The majority of varus knees with deformity of up to 15° have neither a medial contracture nor abnormal lateral laxity when referenced to the individualized neutral axis of the knee. Surgical releases during TKA should be uncommon. Medial contracture when present is influenced by both posterior and medial structures. Lateral laxity is a more consistent feature of the varus knee. The patterns of contracture and laxity are variable with limited correlation to deformity.

Introduction: Balanced soft tissues are important to total knee arthroplasty (TKA) outcomes. Surgical algorithms for balancing are potentially varied in varus and valgus osteoarthritic (OA) knees. While coronal plane varus knee laxity has been documented, no study has objectively defined the medial and lateral laxity of the valgus OA knee. The lower limb was manipulated at the time of TKA using computer navigation, prior to surgical releases, to allow the limb weight-bearing axis to pass through the knee center in maximum extension, 20 and 90 of flexion. The hip-knee-ankle-angle was documented at this position. Coronal plane laxity was then measured in 30 valgus (7.9 + 4.0) knees as medial and lateral displacement from this point and compared to published values for healthy subjects. In maximum knee extension, lateral contracture was present in 26.6% (8/30) of subjects, and abnormally lax medial tissue was present in 46.6% (14/30). Six patterns of medial versus lateral laxity were documented in maximum extension. In maximum knee extension, mean medial laxity was 7.1 (+3.8) compared to 2.7 (+2.7) laterally. In 20 of knee flexion, mean medial laxity was 8.5 (+3.5) compared to 3.0 (+2.6) laterally. In 90 of knee flexion, mean medial laxity was 3.7 (+1.3) and 7.5 (+3.0) laterally. A highly significant difference (p < 0.0001) in mean laxity was demonstrated when comparing medial versus lateral values at each measurement angle and for medial versus medial and lateral versus lateral values for maximum extension and 90 of flexion. The valgus knee at the time of TKA demonstrates significant preoperative mediolateral and flexion-extension imbalance. In maximum extension, medial tissue is significantly laxer whereas in flexion this reverses and the lateral tissue is significantly laxer. We documented more patterns of medial and lateral laxity in maximum extension than advocated in prior subjective grading systems. These findings demonstrate the challenges of valgus OA knee balancing during TKA but provide, for the first time, objective measures for the starting point of this process.

The standard Exeter stem has a length of 150 mm with offsets 37.5 to 56 mm. Shorter stems of lengths 95, 115 and 125 mm with offsets 35.5 mm or less are available for patients with smaller femurs. Concern has been raised regarding the behavior of the smaller implants. This paper analyzed data from the Australian Orthopaedic Association National Joint Replacement Registry comparing survivorship of stems of offset 35.5 mm or less with the standard stems of 37.5 mm offset or greater. At 7 years, there was no significant difference in the cumulative percent revision rate in the short stems (3.4%, 95% CI 2.4-4.8%) compared with the standard length stems (3.5%, 95% CI 3.3-3.8%) despite its use in a greater proportion of potentially more difficult developmental dysplasia of the hip cases.

Leucocyte filtration technology is now beginning to be used in cardiothoracic surgery. The leucocyte depletion of banked homologous blood has been shown to reduce its immunosuppressive effects, along with a range of other benefits. Use of such a blood product appears to be an attractive option during cardiopulmonary bypass (CPB) as this procedure is recognized as causing immune disturbance and long-term immunosuppression. White-cell removal filters also appear to have a novel application in the reduction of neutrophil-mediated damage associated with CPB procedures. A strong database from animal work has been recently supplemented by human data that shows clinical benefits from autologous white-cell removal by filtration.

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