High tibial osteotomy increases patellofemoral pressure if adverted proximal, while open-wedge HTO with distal biplanar osteotomy discharges the patellofemoral joint: different open-wedge high tibial osteotomies compared to an extra-articular unloading device

Abstract

Purpose Valgus high tibial osteotomy (HTO) and a recently introduced extra‐articular absorber have been shown to efficiently unload the medial compartment of the knee. However, only little is known about the influence of these treatment modalities on biomechanics of the patellofemoral joint. The purpose of this study was to investigate and compare the impact of different HTO techniques and implantation of an extra‐articular absorber on patellofemoral contact forces. Methods Fourteen fresh frozen cadaveric knees were tested in a specially designed knee simulator that allowed simulation of isokinetic flexion–extension motions under physiological loading. Mean contact pressure (ACP) and peak contact pressure (PCP) of the patellofemoral joint was measured continuously between 0° and 120° of knee flexion using a pressure sensitive film in the following conditions: native, after biplanar medial open‐wedge HTO with 5° and 10° correction angle performing an ascending frontal osteotomy of the tibial tuberosity, and after implantation of an extra‐articular absorber system (KineSpring®). Including a second testing cycle with a biplanar medial open‐wedge HTO with 5° and 10° correction angle performing descending frontal osteotomy of the tibial tuberosity. Values after each procedure were compared to the corresponding values of the native knee. Results Biplanar proximal osteotomy leaded to a significant increase of retropatellar compartment area contact pressure compared to the first untreated test cycle (Δ 0.04 ± 0.01 MPa, p = 0.04). Similar results were observed measuring peak contact pressure (Δ 1.41 ± 0.15 MPa, p = 0.03). With greater correction angle 5°, respectively, 10° peak and contact pressure increased accordingly. In contrast, the biplanar distal osteotomy group showed significant decrease of pressure values (p = 0.004). The extracapsular, extra‐articular absorber had no significant influence on pressure levels in the patellofemoral joint. Conclusion HTO with a proximal biplanar osteotomy of the tuberositas tibia significantly increased patellofemoral pressure conditions depending on the correction angle. In contrast a distally directed biplanar osteotomy diminished these effects while implantation of an extracapsular, extra‐articular absorber had no influence on the patellofemoral compartment at all. Consequently, patients with varus alignment with additional retropatellar chondropathia should be treated with a distally adverted osteotomy to avoid further undesirable pressure elevation in the patellofemoral joint.

Effect of Medial Open-Wedge High Tibial Osteotomy on the Patellofemoral Joint According to Postoperative Realignment

“…Previous studies noted that valgus alignment could lead to a higher incidence of pathology in the patellofemoral joint. 16,37 The postoperatively realigned mechanical axis usually falls on the preoperatively planned target point in most patients who undergo MOWHTO. However, under-or overcorrection of the mechanical axis occurs in some patients for various reasons, even after meticulous planning.…”

Increased patellar bone tracer uptake in preoperative SPECT/CT before medial opening high tibial osteotomy correlates with inferior clinical outcome

“…The most important findings of this study were the following three: Firstly, preoperative elevated BTU values in the patellar region correlated significantly with a worse clinical outcome. It was previously shown that MOWHTO leads to an increase of the contact pressure in the patellofemoral joint (PFJ) [15,19,20,25,37,39]. Kim et al [19] suggested that the increased loading of the PFJ may be the cause of postoperative pain and be associated with the development and progression of OA in the PFJ.…”

Diz çevresi osteotomilerinin biyomekanik prensipleri

“…[1,19] Dolayısıyla bu osteotomi tekniği PF kondromalazisi olan hastalarda da tercih edilebilir. [20]…”