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British Columbia Medical Journal - November 2010: Knee replacement



2010 issue

2010 issue

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British Columbia Medical Journal - November 2010: Knee replacement British Columbia Medical Journal - November 2010: Knee replacement Document Transcript

  • Robert C. Schweigel, MD, FRCSC Partial knee replacement The last decade has seen renewed interest in unicondylar knee arthroplasty and patellafemoral arthroplasty for patients with osteoarthritis affecting one compartment of the knee. artial knee replacements nent that goes on the femoral condyle, P ABSTRACT: Partial knee replace- ments have come into and out of are a form of knee arthro- and another component that goes on favor over the past 60 years. There plasty that doesn’t replace the tibial side. The tibial component has been renewed interest in partial the entire knee (the femoral can be metal-backed with a fixed- knee replacements in the armamen- condyles, tibial plateau, and patella). bearing or mobile-bearing polyethyl- tarium for arthritic knees due to These surgical interventions include ene bearing surface, or it can be an all- increasingly good results. Partial the patellofemoral arthroplasty and polyethylene fixed-bearing cemented knee replacements include the uni- the more common unicondylar knee component. There is no evidence that condylar knee replacement and the arthroplasty. Both procedures have one approach is better than another. patellofemoral arthroplasty. These been available since the 1950s and The rationale for considering a partial knee replacements are indicat- may be options for patients who have unicondylar knee arthroplasty is that ed for specific, isolated arthritic por- osteoarthritis in one compartment of it is a more conservative operation tions of the knee joint—specifically the knee, do not have specific con- with faster recovery, less resection of the medial, lateral, or patellofemoral traindications for these more conser- bone, conservation of the cruciate lig- portion of the joint. In carefully vative procedures, and who have aments, and potentially better func- selected patients outcomes are com- failed to benefit from nonoperative tion. In addition, conversion to a total parable to the results of total knee management of their osteoarthritis. knee replacement down the road is replacements. Patient selection and simple using modern techniques, with meticulous surgical technique are Unicondylar knee outcomes similar to a primary knee likely the key to a good result in a par- arthroplasty replacement. When appropriate, par- tial knee replacement. In the past, unicondylar knee replace- tial knee arthroplasty can be thought ments fell out of favor primarily be- of as a time-buying operation. cause of the surgical technique of the In addition, a unicondylar knee time, which made conversion to a full replacement is an alternative to other knee replacement difficult. However, invasive procedures such as a high with the advent of minimally invasive tibial osteotomy or a total knee approaches for unicondylar knee replacement. replacement, there has been renewed interest in this procedure over the past decade. Dr Schweigel is a clinical instructor in the A unicondylar knee replacement Department of Orthopaedics at the Univer- ( Figure 1 ) consists of a metal compo- sity of British Columbia. 442 BC MEDICAL JOURNAL VOL. 52 NO. 9, NOVEMBER 2010 www.bcmj.org
  • Partial knee replacement A B Figure 1. (A) Anteroposterior radiograph showing a medial unicondylar knee replacement. (B) Lateral radiograph showing a medial unicondylar knee replacement. Radiographs courtesy of Dr Bas Masri. Patient selection lateral or medial unicondylar knee lar deformity had to be less than 15 Careful patient selection is needed to replacement, the presence of substan- degrees and be passively correctible get the best possible results. This re- tial patellofemoral pain is a con- to neutral at the time of operation. quires a thorough history and physical traindication. In addition, the pain has Specific contraindications to a uni- examination. to be of sufficient magnitude and to condylar knee arthroplasty identified The history should include specif- interfere with activities of daily living by Kozinn and Scott included the ic questions about the knee to deter- to warrant surgical intervention. It is diagnosis of an inflammatory arthri- mine whether there was a gradual important to ensure that all reasonable tis, age younger than 60 years, high onset of pain or whether there was a attempts at medical management have patient activity level, pain at rest (which specific incident (i.e., trauma) that been exhausted before considering may indicate an inflammatory com- caused the problem. This is particu- any surgical procedure. ponent), and patellofemoral pain or larly important because anterior cru- exposed bone in the patellofemoral or ciate ligament deficiency is a con- Indications opposite compartment at the time of traindication for a unicondylar knee Kozinn and Scott have outlined several the surgery. Asymptomatic chondro- replacement. When considering a uni- classic indications and contraindica- malacia in the patellofemoral joint condylar knee replacement, the loca- tions for unicondylar knee replace- was not necessarily a contraindication. tion of the pain is very important. It ment.1 Indications include the diagno- More recently, some of these indi- must be localized to only one com- sis of unicondylar osteoarthritis or cations have been expanded. Various partment of the knee. For a medial uni- osteonecrosis in either the medial or authors have reported good results in condylar knee replacement, the pain lateral compartment of the knee. Ini- patients younger than 60 years2 and in has to be medial and the patient has to tially, Kozinn and Scott stipulated that obese patients with BMIs over 30.3 be able to point to the medial side of patient age had to be greater than 60 Generally it is felt that both of the the knee as the site of the pain. For a years and weight had to be less than cruciate ligaments have to be intact to lateral unicondylar knee replacement, 82 kg. There had to be minimal pain at perform a unicondylar knee arthro- which is much less common as the rest and low demand of activity. The plasty. Again however, studies have results are less predictable than a ideal range of motion was an arc of suggested that a medial compartment medial unicondylar knee replacement, flexion of 90 degrees with a contrac- unicondylar arthroplasty is possible the pain has to be lateral. For either a ture of less than 5 degrees. The angu- in an ACL-deficient knee in certain www.bcmj.org VOL. 52 NO. 9, NOVEMBER 2010 BC MEDICAL JOURNAL 443
  • Partial knee replacement A B Figure 2: (A) Anteroposterior radiograph showing a patellofemoral replacement. (B) Lateral radiograph showing a patellofemoral replacement. Radiographs courtesy of Dr Bas Masri. circumstances;4 still, most surgeons Based on the above, it is clear that or good outcome in 92% of patients.5 will not perform a unicondylar knee not every patient with knee osteo- Most recently Newman and col- replacement on a patient with a histo- arthritis is a candidate for a unicondy- leagues6 compared unicondylar knee ry of torn ACL, and the presence of lar knee replacement, and the final replacement with total knee replace- a torn ACL should be considered a decision is up to the orthopaedic sur- ment in a prospective randomized contraindication to a unicondylar knee geon. Typically, only 10% to 20% of control trial. This report stated that the replacement. patients undergoing knee replacement 15-year survivorship for a unicondy- In summary, in addition to well- are candidates for unicondylar knee lar knee replacement was close to 90% localized pain with no patellofemoral arthroplasty. compared with 80% for a total knee involvement, the indications for a uni- replacement. Additionally, the report condylar knee replacement include Results stated that the unicondylar knee the following: It is difficult to sort out the results for replacements had more “excellent” • Range of motion of no less than unicondylar knee arthroplasty, as results and a better range of motion 110 degrees with no more than a 5- there are different types of unicondy- compared with the total knee replace- degree flexion deformity. lar knee arthroplasties. Additionally, ment. Registry data, however, such as • A correctable varus on valgus defor- it is difficult to distinguish between the Swedish Knee Replacement Reg- mity of no more than 5 degrees of var- medial side versus lateral side proce- istry, have shown a higher reoperation us or 15 degrees of valgus, with the dures with respect to outcomes. Fur- rate for unicondylar knee replace- correctability of the deformity to be thermore, one has to compare the ment, with the main reason for revi- determined on physical examination. results of a unicondylar knee replace- sion being progression of the arthritis. • An intact anterior cruciate ligament. ment with other options such as a high The results for revision of a unicondy- • Osteoarthritis localized to either the tibial osteotomy and a standard total lar knee replacement to a full knee lateral or medial compartment, keep- knee replacement. Again, various au- replacement are similar to the results ing in mind that the vast majority of thors have reported varying degrees for a primary total knee replacement, unicondylar knee replacements are of success with unicondylar knee and even though unicondylar knee medial. arthroplasty. Recently authors have replacements may not last as long, the • For some fixed-bearing tibial compo- reported 96% survival of the implant outcome of revision is better than that nent designs, a weight limit of 114 kg. at a 10-year follow-up and excellent of a revision of total knee replacement. 444 BC MEDICAL JOURNAL VOL. 52 NO. 9, NOVEMBER 2010 www.bcmj.org
  • Partial knee replacement Complications Indications snapping and instability. Additionally The complications after a unicondylar According to Lonner9 the indications the standard complications for uni- knee replacement are similar to a total and contraindications for a patello- condylar knee arthroplasty can be knee replacement. These complica- femoral arthroplasty are isolated included. There can be ongoing res- tions include inadequate pain relief, patellofemoral osteoarthritis, post- idual anterior knee pain and dys- deep venous thrombosis in 1% to 5% traumatic arthritis, or advanced chon- function. There can be subsidence, of patients, infection in less than 1% dromalacia with eburnation on either polyethylene wear, or loosening. Long- of patients, and unexplained pain or both of the trochlear and patellar term arthritis in the tibiaofemoral about the knee. surfaces. It is contraindicated in pa- joint can also occur. Late complications include loos- ening of a component, subsidence of the component, degeneration of the other compartment resulting in pain, infection, polyethylene wear, and pos- There is renewed interest in partial sible dislocation of the polyethylene component in a mobile-bearing knee knee replacements with recently reported replacement. good long-term outcomes, complications Patellofemoral similar to total knee replacement, and the arthroplasty fall-back option of a conversion to a A patellofemoral replacement ( Figure 2 ) is indicated for the man- total knee replacement. agement of isolated osteoarthritis of the patellofemoral joint. It has to be clear that this form of partial knee replacement is not indicated for pat- ellofemoral pain in the absence of rad- tients with medial or lateral joint line Conclusions iographically proven osteoarthritis. pain or tibiofemoral arthritis or chon- Partial knee replacements may be an dromalacia. It is not felt to be appro- option for a select group of patients. Patient selection priate for inflammatory arthritis or There is renewed interest in partial Patellofemoral arthritis occurs in up crystalline arthropathy. It should be knee replacements with recently re- to 9% of patients over the age of 40 used with extreme caution in a patient ported good long-term outcomes, and 15% of patients over 60.7 Most who has a highly malaligned patello- complications similar to total knee patellofemoral pain or arthritis can be femoral articulation with a high Q replacement, and the fall-back option treated with nonoperative measures angle and is thus at risk for dislocation. of a conversion to a total knee replace- such as activity modification, physi- ment. For the unicondylar knee, it is a cal therapy, analgesics, braces, and/or Results more conservative option with a fast injections. Patellofemoral arthroplas- The component for patellofemoral recovery, good functional outcome, ty may be an option for patellofemoral arthroplasty consists of a metal troch- and is a possible good option to a high arthritis when other treatment modal- lear component and a polyethylene tibial osteotomy or total knee replace- ities have failed. button that replaces the articular sur- ment. The unicondylar knee is most Patients with chondromalacia of face of the patella. Good to excellent commonly done for isolated medial the patella have been treated with results have been reported in short, compartment osteoarthritis and has arthroscopic debridement with limit- mid-term, and medium follow-up. very specific indications. The patello- ed success.8 A patellectomy has been The results are reported as being 80% femoral arthroplasty is possibly indi- used in the past as well. Unfortunate- to 90% good to excellent.9 cated in patients with isolated patello- ly, a patellectomy has its own set of femoral arthritic pain. The limited problems, which include loss of exten- Complications reports on the patellofemoral arthro- sion power and increased risk of arth- The complications after a patello- plasty suggest very good results. ritis in the tibiofemoral compartment. femoral arthroplasty include patellar www.bcmj.org VOL. 52 NO. 9, NOVEMBER 2010 BC MEDICAL JOURNAL 445
  • Partial knee replacement Competing interests None declared. References 1. Kozinn SC, Scott R. Unicondylar knee arthroplasty. J Bone Joint Surg Am 1989; 71:145-150. 2. Pennington DW, Swienckowski JJ, Lutes WB, et al. Unicompartmental knee arthoplasty in patients sixty years of age or younger. J Bone Joint Surg. 2003;85- A:1968-1973. 3. Tabor OB Jr, Tabor OB, Bernard M, et al. Unicompartmental knee arthroplasty: Long-term success in middle-age and obese patients. J Surg Orthop Adv 2005;14:59-63. 4. Christensen NO. Unicompartmental prosthesis for gonarthrosis. A nine-year series of 575 knees from a Swedish hos- pital. Clin Orthop Relat Res 1991; 273:165-169. 5. Berger RA, Meneghini RM, Jacobs JJ, et al. Results of unicompartmental knee arthoplasty at a minimum of ten years follow-up. J Bone Joint Surg Am 2005; 87:999-1006. 6. Newman J, Pydisetty RV, Ackroyd C. Uni- compartmental or total knee replace- ment. The 15-year results of a prospec- tive randomized controlled trial. J Bone Joint Surg Br 2009;91:52-57. 7. Davies AP, Vince AS, Shepstone L, et al. The radiological prevalence of patello- femoral osteoarthritis. Clin Orthop Relat Res 2002;402:206-212. 8. Federico DJ, Reider B. Results of isolat- ed patellar debridement for patello- femoral pain in patients with normal patellar alignment. Am J Sports Med 1997;25:663-669. 9. Lonner JH. Patellofemoral arthroplasty. In: Lotke PA, Lonner JH (eds). Master techniques in orthpaedic surgery: Knee arthroplasty. 3rd ed. Philadelphia, PA: Lip- pincott Williams and Wilkins; 2009:343- 359. 446 BC MEDICAL JOURNAL VOL. 52 NO. 9, NOVEMBER 2010 www.bcmj.org