Patellofemoral cartilage defects are acceptable in patients undergoing high tibial osteotomy for medial osteoarthritis of the knee

Abstract

Background: Patients suffering cartilage defects of the medial compartment with underlying varus deformity do benefit from high tibial osteotomy (HTO) even in the long term. Nonetheless, kinematic and geometric changes especially in the patellofemoral joint have been described. Purpose of the present study was to evaluate the influence of patellofemoral cartilage defects detected during the diagnostic arthroscopy and their influence on HTO's postoperative outcome.

Methods: Ninety patients with a mean follow-up of 10.08 ± 2.33 years after surgery were included. Patients were divided into four groups according to their cartilage status in the patellofemoral joint (A = no defects, B = isolated lesions of the patella, C = isolated lesions of the trochlea, D = kissing lesions). Functional outcome was evaluated before surgery and about ten years thereafter by relying on the IKDC, Lysholm, and KOOS scores. Radiological parameters were assessed pre- and six weeks postoperatively.

Results: In groups A to D, the HTO led to significant patellar distalisation in the sagittal view, with the mean indices remaining at or above the limit to a patella baja. All patients in all groups profited significantly from HTO (higher Lysholm score, lower VAS p < 0.001), patients in group D had the lowest outcome scores. Patella height negatively influenced outcome scores in group C (Blackburne-Peel-Index-VAS p = 0.033) and D (Caton-Deschamps-Index-Tegner p = 0.018), a larger valgus correction was associated with lower outcome scores in group D (Lysholm p = 0.044, KOOSpain 0.028, KOOSQOL p = 0.004).

Conclusion: Long-term results of HTO for varus medial compartment osteoarthritis remain good to excellent even in the presence of patellofemoral defects. Overcorrection should be avoided. Distal biplanar HTO should be considered for patients presenting trochlear or kissing lesions of the patellofemoral joint.

Trial registration: DRKS00015733 in the German Registry of Clinical Studies.

Keywords: Cartilage defects; High tibial osteotomy; Knee; Patella; Varus deformity.

Fig. 1

Patient Flow Chart. Data on patients excluded from the study who had refused to participate, died, or were not reachable. Patients with HTO and ACI were excluded for this analysis

Fig. 2

Pre- to postoperative CDI and BPI values changed significantly with a postoperative CDI of 0.88 ± 0.17 (95% CI 0.85 – 0.92)* and postoperative BPI of 0.80 ± 0.16 (95% CI 0.77 – 0.84)*. The ISI did not change significantly

Fig. 3

Patella distalisation in groups A – D. Significant changes from pre- to postoperative values were observed in group A (CDI p = 0.006), B (CDI p = 0.001, BPI p = 0.006), C (CDI p < 0.001, BPI p < 0.001) and D (CDI p < 0.001, BPI p = 0.001)

Fig. 4

Groups A to D patients rise in Lysholm Scores and lower VAS pain levels. Sports and work activity levels fell significantly (Tegner pre- to postOP Groups A – D p < 0.001)