Abstract
Background and purpose — Instability following primary total knee arthroplasty (TKA) is, according to all national registries, one of the major failure mechanisms leading to revision surgery. However, the range of soft-tissue laxity that favors both pain relief and optimal knee function following TKA remains unclear. We reviewed current evidence on the relationship between instrumented knee laxity measured postoperatively and outcome scores following primary TKA.Patients and methods — We conducted a systematic search of PubMed, Embase, and Cochrane databases to identify relevant studies, which were cross-referenced using Web of Science.Results — 14 eligible studies were identified; all were methodologically similar. Both sagittal and coronal laxity measurement were reported; 6 studies reported on measurement in both extension and flexion. In knee extension from 0° to 30° none of 11 studies could establish statistically significant association between laxity and outcome scores. In flexion from 60° to 90° 6 of 9 studies found statistically significant association. Favorable results were reported for posterior cruciate retaining (CR) knees with sagittal laxity between 5 and 10 mm at 75–80° and for knees with medial coronal laxity below 4° in 80–90° of flexion.Interpretation — In order to improve outcome following TKA careful measuring and adjusting of ligament laxity intraoperatively seems important. Future studies using newer outcome scores supplemented by performance-based scores may complement current evidence.
Highlights
Patients and methods — We conducted a systematic search of PubMed, Embase, and Cochrane databases to identify relevant studies, which were cross-referenced using Web of Science
We searched the PubMed, Embase, and Cochrane databases for combinations of search words describing knee arthroplasty, soft tissue laxity, and outcome to identify papers reporting on the relation
This systematic review deals with outcome scores and quantified measurements of soft tissue laxity following primary total knee arthroplasty (TKA)
Summary
Patients and methods — We conducted a systematic search of PubMed, Embase, and Cochrane databases to identify relevant studies, which were cross-referenced using Web of Science. 14 eligible studies were identified; all were methodologically similar Both sagittal and coronal laxity measurement were reported; 6 studies reported on measurement in both extension and flexion. Soft tissue balancing, and choice of implant constraint is dependent on preoperative anatomical conditions, surgical technique, and the experience, preference, and thoroughness of the surgeon. Different surgical techniques to obtain optimal soft tissue balance have been described (Babazadeh et al 2009, Mihalko et al 2009), and numerous tools, such as computer-assisted surgery, trial insert sensors, tensioners, spreaders, spatulas and spacer blocks, have been developed to assist the surgeon quantify intraoperative laxity. Intraoperative evaluation of soft tissue laxity is still challenging and can among other factors be influenced by the position of the patella, muscular tension, and the external load on the knee. In most cases soft-tissue balance is based on subjective assessment, and depends on the individual surgeon’s experience and preferences
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