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the posterior aspect of joint is removed. Excess posterior cement should be brought into view for removal (Fig. 14). If the Z retractor is placed back in the joint, it should always be checked first to make sure that it does not have any excess cement. The trial polyethylene component is removed when the cement hardens, and the real polyethylene is inserted after checking the gaps (Fig. 15). We advise avoiding making the knee too tight. The MCL is checked in extension and flexion to ensure appropriate laxity. The wound should be copiously irrigated before closure of the incision in the surgeon’s preferred standard fashion; our preference is a subcuticular monocryl (Fig. 16). COMPLICATIONS AND OUTCOMES Please see “Outcomes and Complications of Unicondylar Arthroplasty” by Della Valle et al, elsewhere in this issue for detailed outcomes and complications. Long-term outcomes of UKA performed with IM instrumentation are good. Berger and colleagues reported 98% survivorship at 10 years and 95.7% at 13 years when conversion to TKA was used as the end point in 62 consecutive patients. When aspetic loosening was used as an end point, survivorship increased to 100% at 13 years; 80% of patients reported excellent satisfaction, 12% reported good satisfaction, and 8% reported fair satisfaction. The 2 failures were because of progression of symptomatic arthritis in other compartments, albeit at a slow progression rate of 7 and 11 years. Patients with UKA outperform their peers with TKA on reported symptoms, activities of daily living, and sport and recreation.47,48 Patients with UKA show greater knee ROM and report less difficulty with activities that involve bending their knee.48,49 Body mass index (BMI, calculated as weight in kilograms divided by the square of height in meters) does not adversely affect outcomes50 and persons with BMI greater than 35 continue to show functional improvement for at least 2 years after surgery.51 In a recent review of our series, 52 of 56 patients (93%) who participated in sports preoperatively and underwent UKA returned to sports within 6 months after UKA. The 3 patients who did not resume sports postoperatively did not resume sports for reasons unrelated to their knee. All patients who participated in tennis (N 5 14) and skiing (N 5 23) preoperatively resumed after UKA without complication. Fig. 14. The femoral and tibial components are cemented in place and any excessive cement outside the components or under the engaging locking mechanism is safely removed. UKA: Intramedullary Technique 99 POSTOPERATIVE PROTOCOL AND REHABILITATION ROM exercises are initiated immediately postoperatively in the postanesthesia care unit, and a multimodal pain control regimen is routinely used, including nonsteroidal antiinflammatory drugs and 1-time intravenous steroid intraoperatively to control swelling.52 A Hemovac drain is also used and sewn in the knee. We have found that the number 1 complication in our patients is too much activity too fast too soon with hematoma collection. For this reason, a drain is left in for several days, and we have had no infections. A CPM device and extensive icing are used to return our patients to activities in an accelerated fashion. The drain is taken out in the office and ambulation is partial weight bearing with crutches or a walker for the octogenarians. Deep vein thrombosis prophylaxis is based on risk stratification in accordance with the recommendations from the American Academy of Orthopaedic Surgeons.53 We prefer Coumadin for 6 weeks with thigh-high compression stockings. A formal outpatient rehabilitation program is prescribed including wall slides and stationary bike riding without tension and the seat placed high to avoid excessive flexion starting on day 1. Emphasis is placed on ROM, restoration of normal mechanics, and strengthening of the core, hip, and quadriceps, which has been shown to decrease rates of anterior knee pain and improve outcomes.54–56 Strength Fig. 15. The real polyethylene insert is snapped into place with an audible sound. Fig. 16. Final UKA with real polyethylene liner. (A) Knee in full flexion. (B) Knee in full extension. 100 Dunn et al training is not initiated until 6 weeks postoperatively. Patients are permitted to return to their desired activities without restrictions after the completion of their physical therapy program. We allow patients to return to golf (riding in a cart) at 8 to 12 weeks, depending on swelling. Singles tennis and downhill skiing are permitted at 6 months. SUMMARY UKA is a reliable method of alleviating pain and restoring function in patients with knee arthritis with the appropriate indications and meticulous surgical technique. Use of IM instrumentation on the femur provides a similar operative experience to TKA, allowing most surgeons the comfort of a procedure known well to them. Preoperative goal setting and postoperative rehabilitation involving core, hip, and quadriceps strengthening are nonsurgical adjuncts, which enhance outcomes and patient satisfaction in this already successful procedure. troduction Knee osteoarthritis (OA) represents a significant public health challenge internationally. The increasing burden of knee OA worldwide is evident from the results of the Global Burden of Disease Study1 . This landmark study highlighted a major shift in the global
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