Salvage of severe knee osteoarthritis: efficacy of tibial condylar valgus osteotomy versus open wedge high tibial osteotomy

Abstract

Introduction: To compare the clinical outcomes and the radiographic features between tibial condylar valgus osteotomy (TCVO) and open wedge high tibial osteotomy (OWHTO). New insight into the indication criteria for TCVO was also clarified for achieving satisfactory results.

Materials and methods: Sixty-three knees with medial-compartment osteoarthritis were retrospectively studied. Thirty-four knees with subluxated lateral joint and depression of the medial tibial plateau underwent TCVO and the rest underwent OWHTO. Among the 63 knees included, 27 knees with a pre-operative femorotibial angle (FTA) ≥ 185° were defined as severe varus (subgroup S, 15 in S_TCVO group and 12 in S_HTO group). Lower limb alignment, intra-, and extra-articular congruency were evaluated according to the radiograph obtained before and 24 months after surgery. The visual analog scale (VAS) score and Hospital for Special Surgery (HSS) score were obtained to assess the clinical results. Opening angle and distance of the opening gap in each group were measured by intra-operative fluoroscopy.

Results: During the 2-year follow-up period, the mean HSS score increased from 70.3 to 81.4 in HTO group and 65.9 to 87.3 in TCVO group (p < 0.05). The mean VAS score decreased from 5.9 to 2.6 and 6.0 to 2.1, respectively (p < 0.01). Pre-operative FTA was restored to 172.9° in HTO group and 171.3° in TCVO group, and percentage of mechanical axis (%MA) was improved to 59.7% and 61.2%, respectively. Joint line convergence angle (JLCA) was slightly restored and medial tibial plateau depression (MTPD) was relatively the same before and after OWHTO, while these parameters improved greatly (from 6.4° to 1.2° and - 8.0° to 5.9°, p < 0.01) in TCVO group. More undercorrected knees were observed in S_HTO group than S_TCVO group (58.3% and 13.3%, p < 0.05). Opening angle and distance of the opening gap were larger in TCVO group (19.1° and 14.0 mm) than those in OWHTO group (9.3° and 10.1 mm, p < 0.05).

Conclusion: Compared to OWHTO, TCVO had priority in treating advanced knee OA with intra-articular deformity. However, TCVO had a limited capacity to correct the varus angle. Besides, TCVO might be suitable for medial-compartment OA with a pre-operative FTA ≥ 185°.

Keywords: Open wedge high tibial osteotomy (OWHTO); Osteoarthritis (OA); Tibial condylar valgus osteotomy (TCVO).

Fig. 1

The ideal correction angle α60 was defined as the angle formed between the first line drawn from the lateral tip of intercondylar eminence to the ankle center, and the second line from the lateral tip of intercondylar eminence to the line passing through the 60% point of %MA, with the length the same as the first line (a). Measurement of lower limb alignment. FTA was defined as the lateral angle between the femoral anatomical shaft axis and tibial anatomical shaft axis. %MA was defined as the point where the mechanical axis intersects the tibial plateau, converted to a percentage from medial edge (0%) to lateral edge (100%) (b). MPTA was defined as the angle between the articular surface of the proximal tibia and the tibial mechanical axis. mLDFA was defined as the angle formed between the articular surface of the distal femur and the mechanical axis of the femur (c)

Fig. 2

Fluoroscopic intra-operative views of a left knee underwent TCVO. a Two guide wires were parallelly inserted at a same horizontal level 3 cm below the joint line, with one positioned at anterior 1/3 and the other at posterior 1/3 of the tibial shaft. Another guide wire was inserted from anteroinferior site of the tibial tubercle and passed towards the tip of the lateral intercondylar eminence. b A spreader was applied to provide valgus force for gradually raising the lateral tibial condyle. c Measurement of opening angle and distance during osteotomy surgery. The distance between the intersections of the osteotomy lines with the medial cortex was defined as opening distance. The angle formed between the margins of osteotomy gap was defined as the opening angle. Application of two prophylactic hollow screws across the intercondylar eminence before fixing the locking plate is essential for protection against fracture under large correction angle

Fig. 3

In cases of severe knee OA with inclined medial tibia plateau (decreased MTPD) and increased joint line convergence angle (JLCA) (a), joint instability caused by the teeter effect still exists after the surgery, no matter how OWHTO adjusts the mechanical axis laterally (b)

Fig. 4

A 58-year-old female underwent tibial condylar valgus osteotomy (TCVO). Pre-operative lateral radiographs of the right (a) and the left (b) knee joints. PPTA was defined as posterior proximal tibial angle (a). Pre-operative standing radiograph of the lower extremities (c). Post-operative lateral radiographs of the right (d) and the left (e) knee joints at 2 years after surgery. Post-operative standing radiograph of the lower extremities at 2 years after surgery (f). She was able to jog and squat after TCVO