroplasty Surgical intervention is often indicated for those patients who fail nonoperative treatment and have pain that is disabling.
Table 1 Possible Surgical Solutions for Isolated Patellofemoral Arthritis Arthroscopic debridement Microfracture articular restoration Lateral release Soft tissue realignment Osteotomies of the tibial tubercle
Mosaicplasty/ACI Lateral patella partial facetectomy Patellectomy Patellofemoral arthroplasty Total knee arthroplasty
There are numerous proposed surgical treatment options for patellofemoral arthritis (Table 1). Lateral release, which is commonly employed for patellar maltracking, has also been used for the treatment of isolated patellofemoral arthritis, and results have been less than encouraging. Aderinto and Cobb29 studied 54 knees treated with lateral release, 26 of which had isolated patellofemoral arthritis. They found that only 50% of the patients were satisfied with the procedure and 4 were converted to TKA within 18 months. Osteotomies of the tibial tubercle have been studied for treatment of patellofemoral arthritis as well, and unfortunately they have not provided good results either. The Maquet operation, a straight anterior transfer of the tuberosity, has been used by several authors to treat patellofemoral arthritis.30-32 Heatley and coworkers31 reported on 14 knees with patellofemoral arthritis and, at 6-year follow-up, 6 knees were rated good to excellent, 3 fair, and the remaining 5 poor. The procedure also has number of complications, including skin necrosis, osteotomy fragment fracture, patellar tendonitis, as well as a painful prominence.30,31 The Fulkerson osteotomy, anteromedialization of the tibial tubercle, has also been studied. This operation is more appealing in that it unloads the lateral aspect of the patella; however, it is more technically demanding to perform.33 Results have been similar to the Maquet osteotomy, but improved results have been reported for arthritis isolated to the lateral facet of the patella, rather than complete involvement of the articulation.34 Results of autologous chondrocyte implantation used to treat patellofemoral arthritis were initially quite poor;35 however, more recent investigations have found somewhat improved results, with most patients reporting good pain relief and improved function.36 Fairly high graft failure rates are still reported, nearly 20%, and most of these patients were young without systemic involvement of the patellofemoral joint. The high cost of this procedure is of significant concern. Patellectomy has been used to treat patellofemoral disease for nearly 100 years. Analyzing the data for patellectomy is difficult, as much of it is conflicting and patient populations are quite heterogeneous. The most recent studies show that it is likely an effective pain-relieving procedure,37,38 but most surgeons tend to avoid it because of its irreversible nature and the marked reduction in extensor mechanism strength that occurs. If performed, tubularization of the extensor mechanism is recommended.39
Patellofemoral replacment
31
Total Knee Arthroplasty
Table 3 Contraindications to Patellofemoral Arthroplasty
Total knee arthroplasty has been well studied in the treatment of isolated patellofemoral arthritis, and all studies report high rates of survivorship and large percentages of good to excellent results in short- to midterm follow-up. Laskin and van Steijn3 studied 53 knees at an average follow-up of 7.4 years. They reported that 81% of patients had good to excellent results, with mean Knee Society scores of 47 and 96 points for pain and function, respectively. The overall survivorship was 98%, with 1 knee requiring revision and 1 patient undergoing above-knee amputation. Mont and coworkers4 reported on 30 knees at an average follow-up of 6.75 years. They had 28 excellent and 1 good results, with mean objective and functional Knee Society scores of 93 and 86 points, respectively. Survivorship was 94%, and 2 patients reported occasional anterior knee pain. Parvizi and coworkers5 reported on 31 knees at an average follow-up of 5.2 years. They had 94% survivorship with mean objective and functional knee society scores of 89. Five patients reported continued mild anterior knee pain and 1 rated it as moderate. Twenty-one patients required lateral release and 3 required more-extensive realignment. Dalury6 reported on 33 knees at average follow-up of 5.2 years. No cases had been revised and mean Knee Society pain and function results were 48 and 96 points, respectively. Lastly, Thompson and coworkers7 treated 33 knees in 31 patients with isolated patellofemoral arthritis with TKA and unresurfaced patellas. They reported their findings at an average follow-up of 1.7 years and found 100% survivorship, with 21 knees being pain free and 12 cases reporting occasional anterior knee pain.
1. No attempt at nonoperative care to rule out other sources of pain 2. Arthritis of greater than Grade I Kellgren-Lawrence involving the tibiofemoral joint 3. Systemic inflammatory arthritis 4. Osteoarthritis/chondrosis of the patellofemoral joint of Grade III or less 5. Patella baja 6. Uncorrected patellofemoral instability or malalignment 7. Uncorrected tibiofemoral mechanical malalignment (valgus > 8° or varus > 5°). 8. Active infection 9. Evidence of chronic regional pain syndrome 10. Fixed loss of knee range of motion (minimum of –10° extension and 110° flexion) 11. Psychogenic pain
Patellofemoral Arthroplasty Although TKA has been shown to produce reliable and durable results for the treatment of isolated patellofemoral arthritis, many surgeons have reservations about performing such an extensive procedure for arthritis isolated to one compartment, especially in younger patients. Because of this, attempts at producing prostheses to selectively resurface the patellofemoral compartment have been undertaken. Current indications and contraindications listed in the literature for PFA are listed in Tables 2 and 3, respectively.16 The most
* Adapted from Leadbetter WB, Seyler TM, Ragland PS, et al: J Bone Joint Surg Am 88:122-137, 2006.16
common cause of failure with first-generation designs of PFA was patellar maltracking because of inadequate geometric features of the trochlear design. More contemporary designs appear to have addressed this problem, and now the most common cause of revision is progression of tibiofemoral arthritis.27 Importantly, PFA does not appear to compromise the results of TKA if conversion is required.40 The first patellofemoral prosthesis was developed in the 1950s by McKeever.8 This was a Vitalium shell fixed to the undersurface of the patella with a transverse screw (Fig. 1). The femoral portion was left unresurfaced. Results with this prosthesis were mixed, with roughly 75% of patients having good to satisfactory results at follow-up of 5-20 years.9,10 The procedure was largely abandoned because of concerns of trochlear wear.
Table 2 Indications for Patellofemoral Arthroplasty* 1. Degenerative arthritis isolated to the patellofemoral joint 2. Severe symptoms of patellofemoral joint degeneration affecting activities of daily living and/or failed prior conservative procedures 3. Posttraumatic osteoarthritis 4. Extensive Grade III chondromalacia of the patellofemoral joint 5. Failure of previous extensor mechanism unloading procedure 6. Patellofemoral malalignment/dysplasia-induced degeneration *Adapted from Leadbetter WB, Seyler TM, Ragland PS, et al: J Bone Joint Surg Am 88:122-137, 2006.
Figure 1 The McKeever prosthesis (McKeever DC: Patellar prosthesis. J Bone Joint Surg 37A:1074-1084, 1955). (Color version of figure is available online.)
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ciety scores of 77% excellent, 14% fair, and 9% failure. The primary long-term mode of failure was tibiofemoral arthritis. More recently several manufacturers have come out with contemporary PFA systems.16 The trochlear components of these systems have been designed to avoid the patellar tracking problems associated with previous prostheses, and the instrumentation for these systems is much more sophisticated, improving the precision of implant placement.12 Currently, there are no published long-term series with these contemporary prostheses; however short-term results appear to be encouraging, with good to excellent results ranging from 83 to 100% at average follow-up ranging 2-6 years.16-20
Our Series
Figure 2 The natural knee II Patello-femoral joint system (Leadbetter WB, Seyler TM, Ragland PS, et al: Indications, contraindications, and pitfalls of patellofemoral arthroplasty. J Bone Joint Surg Am 88:122-137, 2006). (Color version of figure is available online.)
Several decades later, two patellofemoral prostheses were introduced that resurfaced both the patellar and trochlear surfaces of the joint: the Lubinus and the Richards I and II. Results with these prostheses were largely mixed, but overall the Lubinus faired poorly because of patellofemoral tracking problems secondary to the design of the trochlear component.27 It had a large radius of curvature and a narrow medialto-lateral diameter, as well as limited extension into the proximal portion of the joint. The latter predisposed to component malposition and patellar maltracking, and it also led to catching of the patellar component in the first 30° of flexion.11,12 Published results with this prosthesis revealed satisfactory outcomes in 45-84% of patients, with follow-up ranging from 19 months to 7.5 years.27,11,13-15 Tauro and coworkers13 reported conversion to TKA or alternative PFA in 28% of patients at average 7.5 years, and Board and coworkers15 reported conversion to TKA in 24% of patients at average of 19 months. The most common cause of failure was patellar maltracking, followed by progression of tibiofemoral arthritis. Results with the Richards I and II devices were more encouraging, with good to excellent outcomes ranging from 72 to 88%, with follow-up ranging from 4 to 17 years.27,41,42 Several long-term studies with encouraging results have been published. Kooijman and coworkers41 reported on 56 PFAs performed for isolated patellofemoral arthritis, with 45 knees available for follow-up at an average of 17 years. Eighty-six percent of patients had a good or excellent outcome, and 75% of PFAs were still surviving. Twelve knees had additional surgery for tibiofemoral arthritis: 2 underwent high tibial osteotomy and 10 knees were successfully converted to TKA at an average time of 15.6 years. Cartier and coworkers42 reported on 79 PFAs at a minimum and an average follow-up of 6 and 10 years, respectively. Many patients underwent concomitant procedures for realignment and a large number of patients had been lost to follow-up. Nonetheless, they reported 75% prosthetic survivorship and clinical Knee So-
Thus far, no reports in the literature exist on use of the Natural Knee II Patello-femoral Joint System (Zimmer, Warsaw, IN; Fig. 2). We have been implanting this prosthesis at our institution since April 2004 and have retrospectively reviewed our first 34 patients and 40 knees. The study was approved by our Institutional Review Board. All patients underwent PFA for symptomatic patellofemoral arthritis that was recalcitrant to nonoperative management. All patients had radiographic evidence of knee arthritis that was limited to the patellofemoral joint. The etiology of the patellofemoral arthritis was due to patellar maltracking, subluxation, or prior trauma. Figures 3 and 4 show pre- and postoperative radiographs of a typical patient. The average patient age in this series was 61 years and ranged from 34 to 84 years of age, and average duration of follow-up was 30 months. Outcome measures included the Knee Injury and Osteoarthritis Outcome Score (KOOS), Tegner scores, patient satisfaction, and implant survivorship. At most recent follow-up, all 40 (100%) knees were classified as satisfactory by the patients. The average subset KOOS scores were 93 for pain, 94 for symptoms, 94 for
Figure 3 Preoperative anteroposterior, lateral, and Merchant views of a typical patient showing marked arthritis isolated to the patellofemoral joint.
Patellofemoral replacment
Figure 4 Postoperative anteroposterior, lateral, and Merchant views of the same patient.
ADLs, 70 for sports and recreation, and 82 for quality of life. The average preoperative Tegner score was 2.6, increasing to 4.7 postoperatively. Thirty-eight of 40 prostheses survived over the follow-up interval. Two cases underwent revision surgery for traumatic injuries. The first case involved a medial retinacular injury after falling and was treated effectively with retinacular repair, lateral release, and further medialization of the patellar component. The second patient sustained a blunt traumatic injury while mountain biking that dislodged the femoral component. It was effectively treated with revision of the femoral component. There were no revisions to TKA. At most recent follow-up, there was no progression of osteoarthritis to involve the tibiofemoral compartments and no evidence of component loosening.
Conclusion Isolated patellofemoral arthritis is a common problem experienced by patients and encountered by orthopedic surgeons. Unfortunately, nonoperative and nonarthroplasty forms of surgical treatment have failed to provide good and lasting pain relief to patients, especially in the setting of advanced arthritis. While TKA is a reliable form of treatment for isolated patellofemoral arthritis, many patients and physicians are hesitant to proceed with such a drastic operation for a unicompartmental problem. In properly selected patients, PFA has been shown to be a viable treatment option for the treatment of isolated patellofemoral arthritis without compromising revision to TKA if required. Results of more contemporary prostheses, including the Natural Knee II Patellofemoral Joint System, appear encouraging in short-term follow-up. Long-term outcome studies and prospective trials comparing TKA to PFA are needed.
References 1. Davies AP, Vince AS, Shepstone L, et al: The radiologic prevalence of patellofemoral osteoarthritis. Clin Orthop 402:206-212, 2002
33 2. McAlindon TE, Snow S, Cooper C, et al: Radiographic pattern of osteoarthritis of the knee joint in the community: The importance of the patello-femoral joint. Ann Rheum Dis 51:844-849, 1992 3. Laskin RS, van Steijn M: Total knee replacement for patients with patellofemoral arthritis. Clin Orthop Relat Res 367:89-95, 1999 4. Mont MA, Haas S, Mullick T, et al: Total knee arthroplasty for patellofemoral arthritis. J Bone Joint Surg Am 84:1977-1981, 2002 5. Parvizi J, Stuart MJ, Pagnano MW, et al: Total knee arthroplasty in patients with isolated patellofemoral arthritis. Clin Orthop Relat Res 392:147-152, 2001 6. Dalury DF: Total knee replacement for patellofemoral disease. J Knee Surg 18:274-277, 2005 7. Thompson NW, Ruiz AL, Breslin E, et al: Total knee arthroplasty without patellar resurfacing in isolated patellofemoral osteoarthritis. J Arthroplasty 16:607-612, 2001 8. McKeever DC: Patellar prosthesis. J Bone Joint Surg Am 37:1074-1084, 1955 9. Harrington KD: Long-term results for the McKeever patellar resurfacing prosthesis used as a salvage procedure for severe chondromalacia patellae. Clin Orthop Relat Res 279:201-213, 1992 10. Pickett JC, Stoll DA: Patellaplasty or patellectomy? Clin Orthop Relat Res 144:103-106, 1979 11. Lonner JH: Patellofemoral arthroplasty: Pros, cons, and design considerations. Clin Orthop Relat Res 428:158-165, 2004 12. Lonner JH: Patellofemoral arthroplasty: The impact of design on outcomes. Orthop Clin North Am 39:347-354, 2008 13. Tauro B, Ackroyd CE, Newman JH, et al: The Lubinus patellofemoral arthroplasty: A 2-to 18-year follow-up study. J Bone Joint Surg Br 83:696-701, 2001 14. Smith AM, Peckett WR, Butler-Manuel PA, et al: Treatment of patellofemoral arthritis using the Lubinus patello-femoral arthroplasty: A retrospective review. Knee 9:27-30, 2002 15. Board TN, Mahmood A, Ryan WG, et al: The Lubinus patellofemoral arthroplasty: A series of 17 cases. Arch Orthop Trauma Surg 124:285287, 2004 16. Leadbetter WB, Seyler TM, Ragland PS, et al: Indications, contraindications, and pitfalls of patellofemoral arthroplasty. J Bone Joint Surg Am 88:122-137, 2006 17. Ackroyd CE, Newman JH: The Avon patellofemoral arthroplasty: Twofive years results. J Bone Joint Surg Br 85:162-163, 2003 (suppl II) 18. Ackroyd CE, Chir B: Development and early results of a new patellofemoral arthroplasty. Clin Orthop Relat Res 436:7-13, 2005 19. Merchant AC: Early results with a total patellofemoral joint replacement arthroplasty prosthesis. J Arthroplasty 19:829-836, 2004 20. Sisto DJ, Sarin VK: Custom patellofemoral arthroplasty of the knee. J Bone Joint Surg Am 88:1475-1480, 2006 21. Greslamer RP, Dejour D, Gould J: The pathophysiology of patellofemoral arthritis. Orthop Clin North Am 39:269-274, 2008 22. Iwano T, Kurosawa H, Tokuyama, et al: Roentgenographic and clinical findings of patellofemoral osteoarthrosis: With special reference to its relationship to femorotibial osteoarthrosis and etiologic factors. Clin Orthop Relat Res 252:190-197, 1990 23. Dejour D, Allain J: Histoire naturelle de l’arthrose femoro-patella ire isolee. Rev Chir Orthop 90:1S, 69-129, 2004 (suppl 5) 24. Argenson JN, Flecher X, Parratte S, et al: Patellofemoral arthroplasty: An update. Clin Orthop Relat Res 440:50-53, 2005 25. Greslamer RP, Stein DA: Patellofemoral arthritis. J Bone Joint Surg Am 88:1849-1861, 2006 26. Merchant AC, Mercer RC, Jacobsen RH, et al: Roentgenographic analysis of patellofemoral congruence. J Bone Joint Surg Am 56:1391, 1974 27. Lonner JH: Patellofemoral arthroplasty. J Am Acad Orthop Surg 15: 495-506, 2007 28. Lotke PA, Lonner JH, Nelson CL: Patellofemoral arthroplasty: The third compartment. J Arthroplasty 20:4-6, 2005 (suppl 2) 29. Aderinto J, Cobb AG: Lateral release for patellofemoral arthritis. Arthroscopy 18:399-403, 2002 30. Schepsis AA, DeSimone AA, Leach RE: Anterior tibial tubercle transposition for patellofemoral arthrosis. Am J Knee Surg 7:13-20, 1994 31. Heatley FW, Allen PR, Patrick JH: Tibial tubercle advancement for
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32.
33.
34.
35.
36.
anterior knee pain. A temporary or permanent solution. Clin Orthop Relat Res 208:215-224, 1986 Jenny JY, Sader Z, Henry A, et al: Elevation of the tibial tubercle for patellofemoral pain syndrome: An 8-to 15-year follow-up. Knee Surg Sports Traumatol Arthrosc 4:92-96, 1996 Fulkerson JP: Anteromedialization of the tibial tuberosity for patellofemoral malalignment. Clin Orthop Relat Res 177:176-181, 1983 Pidoriano AJ, Weinstein RN, Buuck DA, et al: Correlation of patellar articular lesions with results from anteromedial tibial tubercle transfer. Am J Sports Med 25:533-537, 1997 Brittberg M, Lindahl A, Nilsson A, et al: Treatment of deep cartilage defects in the knee with autologous chondrocyte transplantation. N Engl J Med 331:889-895, 1994 Minas T, Bryant T: The role of autologous chondrocyte implantation in the patellofemoral joint. Clin Orthop Relat Res 436:30-39, 2005
37. Compere CL, Hill JA, Lewinnek GE, et al: A new method of patellectomy for patellofemoral arthritis. J Bone Joint Surg Am 61:714718, 1979 38. Baker CL, Hughston JC: Miyakawa patellectomy. J Bone Joint Surg Am 70:1489-1494, 1988 39. Compere CL, Hill JA, Lewinnek GE, et al: A new method of patellectomy for patellofemoral arthritis. J Bone Joint Surg Am 61:714-718, 1979 40. Lonner JH, Jasko JG, Booth RE: Revision of the failed patellofemoral arthroplasty to total knee arthroplasty. J Bone Joint Surg Am 88:23372342, 2006 41. Kooijman HJ, Driessen JR, Van Horn JR: Long-term results of patellofemoral arthroplasty: A report of 56 arthroplasties with 17 years of follow-up. J Bone Joint Surg Br 85:836-840, 2003 42. Cartier P, Sanouiller JL, Grelsamer R: Patello-femoral arthroplasty: 2-12 years follow-up study. J Arthroplasty 5:49-55, 1990
I
solated patellofemoral arthritis is a common problem among orthopedic patients, affecting approximately 11% of men and 24% of women over the age of 55 years.1,2 Despite the high prevalence of this condition, no clear consensus exists within the orthopedic community as to how best to treat this condition. Nonoperative forms of treatment tend to be ineffective or only provide temporary relief, and many forms of operative treatment have disappointing outcomes. Total knee arthroplasty (TKA) has been shown to provide effective and lasting pain relief for isolated patellofemoral arthritis,3-7 however many patients and physicians have reservations in performing such an invasive procedure for a unicompartmental condition. Patellofemoral arthroplasty (PFA) has been performed for over 50 years for isolated patellofemoral arthritis and initially had poor results with high complication rates.8-15 In recent times, newer prosthetic designs have been shown to produce reliably good results with high rates of survivorship in the short term.16-20 The following article reviews isolated patellofemoral arthritis, with special emphasis on how PFA pertains to its treatment. Finally, the shortterm results of the anatomically designed Natural Knee II Patello-femoral Joint System will be presented.
*Department of Orthopaedics, University of Utah, Salt Lake City, UT, USA. †Oklahoma Sports and Orthopedics Institute, Edmond, OK, USA. ‡1705 Warren Avenue, Williamsport, PA, USA. Address reprint requests to A.A. Hofmann, MD, University of Utah, Department of Orthopaedics, 590 Wakara Way, Salt Lake City, UT 84108. E-mail: [email protected]
1045-4527/09/$-see front matter © 2009 Published by Elsevier Inc. doi:10.1053/j.sart.2008.11.014
Epidemiology and Etiology Isolated patellofemoral arthritis is a common problem. Epidemiologic studies have shown that 11% of men and 24% of women older than 55 years of age with symptomatic arthritis have disease isolated to the patellofemoral joint.2 Similar findings have been published on orthopedic outpatients over the age of 40, wherein 9.2% of patients presenting with knee pain had radiographic signs of isolated patellofemoral arthritis.1 Much like a varus knee, patellofemoral arthritis commonly stems from problems with malalignment, but it can also be associated with other conditions including dysplasia, instability, trauma, inflammatory arthritis, and osteoarthritis.21 Malalignment can stem from a tight lateral retinaculum, an abnormal Q angle, or abnormal femoral torsion. All of these manifest in excessive pressure on the lateral aspect of the patella and pose an increased risk for the development of arthritis over time.22 Patellofemoral dysplasia also contributes to malalignment and is strongly associated with the development of patellofemoral arthritis.4,5 Dejour and Allain23 found it to be the most common predisposing factor, with 78% of patients having radiographic signs of trochlear dysplasia. Higher grades of arthritis have also been correlated to higher grades of dysplasia.22 Patellar dislocation and trauma are also common causes. In fact nearly one-third of patellofemoral arthroplasties in one series were performed in patients with previous trauma.21,24 Osteoarthritis and inflammatory conditions can also manifest by first involving the patellofemoral joint, and careful attention to the tibiofemoral compartments should be paid before proceeding with isolated patellofemoral procedures. 29
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Clinical Presentation and Diagnosis When arthritic changes of the patellofemoral joint are present on radiographs, it is easy to assign this as the cause of a patient’s knee pain. However, it must be kept in mind that there are several causes of anterior knee pain and arthritis may not be the cause. These conditions include referred pain from the hip or spine, overuse syndromes (tendonitis), synovitis, bursitis, and neoplastic processes.25 With a careful clinical evaluation, these causes can be ruled out. Patients with isolated patellofemoral arthritis commonly complain of knee pain that is anterior in nature. Pain is typically aggravated by activities that increase the load across the patellofemoral joint, such as rising from a chair, climbing and descending stairs, or squatting. It is typically relieved by activities that decrease the load, such as walking on level ground and sitting with the knee extended. Often times the knee pain may extend back to adolescence and a history of prior patellar dislocations or subluxations may be present. Pain that is more global or located in the medial and lateral compartments of the knee is more indicative of systemic knee arthritis. Physical examination findings will typically reveal crepitus and tenderness about the patellofemoral joint and tenderness under the lateral facet. Many patients will have patellar tracking abnormalities evident during active range of motion testing and often the patella will point inward with standing.25 Palpation of the quadriceps and patellar tendons as well as the prepatellar bursa should be performed, as well as a hip examination, to rule out referred pain. Tenderness present at the medial or lateral joint line should alert the examiner of the possibility of more diffuse arthritis. Plain radiographs are typically sufficient for the work-up of patellofemoral arthritis. Weight-bearing anteroposterior and midflexion views should be obtained to rule out tibiofemoral disease. The diagnosis is most easily made on the lateral and Merchant26 views, where joint space narrowing and osteophyte formation will be evident, particularly on the lateral side. Trochlear dysplasia and abnormal patellar tilt should be noted, as these can provide evidence that the arthritis is not from a more systemic cause that has simply involved the patellofemoral joint first.
Treatment Options Nonoperative Treatment Most authors recommend a trial of nonoperative treatment for patients with patellofemoral arthritis, especially in mild to moderate cases. Treatment options include activity modification, quadriceps strengthening, bracing, nonsteroidal antiinflammatories, glucosamine– chondroitin, and viscosupplementation.25 Unfortunately, none of these have been proven to be markedly effective, especially in the setting of advanced arthritis.25-28
Operative Treatment Excluding Arthroplasty Surgical intervention is often indicated for those patients who fail nonoperative treatment and have pain that is disabling.
Table 1 Possible Surgical Solutions for Isolated Patellofemoral Arthritis Arthroscopic debridement Microfracture articular restoration Lateral release Soft tissue realignment Osteotomies of the tibial tubercle
Mosaicplasty/ACI Lateral patella partial facetectomy Patellectomy Patellofemoral arthroplasty Total knee arthroplasty
There are numerous proposed surgical treatment options for patellofemoral arthritis (Table 1). Lateral release, which is commonly employed for patellar maltracking, has also been used for the treatment of isolated patellofemoral arthritis, and results have been less than encouraging. Aderinto and Cobb29 studied 54 knees treated with lateral release, 26 of which had isolated patellofemoral arthritis. They found that only 50% of the patients were satisfied with the procedure and 4 were converted to TKA within 18 months. Osteotomies of the tibial tubercle have been studied for treatment of patellofemoral arthritis as well, and unfortunately they have not provided good results either. The Maquet operation, a straight anterior transfer of the tuberosity, has been used by several authors to treat patellofemoral arthritis.30-32 Heatley and coworkers31 reported on 14 knees with patellofemoral arthritis and, at 6-year follow-up, 6 knees were rated good to excellent, 3 fair, and the remaining 5 poor. The procedure also has number of complications, including skin necrosis, osteotomy fragment fracture, patellar tendonitis, as well as a painful prominence.30,31 The Fulkerson osteotomy, anteromedialization of the tibial tubercle, has also been studied. This operation is more appealing in that it unloads the lateral aspect of the patella; however, it is more technically demanding to perform.33 Results have been similar to the Maquet osteotomy, but improved results have been reported for arthritis isolated to the lateral facet of the patella, rather than complete involvement of the articulation.34 Results of autologous chondrocyte implantation used to treat patellofemoral arthritis were initially quite poor;35 however, more recent investigations have found somewhat improved results, with most patients reporting good pain relief and improved function.36 Fairly high graft failure rates are still reported, nearly 20%, and most of these patients were young without systemic involvement of the patellofemoral joint. The high cost of this procedure is of significant concern. Patellectomy has been used to treat patellofemoral disease for nearly 100 years. Analyzing the data for patellectomy is difficult, as much of it is conflicting and patient populations are quite heterogeneous. The most recent studies show that it is likely an effective pain-relieving procedure,37,38 but most surgeons tend to avoid it because of its irreversible nature and the marked reduction in extensor mechanism strength that occurs. If performed, tubularization of the extensor mechanism is recommended.39
Patellofemoral replacment
31
Total Knee Arthroplasty
Table 3 Contraindications to Patellofemoral Arthroplasty
Total knee arthroplasty has been well studied in the treatment of isolated patellofemoral arthritis, and all studies report high rates of survivorship and large percentages of good to excellent results in short- to midterm follow-up. Laskin and van Steijn3 studied 53 knees at an average follow-up of 7.4 years. They reported that 81% of patients had good to excellent results, with mean Knee Society scores of 47 and 96 points for pain and function, respectively. The overall survivorship was 98%, with 1 knee requiring revision and 1 patient undergoing above-knee amputation. Mont and coworkers4 reported on 30 knees at an average follow-up of 6.75 years. They had 28 excellent and 1 good results, with mean objective and functional Knee Society scores of 93 and 86 points, respectively. Survivorship was 94%, and 2 patients reported occasional anterior knee pain. Parvizi and coworkers5 reported on 31 knees at an average follow-up of 5.2 years. They had 94% survivorship with mean objective and functional knee society scores of 89. Five patients reported continued mild anterior knee pain and 1 rated it as moderate. Twenty-one patients required lateral release and 3 required more-extensive realignment. Dalury6 reported on 33 knees at average follow-up of 5.2 years. No cases had been revised and mean Knee Society pain and function results were 48 and 96 points, respectively. Lastly, Thompson and coworkers7 treated 33 knees in 31 patients with isolated patellofemoral arthritis with TKA and unresurfaced patellas. They reported their findings at an average follow-up of 1.7 years and found 100% survivorship, with 21 knees being pain free and 12 cases reporting occasional anterior knee pain.
1. No attempt at nonoperative care to rule out other sources of pain 2. Arthritis of greater than Grade I Kellgren-Lawrence involving the tibiofemoral joint 3. Systemic inflammatory arthritis 4. Osteoarthritis/chondrosis of the patellofemoral joint of Grade III or less 5. Patella baja 6. Uncorrected patellofemoral instability or malalignment 7. Uncorrected tibiofemoral mechanical malalignment (valgus > 8° or varus > 5°). 8. Active infection 9. Evidence of chronic regional pain syndrome 10. Fixed loss of knee range of motion (minimum of –10° extension and 110° flexion) 11. Psychogenic pain
Patellofemoral Arthroplasty Although TKA has been shown to produce reliable and durable results for the treatment of isolated patellofemoral arthritis, many surgeons have reservations about performing such an extensive procedure for arthritis isolated to one compartment, especially in younger patients. Because of this, attempts at producing prostheses to selectively resurface the patellofemoral compartment have been undertaken. Current indications and contraindications listed in the literature for PFA are listed in Tables 2 and 3, respectively.16 The most
* Adapted from Leadbetter WB, Seyler TM, Ragland PS, et al: J Bone Joint Surg Am 88:122-137, 2006.16
common cause of failure with first-generation designs of PFA was patellar maltracking because of inadequate geometric features of the trochlear design. More contemporary designs appear to have addressed this problem, and now the most common cause of revision is progression of tibiofemoral arthritis.27 Importantly, PFA does not appear to compromise the results of TKA if conversion is required.40 The first patellofemoral prosthesis was developed in the 1950s by McKeever.8 This was a Vitalium shell fixed to the undersurface of the patella with a transverse screw (Fig. 1). The femoral portion was left unresurfaced. Results with this prosthesis were mixed, with roughly 75% of patients having good to satisfactory results at follow-up of 5-20 years.9,10 The procedure was largely abandoned because of concerns of trochlear wear.
Table 2 Indications for Patellofemoral Arthroplasty* 1. Degenerative arthritis isolated to the patellofemoral joint 2. Severe symptoms of patellofemoral joint degeneration affecting activities of daily living and/or failed prior conservative procedures 3. Posttraumatic osteoarthritis 4. Extensive Grade III chondromalacia of the patellofemoral joint 5. Failure of previous extensor mechanism unloading procedure 6. Patellofemoral malalignment/dysplasia-induced degeneration *Adapted from Leadbetter WB, Seyler TM, Ragland PS, et al: J Bone Joint Surg Am 88:122-137, 2006.
Figure 1 The McKeever prosthesis (McKeever DC: Patellar prosthesis. J Bone Joint Surg 37A:1074-1084, 1955). (Color version of figure is available online.)
A.A. Hofmann et al.
32
ciety scores of 77% excellent, 14% fair, and 9% failure. The primary long-term mode of failure was tibiofemoral arthritis. More recently several manufacturers have come out with contemporary PFA systems.16 The trochlear components of these systems have been designed to avoid the patellar tracking problems associated with previous prostheses, and the instrumentation for these systems is much more sophisticated, improving the precision of implant placement.12 Currently, there are no published long-term series with these contemporary prostheses; however short-term results appear to be encouraging, with good to excellent results ranging from 83 to 100% at average follow-up ranging 2-6 years.16-20
Our Series
Figure 2 The natural knee II Patello-femoral joint system (Leadbetter WB, Seyler TM, Ragland PS, et al: Indications, contraindications, and pitfalls of patellofemoral arthroplasty. J Bone Joint Surg Am 88:122-137, 2006). (Color version of figure is available online.)
Several decades later, two patellofemoral prostheses were introduced that resurfaced both the patellar and trochlear surfaces of the joint: the Lubinus and the Richards I and II. Results with these prostheses were largely mixed, but overall the Lubinus faired poorly because of patellofemoral tracking problems secondary to the design of the trochlear component.27 It had a large radius of curvature and a narrow medialto-lateral diameter, as well as limited extension into the proximal portion of the joint. The latter predisposed to component malposition and patellar maltracking, and it also led to catching of the patellar component in the first 30° of flexion.11,12 Published results with this prosthesis revealed satisfactory outcomes in 45-84% of patients, with follow-up ranging from 19 months to 7.5 years.27,11,13-15 Tauro and coworkers13 reported conversion to TKA or alternative PFA in 28% of patients at average 7.5 years, and Board and coworkers15 reported conversion to TKA in 24% of patients at average of 19 months. The most common cause of failure was patellar maltracking, followed by progression of tibiofemoral arthritis. Results with the Richards I and II devices were more encouraging, with good to excellent outcomes ranging from 72 to 88%, with follow-up ranging from 4 to 17 years.27,41,42 Several long-term studies with encouraging results have been published. Kooijman and coworkers41 reported on 56 PFAs performed for isolated patellofemoral arthritis, with 45 knees available for follow-up at an average of 17 years. Eighty-six percent of patients had a good or excellent outcome, and 75% of PFAs were still surviving. Twelve knees had additional surgery for tibiofemoral arthritis: 2 underwent high tibial osteotomy and 10 knees were successfully converted to TKA at an average time of 15.6 years. Cartier and coworkers42 reported on 79 PFAs at a minimum and an average follow-up of 6 and 10 years, respectively. Many patients underwent concomitant procedures for realignment and a large number of patients had been lost to follow-up. Nonetheless, they reported 75% prosthetic survivorship and clinical Knee So-
Thus far, no reports in the literature exist on use of the Natural Knee II Patello-femoral Joint System (Zimmer, Warsaw, IN; Fig. 2). We have been implanting this prosthesis at our institution since April 2004 and have retrospectively reviewed our first 34 patients and 40 knees. The study was approved by our Institutional Review Board. All patients underwent PFA for symptomatic patellofemoral arthritis that was recalcitrant to nonoperative management. All patients had radiographic evidence of knee arthritis that was limited to the patellofemoral joint. The etiology of the patellofemoral arthritis was due to patellar maltracking, subluxation, or prior trauma. Figures 3 and 4 show pre- and postoperative radiographs of a typical patient. The average patient age in this series was 61 years and ranged from 34 to 84 years of age, and average duration of follow-up was 30 months. Outcome measures included the Knee Injury and Osteoarthritis Outcome Score (KOOS), Tegner scores, patient satisfaction, and implant survivorship. At most recent follow-up, all 40 (100%) knees were classified as satisfactory by the patients. The average subset KOOS scores were 93 for pain, 94 for symptoms, 94 for
Figure 3 Preoperative anteroposterior, lateral, and Merchant views of a typical patient showing marked arthritis isolated to the patellofemoral joint.
Patellofemoral replacment
Figure 4 Postoperative anteroposterior, lateral, and Merchant views of the same patient.
ADLs, 70 for sports and recreation, and 82 for quality of life. The average preoperative Tegner score was 2.6, increasing to 4.7 postoperatively. Thirty-eight of 40 prostheses survived over the follow-up interval. Two cases underwent revision surgery for traumatic injuries. The first case involved a medial retinacular injury after falling and was treated effectively with retinacular repair, lateral release, and further medialization of the patellar component. The second patient sustained a blunt traumatic injury while mountain biking that dislodged the femoral component. It was effectively treated with revision of the femoral component. There were no revisions to TKA. At most recent follow-up, there was no progression of osteoarthritis to involve the tibiofemoral compartments and no evidence of component loosening.
Conclusion Isolated patellofemoral arthritis is a common problem experienced by patients and encountered by orthopedic surgeons. Unfortunately, nonoperative and nonarthroplasty forms of surgical treatment have failed to provide good and lasting pain relief to patients, especially in the setting of advanced arthritis. While TKA is a reliable form of treatment for isolated patellofemoral arthritis, many patients and physicians are hesitant to proceed with such a drastic operation for a unicompartmental problem. In properly selected patients, PFA has been shown to be a viable treatment option for the treatment of isolated patellofemoral arthritis without compromising revision to TKA if required. Results of more contemporary prostheses, including the Natural Knee II Patellofemoral Joint System, appear encouraging in short-term follow-up. Long-term outcome studies and prospective trials comparing TKA to PFA are needed.
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