, Volume 470, Issue 1, pp 77-83
Date: 06 Aug 2011

Lateral Unicompartmental Knee Arthroplasty Through a Lateral Parapatellar Approach Has High Early Survivorship

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The literature suggests lateral unicompartmental knee arthroplasties are associated with low revision rates. However, there are fewer reports describing techniques for lateral unicompartmental arthroplasty and whether technique influences ROM and function compared to reports for medial unicompartmental arthroplasty.


We report our indications for lateral unicompartmental arthroplasty, how we perform this procedure, and the subsequent Knee Society scores, ROM, and revision and reoperation rates.

Patients and Methods

From a retrospective review of electronic records from 2004 through 2008, we identified 93 patients who had 100 lateral unicompartmental arthroplasties. Indications were complete lateral bone-on-bone arthrosis with a correctible deformity and maintenance of the medial joint space on varus stress radiographs or isolated lateral disease by diagnostic arthroscopy. Average age was 68 years. Seventy percent of patients were women. At followup, we obtained Knee Society scores and ROM. Minimum followup was 24 months (average, 39 months; range, 24–81 months).


At followup, Knee Society scores averaged 46 for pain, 94 for clinical, and 89 for function, and ROM averaged 124°. Three patients had reoperations: one an open reduction and internal fixation for fracture at 2 years postoperatively, one an arthroscopy for a medial meniscal tear, and one a revision for pain.


Based on our observations, we believe complete cartilage loss laterally and correctible deformity with maintenance of the medial joint on varus stress radiographs are reasonable indications for lateral unicompartmental arthroplasty. We recommend a lateral parapatellar approach can be utilized. The early reoperation and revision rates were low.

Level of Evidence

Level IV, therapeutic study. See the Guidelines for Authors for a complete description of levels of evidence.

One or more authors (KRB, MCK, AVL) have received payments or benefits from a commercial entity (Biomet, Inc, Warsaw, IN) related to this work.
Each author certifies that his institution approved or waived approval for the use of human subjects for this investigation and that all investigations were conducted in conformity with ethical principles of research.
This work was performed at Joint Implant Surgeons, Inc.