A cruciate-retaining implant can treat both knees of most windswept deformities when performed with calipered kinematically aligned TKA

Abstract

PurposeSurgeons performing total knee arthroplasty (TKA) on the osteoarthritic valgus deformity often use a posterior stabilized (PS) and semi‐constrained implants to substitute for the release of a contracted posterior cruciate ligament (PCL) instead of a cruciate retaining (CR) implant. Calipered kinematic alignment (KA) strives to retain the PCL and use a CR implant. The aim of this study of the windswept deformity was to determine whether the level of implant constraint, outcome scores, and alignment after bilateral calipered KA TKA are different between a pair of knees with a varus and valgus deformity in the same patient. MethodsA review of a prospectively collected database identified all patients with a windswept deformity treated with bilateral TKA (n = 19) out of 2430 consecutive primary TKAs performed between 2014 and 2019. Operative reports determined the level of implant constraint. Patient response to the Forgotten Joint Score (FJS) and Oxford Knee Score (OKS) assessed outcomes at a mean follow‐up of 2.3 years. Postoperative alignment was measured on an A‐P computer tomographic scanogram of the limb. ResultsCR implants were used in 15 of 19 (79%) valgus deformities and 17 of 19 (89%) of varus deformities (n.s.). No knees required a semi‐constrained implant. There was no difference in the median postoperative FJS and OKS (n.s.), and a 1° or less difference in the mean postoperative distal lateral femoral angle (p = 0.005) and proximal medial tibial angle (n.s.) between the paired varus and valgus knee deformity. ConclusionBased on this small series, surgeons that use calipered KA TKA can expect to use CR implants in most patients with windswept deformity and achieve comparable outcome scores and alignment between the paired varus and valgus deformity. Level of evidenceIV

Windswept deformities of the knee are challenging to manage

“…Abnormal force moments around the knee influence progression of pain and OA of the contralateral knee [16]. Although the procedure of TKA is successful with both primary posterior stabilized and cruciate-retaining implants, the surgeon should not hesitate to increase the level of constraint and to use stem extensions if the situation so warrants [21]. Outcomes with single or staged TKA are good and comparable with TKA for bilateral knee OA without WSD [21][22][23][24][25].…”

“…Although the procedure of TKA is successful with both primary posterior stabilized and cruciate-retaining implants, the surgeon should not hesitate to increase the level of constraint and to use stem extensions if the situation so warrants [21]. Outcomes with single or staged TKA are good and comparable with TKA for bilateral knee OA without WSD [21][22][23][24][25]. Skeletal dysplasia, condylar hypoplasia, rheumatoid arthritis, and bony defects present both a defective and deficient bone stock during TKA, which makes the surgery challenging [26].…”

“…Howell et al [21], in a prospective review of 19 patients who underwent bilateral TKA in WSD, looked into the level of implant constraint, outcome scores, and alignment after bilateral, callipered, kinematically aligned TKA and observed that no knees required semiconstrained implant or posterior cruciate ligament release, and a short tibial stem extension was used in only one valgus knee. They did not find any difference in the median postoperative "Forgotten Joint Scores" and "Oxford Knee Scores" between paired varus and valgus knees.…”

Kinematic alignment in total knee arthroplasty

“…Although the component alignment differed from that of MA-TKA, the overall alignment of the limb is similar in both [40]. Because of the wide variability of the angle formed by the anatomical and mechanical axes of the tibia and femur in a healthy population, so called outliers (according to the MA criterion) occur in KA-TKA due to restoration of the native joint alignment [41,42]. KA-TKA had a high 10-year accepted implant survival rate of 98.5% [43,44,45].…”

Reoperations are few and confined to the most valgus phenotypes 4 years after unrestricted calipered kinematically aligned TKA

“…The reviewer selected all patients (N = 198) with normal paired femora and tibiae other than the TKA for the study. A single surgeon (SMH) performed the unrestricted calipered KA TKA through a mid-vastus approach and intraoperatively recorded a series of verification checks using a previously described technique [9]. For the femoral component, the I-E and varus-valgus (V-V) rotations and the A-P and proximal-distal (P-D) positions were set coincident with the native distal and posterior joint lines by adjusting the calipered thicknesses of the distal and posterior femoral resections to within 0 ± 0.5 mm of those of the femoral component condyles after compensating for cartilage wear and kerf of the saw blade.…”