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

Table 3 Limb lengthening/limb length discrepancy after total knee arthroplasty surgery

Ref.	Deformity (degree)			Pre-op LLD (mm)	Postop LLD (mm)	% of patients with limb lengthening/LLD	Limb lengthening (mm)	% of patients with perceived postop LLD	Factor affecting radiographic LLD/remarks
	Preop (o)	Postop (o)	Change in alignment (o)
Vaidya et al[11], 2010	-	-		-	15.3 ± 2.88	83.3 (≥ 10 mm in all)		8 (26.7)	LLD is more common after unilateral TKA than bilateral. LLD of ≥ 2 cm is perceived by patient after unilateral TKA. LLD affects the functional outcome after UL TKA in BL OA knee with varus deformity
	-	-		-	5 ± 2.01	46.66 (≥ 10 mm in all)		0
Lang et al[12], 2012	2.5	1	1.5	-	2 (95%CI: 0.5-3.5)	83.3%	6.3 ± 6.85 (range -11-24)	-	Limb lengthening is frequent after TKA and is almost similar to that of nonoperative limb. Limb lengthening had no relationship with age (P = 0.864), sex (P = 0.514), BMI (P = 0.548), or constraint type (P = 0.849), contralateral OA knee severity. LLD in bilateral TKA is minimal but it is significantly different in unilateral TKA
Chang et al[13], 2013	11.9 ± 5.5º (37o to -9º)	1.5 ± 2.7 (11o to -6o)	10.4	6 ± 5	5 ± 4	43.9% limb lengthening by ≥ 10 mm, 3.4% limb shortening of ≥ 10 mm	9 ± 1.1	-	Greater LL increase was correlated with a greater preoperative HKA angle and smaller BMI. Preoperative flexion contracture, postoperative flexion contracture and postoperative HKA have no correlation to LL. Limb length, height, and weight increased, BMI remained unchanged, and LLD decreased 1 year after TKA. The bilateral group had a greater height increase and lower rate of LLD
Tipton et al[14], 2015	4.16	2.76	1.40	-	-	59.1%	4.28 ± 1.11, 59% reported increase in limb length by 4.38 mm		There was no correlation BMI with limb length. Limb lengthening after TKA does not frequently occur to a statistically significant extent, regardless of preoperative joint state
Goldstein et al[15], 2016	-	-	-	-	-	-	-	10%	Perceived LLD is common in patients undergoing TKA and it decreases after surgery. About 10% of patients perceive a LLD after surgery and it usually resolves with time. Age, BMI, Preoperative and postoperative mechanical axis and preoperative perceived LLD has no correlation with postoperative perceived LLD
Chinnappa et al[16], 2017	-3.1	0.8	3.9	-3.0 ± 8.0	0.4 ± 10	77% (≥ 10 mm in 11%)	3.5 ± 8.4 (77% lengthened: Mean 6.7 ± 4.9 mm; 23% shortened: Mean -7.4 ± 8.5)	14%	Radiographic LLD is uncommon after TKA. It has no correlation with age, sex, BMI, polyethylene insert thickness, pre-operative FFD, post-operative FFD, contralateral knee OA, or arthroplasty, severity of pre-operative angular deformity or degree of angular correction. Post-operative radiographic LLD is associated with increased preoperative LLD (P < 0.001). Perceived post-operative LLD was associated with female gender (P = 0.02), decreased satisfaction (18% vs 84%, P < 0.001) and poorer functional score
Hinarejos et al[17], 2020	5.5 ± 7.7	3.7 ± 3.8	1.8	-1.1 ± 6.4	0.8 ± 6.1	60% (≥ 10 mm in 8.26%)	1.9 ± 8.84		Increased LLD has no correlation with age, gender, BMI, HKA angles or with preoperative knee function. However HKA angle changes correlate with LLD. Significant LLD is not frequent after TKA, but the functional results of the surgery can be suboptimal when it is present

Limb length measurement: Vaidya et al[11], 2010-clinical method of measurement using measuring tape was used for limb length measurement in supine position; remaining. OA: Osteoarthritis; BMI: Body mass index; LLD: Limb length discrepancy; TKA: Total knee arthroplasty; HKA: Hip—knee—ankle angle.