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Lateral Unicompartmental Knee Arthroplasty Through a Medial ApproachStudy with an Average Five-Year Follow-up
Alexander P. Sah, MD1; Richard D. Scott, MD2
1 Department of Orthopaedic Surgery, Massachusetts General Hospital, 55 Fruit Street, GRB 624, Boston, MA 02114-3117. E-mail address: asah07@gmail.com
2 Department of Orthopaedic Surgery, Brigham and Women's Hospital, 75 Fruit Street, Boston, MA 02115
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Disclosure: The authors did not receive any outside funding or grants in support of their research for or preparation of this work. Neither they nor a member of their immediate families received payments or other benefits or a commitment or agreement to provide such benefits from a commercial entity. No commercial entity paid or directed, or agreed to pay or direct, any benefits to any research fund, foundation, division, center, clinical practice, or other charitable or nonprofit organization with which the authors, or a member of their immediate families, are affiliated or associated.
A video supplement to this article will be available from the Video Journal of Orthopaedics. A video clip will be available at the JBJS web site, www.jbjs.org. The Video Journal of Orthopaedics can be contacted at (805) 962-3410, web site: www.vjortho.com.
Investigation performed at the Department of Orthopaedic Surgery, Brigham and Women's Hospital, Boston, Massachusetts

The Journal of Bone and Joint Surgery, Incorporated
J Bone Joint Surg Am, 2007 Sep 01;89(9):1948-1954. doi: 10.2106/JBJS.F.01457
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Background: Unicompartmental knee arthroplasty of the medial compartment has excellent long-term clinical outcomes. Arthritis isolated to the lateral compartment is much less common; subsequently, the clinical outcomes of the treatment of that condition are less frequently reported. Most commonly, the lateral compartment is approached through a lateral arthrotomy. The purpose of this study was to determine the mid-term results of lateral unicondylar replacement through a medial arthrotomy in patients with primary osteoarthritis or posttraumatic arthritis.

Methods: From 1991 to 2004, forty-nine lateral unicompartmental knee arthroplasties were performed in forty-five patients by a single surgeon. One patient was excluded from the study because of a severe underlying neurologic condition. Lateral unicompartmental replacement was performed in thirty-eight knees with primary osteoarthritis and in ten knees with posttraumatic arthritis secondary to a tibial plateau fracture. Retrospective chart reviews and radiographic evaluations were performed, and Knee Society scores were determined.

Results: The average Knee Society knee and function scores improved from 39 and 45 points, respectively, preoperatively to 89 and 80 points at an average of 5.2 years postoperatively. Preoperative alignment averaged 10° of valgus, which was corrected to an average of 6.2° of valgus postoperatively. There were no revisions and no notable soft-tissue complications. The mean postoperative knee and function scores were significantly better for patients with primary osteoarthritis (95 and 86 points, respectively) than they were for those with posttraumatic arthritis (74 and 65 points).

Conclusions: Lateral unicompartmental knee replacement through a medial approach provided durable and reliable short to mid-term results. This approach is safe, effective, and extensile, making it a viable alternative to a lateral approach. The outcomes of lateral unicompartmental replacement in patients with posttraumatic arthritis can be expected to be inferior to those in patients with primary osteoarthritis.

Level of Evidence: Therapeutic Level IV. See Instructions to Authors for a complete description of levels of evidence.

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    Accreditation Statement
    These activities have been planned and implemented in accordance with the Essential Areas and policies of the Accreditation Council for Continuing Medical Education (ACCME) through the joint sponsorship of the American Academy of Orthopaedic Surgeons and The Journal of Bone and Joint Surgery, Inc. The American Academy of Orthopaedic Surgeons is accredited by the ACCME to provide continuing medical education for physicians.
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