58 Primary Constrained Condylar Knee Arthroplasty for the Arthritic Valgus Knee Mark E. Easley, MD*; John N. Insall, MD**; Giles R. Scuderi, MD**; and David D. Bullek, MD † CLINICAL ORTHOPAEDICS AND RELATED RESEARCH Number 380, pp. 58–64 © 2000 Lippincott Williams & Wilkins, Inc. The purpose of the current study was to review results of primary constrained condylar knee arthroplasty in elderly patients with genu val- gum deformity. The hypotheses were: (1) con- straint has no adverse effects in elderly patients; (2) treating deformity with a constrained condy- lar knee prosthesis in lieu of lateral ligament re- lease avoids morbidity, particularly peroneal nerve palsy and flexion instability; and (3) press-fit noncemented stem extensions enhance fixation of the cemented core components and are not prone to loosening. Between 1988 and 1993, 44 consecutive primary Constrained Condylar Knee prostheses were implanted in 37 patients (average age, 72.7 years) with an aver- age valgus angle of 17.6. Indications for the Constrained Condylar Knee implant were: el- derly patients with genu valgum deformity and medial collateral ligament incompetence. Out- come was assessed prospectively using the Hos- pital for Special Surgery and Knee Society scor- ing systems; followup was by independent observer. Clinical and radiographic followup (average, 7.8 years) was available for 28 knees (26 patients). The Hospital for Special Surgery score improved from 52.2 to 89.6 points. The av- erage Knee Society score and functional scores improved from 27.4 and 32.4 points to 95.2 and 67.2 points, respectively. At followup, the aver- age alignment based on anteroposterior radi- ographs obtained with the patient weightbear- ing was 5.3. No radiographic loosening, prosthetic failures, peroneal nerve palsies, or flexion instability occurred. No failures oc- curred in the 11 patients (16 knees) who died be- fore the latest followup. To the authors’ knowl- edge, this is the largest reported series with the longest reported followup of patients with pri- mary Constrained Condylar Knee prostheses. The use of the Constrained Condylar Knee prosthesis for elderly patients with low physical demands with genu valgum resulted in signifi- cant pain relief and improved function. Various techniques have been described to cor- rect a fixed genu valgum deformity. Typically, some type of a lateral soft tissue release with either a posterior cruciate retaining or posterior stabilized prosthesis has been used. 21,27 Occa- sionally, balancing the medial and lateral col- lateral structures requires extensive lengthen- ing of the lateral side to match the medial side. Significant lengthening of the lateral soft tissue structures may result in peroneal nerve palsy postoperatively, 1,21,24,27 flexion instability, 5,10, 12,23,25 or both. An alternative to lateral soft tis- sue release is medial collateral advancement, From the *Duke University Medical Center, Durham, NC; the **Insall-Scott-Kelly Institute, Beth Israel Med- ical Center-Singer Division, New York, NY; and the † Overlook Hospital, Westfield, NJ. Reprint requests to Giles R. Scuderi, MD, 170 East End Avenue, 4 th Floor, New York, NY 10128.