Extra-articular deformities in arthritic knees-a grueling challenge for arthroplasty surgeons: An evidence-based update

Abstract

Critical to the success of a total knee arthroplasty (TKA) is the anatomical alignment. This may appear as a challenge in an extra-articular deformity (EAD) that may be inherent in certain people or result from fracture malunion, congenital disorders, nutritional, metabolic and infective causes. This appraisal aimed at providing the reader with an up-todate overview of the research carried out on, and existent evidence of EAD correction while planning a TKA. We reviewed the current English literature on TKA in extra-articular knee deformities. Among the published data, a common initial approach of mandatory clinical and radiological assessment emerges as an obligatory step while handling cases with EAD. While several methods of managing the deformity and arthritis have been described, a broad division into intra-articular and extra-articular means can be deciphered. The relatively old-school, yet reliable thought process of extra-articular correction allows an all-inclusive restoration of alignment with the inherent complications related to the necessary osteotomy. A cohort of younger and more venturesome surgeons seem inclined towards performing navigated, intra-articular correction for mild to moderate and sometimes, severe deformities. The crux of the matter lies is obtaining a well-balanced knee without violating the all-important cruciates. Restoring the patient's ambulatory status seems sooner with the intra-articular methods which are also more precise in determining the axes and while removing minimum bone. Greatest satisfaction is accomplished in those with less grotesque, rotationallyaligned knees while meticulously balancing soft-tissues and encouraging earlier weightbearing.

Keywords: complex total knee replacement; extra-articular deformities; intra-articular versus extra-articular correction; navigated total knee arthroplasty.

Figure 1.

A) Normal axes of the lower limbs, B) mechanical axes in varus and valgus deformities (Courtesy: Sunshine Hospitals, India).

Figure 2.

Defining an extra-articular deformity: a deformity originating beyond the collateral ligaments.

Figure 3.

A,B) Tibial extra-articular deformity planned for extra-articular correction.

Figure 4.

Tibial extra-articular deformity corrected by extra-articular correction.

Figure 5.

A, B) Femoral extra-articular deformity planned for intra-articular correction.

Figure 6.

A, B) Femoral extra-articular deformity corrected by intra-articular correction.