Change in Limb Length After Total Knee Arthroplasty

Abstract

The clinical outcome of total knee arthroplasty (TKA) remains suboptimal in some patients. One of the factors that might hinder improved functionality may be postoperative limb length discrepancy due to increase in limb length of the operative limb. The objective of this cross-sectional prospective study was to examine the extent to which limb length change occurs after TKA and to compare the change in limb length to the degree of valgus or varus joint position preoperatively. The role of body mass index and Kellgren-Lawrence grade in limb length change was also assessed. The data of 137 TKAs were analyzed and separated into categories to compare change in limb length pre- versus postoperatively. In all, 59.1% of patients experienced an increase in limb length with an average increase of 0.438 cm, but overall, there was no statistically significant difference in limb length pre- versus postoperatively (P value 0.598). Similar trends were seen within all other groups. It is the conclusion of this study that limb lengthening after TKA does not frequently occur to a statistically significant extent, regardless of preoperative joint state.

Limb Lengthening after Primary Total Knee Arthroplasty: Customized Patient-Specific Instrumentation Does Not Affect Expected Limb Lengthening

“…All TKAs were grouped three times discretely for analysis: grouping one consisted of varus and valgus groups, grouping two consisted of “customized” and “conventional” groups, and grouping three consisted of “severe varus,” “severe valgus,” and “moderate malalignment” groups. Values greater than 10° in either varus or valgus qualified into “severe varus” or “severe valgus,” respectively, with the third group of “moderate malalignment” to capture the remaining knees in accordance with previously published studies [ 2 , 8 ]. The mean limb lengthening and frequency of limb lengthening overall as well as the mean preoperative and postoperative alignment in each group were determined.…”

“…This can occur after TKA due to limb lengthening of the operative leg [ 2 , 6 , 7 ]. Studies from 2012 and 2015 have shown that limb lengthening occurs frequently after TKA, though the extent of the lengthening is unclear [ 2 , 8 ]. Additionally, recent advances in total joint technology may permit greater control over limb lengthening to allow for more precise outcomes.…”

Limb length discrepancy after total knee arthroplasty: A systematic review and meta-analysis

“…Chang et al [ 13 ] reported the association between greater LLD with smaller BMI in their series of 466 patients at one-year follow-up[ 13 ]. All studies reported a greater increase in limb length following valgus deformity than varus[ 12 , 14 ]. The pooled analysis of two studies reporting the limb length variation following TKA observed limb lengthening of 7.06 mm in valgus deformity vs 4.42 in varus deformity ( P < 0.05)[ 12 , 14 ].…”

“…All studies reported a greater increase in limb length following valgus deformity than varus[ 12 , 14 ]. The pooled analysis of two studies reporting the limb length variation following TKA observed limb lengthening of 7.06 mm in valgus deformity vs 4.42 in varus deformity ( P < 0.05)[ 12 , 14 ]. The LLD (MD -2.69 mm; 95%CI: -5.11, -0.27) was significantly less in varus knee compared to the valgus knee.…”

“…There are limited studies in literature till date evaluating LLD after TKA[ 11 - 18 ]. While few studies reported LLD as a common occurrence after TKA[ 11 - 14 ], others reported that radiographic LLD is uncommon[ 15 - 17 ]. Recently, few researchers have reported radiographic LLD of ≥ 10 mm as a clinically relevant change[ 16 , 17 ].…”