Lessons learned from selective soft-tissue release for gap balancing in primary total knee arthroplasty: an analysis of 1216 consecutive total knee arthroplasties: AAOS exhibit selection

Abstract

Background: Soft-tissue releases are commonly necessary to achieve symmetrical flexion and extension gaps in primary total knee arthroplasty performed with a measured resection technique. We reviewed the frequency of required releases according to preoperative alignment and the clinical and radiographic results; associations with failure, reoperations, and complications are presented.

Methods: We reviewed 1216 knees that underwent primary total knee arthroplasty from 2004 to 2009; 774 (64%) were in female patients and 442 (36%), in male patients. In the coronal plane, 855 knees had preoperative varus deformity, 123 were neutral, and 238 had valgus deformity. The mean age at the time of the index procedure was 62.7 years (range, twenty-three to ninety-four years), and the mean body mass index was 32.7 kg/m² (range, 17.4 to 87.9 kg/m²). Clinical outcomes included the Knee Society Score (KSS), implant failure, reoperation, and complications. Radiographs were analyzed for component alignment.

Results: The only difference in the total KSS was found at the time of final follow-up between valgus knees with zero releases (total KSS = 178) and those with one or two releases (KSS = 160, p = 0.026). Overall, 407 knees (33.5%) required zero releases, 686 (56.4%) required one or two releases, and 123 (10.1%) required three or more releases. Among varus knees, 37% required zero releases, 55% required one or two releases, and 7.5% required three or more releases. Among neutral knees, 39% required zero releases, 55% required one or two releases, and 5.7% required three or more releases. Only 17% of valgus knees required zero releases whereas 61% required one or two releases and 21.8% required three or more releases. Valgus knees required more releases than neutral or varus knees did (p < 0.001).

Conclusions: Selective soft-tissue release for gap balancing in primary total knee arthroplasty is an effective technique that produced excellent clinical and radiographic results regardless of preoperative alignment. Consistent anatomic coronal-plane alignment and soft-tissue balance could be achieved without bone cut modification by using measured bone resection and selective soft-tissue release.

Fig. 1

Pie chart showing the distribution of varus, valgus, and neutral preoperative alignment.

Fig. 2

Bar graph showing the number of knees that required zero, one or two, and three or more releases.

Fig. 3

Bar graph showing the frequency of soft-tissue releases in all knees.

Fig. 4

Bar graph showing the frequency of soft-tissue releases in varus knees.

Fig. 5

Bar graph showing the frequency of soft-tissue releases in neutral knees.

Fig. 6

Bar graph showing the frequency of soft-tissue releases in valgus knees.

Fig. 7

Scatterplot showing that the number of releases required increased with increased preoperative coronal malalignment (in degrees).

Fig. 8

Histogram showing the postoperative alignment (in degrees) of 1171 knees according to the anatomic axis on a short anteroposterior (AP) radiograph.

Fig. 9

Histogram showing the postoperative alignment of 972 knees according to the mechanical axis (hip-knee-ankle angle) on a long standing radiograph.