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

Table 2 Details of the patients, intervention and follow up duration as mentioned in the studies

Ref.	Inclusion/exclusion criteria	No of knees (UL, BL)	Study design	Age in years ± SD (range)	Sex (M:F)	BMI (Kg/m2)	Intervention (TKA)	Follow up
Vaidya et al[11], 2010 (level IV)	BL OA knee with varus deformity, operated for unilateral or bilateral TKA with minimum 6 mo follow up (n = 54 pts)	30 UL	Cohort retrospective	64 (48-80)	7:23	-	Mid-vastus approach; PFC sigma RP-F Highflex (56), PFC Sigma RP (26), IB II Zimmer (2); Patella replaced	Minimum 6 mo
		30 BL (six pts underwent stage wise TKA, included in both groups)	Cohort retrospective	65.8 (54-83)	6:24	-		Minimum 6 mo
Lang et al[12], 2012 (level III)	BL OA knee (both varus and valgus) without significant extraarticular deformity (n = 102 pts)	102 (54 UL, 47 BL)	Cohort retrospective	70.3 ± 9.9	35:67	30.0 ± 6.4	Medial parapatellar approach, principles of flexion/extension gap balancing85 CR and 17 PS	6 wk
Chang et al[13], 2013 (level III)	Inclusion: TKA for primary OA knee with one year follow up. Exclusion: Pts with previous surgery on the ipsilateral limb, spine surgery, neurological disorders, cancer, death due to diseases unrelated to TKA, periprosthetic infection, or another condition capable of affecting the result of this study, such as depression, dementia, or problems of the contralateral knee were excluded (n = 466 pts)	761 knees (171 UL, 295 BL, 466 patients)	Cohort Retrospective study (prospectively collected data)	67.9 ± 5.9 (49–84)	26:440	27.1 ± 3.4	Medial parapatellar approach, patella replaced	1 yr
Tipton et al[14], 2015 (level III)	Inclusion: Primary TKA with availability of both preoperative and postoperative standing full-length radiographs for measurement. Exclusion: Patients with gross bony deformities or poor quality radiographs were excluded (n = 137)	137 UL	Cross sectional Prospective study	68 ± 10	40:82	30 ± 5.0	Medial parapatellar approach, minimal bone resection with thinnest poly-insert	Postoperative setting
Kim et al[4], 20151 (level IV)	Inclusion: Primary computer-assisted TKA in OA knee with varus deformity. Exclusion: Varus > 20°, hip pathology, osteotomy in the affected limb, severe bony defects, severe osteoporosis, flexion contracture > 30°, BMI > 30 kg/m2, and spine deformity with pelvic tilt	148 (≤ 15 mm LLD in 81 knees, 55 pts; > 15 mm LLD in 67 knees, 52 pts)	Cohort retrospective	≤ 15 mm: 69.1 ± 6.7; > 15 mm: 70.1 ± 8.4	15:133	≤ 15 mm: 26.3 ± 3.2; > 15 mm: 27.1 ± 3.6	Mid-vastus approach, Orthopilot navigation system. PS implant. No patella resurfacing	Minimum 2 yr
Goldstein et al[15], 2016 (level III)	Inclusion: Primary TKA for unilateral osteoarthritis between 18-90 yr of age. Exclusion: Pts with allergy or intolerance to the study materials, previous surgeries on the ipsilateral or contralateral joints or limbs likely to affect the outcome, substance abuse or dependence within the past 6 mo (n = 71)	71 UL	Cross sectional prospective study	65 ± 8.4 (47-89)	27:44	35.1 ± 9.9 (20.2-74.8)	Medial parapatellar or midvastus approach	1 yr
Chinnappa et al[16], 2017 (level II)	Inclusion: Primary unilateral TKA without extraarticular deformity (n = 91). Exclusion: Patients with known leg length inequality due to other causes (radiographic leg lengthening post THA > 5 mm and longstanding leg length inequality > 5 yr requiring orthotics) were excluded.	91 UL	Cohort. Prospective study	70.2 ± 8.9 (50-89)	34:57	29.4 ± 5.0 (17.5–48.6)	Medial parapatellar approach, aim to restore neutral HKA axis. PS implant. Bone resection using Jig or computer navigation	Radiographic measurement on second postoperative day, functional outcome at 6 mo
Hinarejos et al[17], 2020 (level II)	Inclusion: Unilateral primary TKA. Exclusion: Pts with previous fractures of the lower limbs, patients with surgeries or diseases affecting any of the hips or ankles, preoperative or postoperative flexion contracture > 5°, poor quality radiographs, patients without postoperative KSS evaluation (n = 460)	460 UL	Cohort. Prospective study	71 ± 8.4	128:332	31.3 ± 4.9	Medial parapatellar approach; intramedullary guide for femur and extramedullary jig for tibia, minimal bone resection with thinnest insert. CR in 30.4%, PS in 69.6%. Patella replaced	At 6 mo, radiographic evaluation; at 1 yr, functional evaluation

¹The study by Kim et al[4], 2015 divided the study group into LLD ≤ 15 mm vs > 15 mm and then compared.

OA: Osteoarthritis; UL: Unilateral; BL: Bilateral; M: Male; F: Female; BMI: Body mass index; LLD: Limb length discrepancy; CR: Cruciate retaining; PS: Posterior stabilized; KSS: Knee society score; TKA: Total knee arthroplasty; HKA: Hip—knee—ankle angle.