One-stage total knee arthroplasty for patients with osteoarthritis of the knee and extra-articular deformity

Abstract

Purpose: The purpose of this paper is to review our experience and study the feasibility and clinical results of one-stage total knee arthroplasty (TKA) for patients with osteoarthritis of the knee with extra-articular deformity.

Methods: Nine patients with osteoarthritis of the knee associated with extra-articular deformity underwent one-stage TKA from June 2006 to April 2010. There were two men and seven women, with an average age of 51 years (range 34-69 years); four of them had tibial deformities and five had femoral deformities. Eight of the cases resulted from malunion after fracture healing and one from femoral recurvatum. Six of the cases had uniplanar and three had biplanar deformities. The average angles of the femoral deformities were 13.3° in the coronal plane (8-22) and 11.3° in the sagittal plane (6-15); one femur had 10° external rotational deformity. Tibial deformity of 16° in the coronal plane (11-22) was noted, and one had sagittal plane deformity of 21°.

Results: All patients were followed for an average of 29 months. The average Hospital for Special Surgery (HSS) knee score improved from 18.7 points pre-operatively to 89.8 points at the time of last follow-up; the range of knee motion improved from 46.7° preoperatively to 100.6° postoperatively. The average angle of mechanical axis deviation was restored from 11.8° preoperatively to 1° postoperatively. One of the patients had unsatisfactory clinical results due to delayed union at the osteotomy site. No complications such as infection, deep vein thrombosis, ligament instability, low level or subluxed/dislocated patella or component loosening were observed. One-stage TKA with intra-articular correction of the extra-articular deformity was performed in seven patients, included proper planning, appropriate bone cuts to restore alignment and the necessary soft tissue releases to balance the knee in flexion and extension. Two patients underwent simultaneous extra-articular correctional osteotomy and TKA because the deformity was so large. Five knees that had good collateral ligamentous stability and balance received a posterior stabilised prosthesis; four knees that had ligamentous instability received a constrained condylar knee (CCK) prosthesis.

Conclusions: One-stage TKA is a technically difficult but effective treatment for patients with osteoarthritis of the knee and extra-articular deformity. If feasible we recommend TKA with intra-articular bone resection and soft tissue balancing.

Fig. 1

A 64-year-old woman who had had arthritis with extra-articular deformity. a Preoperative standing full-length radiograph showing 15° valgus deformity caused by malunited proximal tibial fracture, which resulted in a mechanical axis deviation of 11°. b Postoperative radiograph made 6 months after one-stage TKA with intra-articular bone resection and soft tissue balancing, showing restoration of the mechanical axis

Fig. 2

To recreate the mechanical axis of the lower extremity, the orientation of the proximal tibial bone resection must be perpendicular to the line across the centre of the knee and ankle joint (red line), not to the distal tibial shaft (black line). However, a residual amount of ankle malorientation will still be present because the tibial shaft deformity remains

Fig. 3

A 38-year-old woman who had had arthritis with extra-articular deformity. a Preoperative radiograph showing 15° sagittal deformity caused by malunited distal femur fracture. b Postoperative lateral radiograph made 2 years after one-stage TKA with intra-articular bone resection and soft tissue balancing, showing excellent alignment of the femoral component and no radiolucency about the component

Fig. 4

A 34-year-old woman who had had arthritis with extra-articular deformity. a, b Pre-operative radiographs showing ankylosis and 21° sagittal deformity caused by dysplasia of the left proximal tibia. c, d Postoperative radiographs made 1 month after TKA with simultaneous extra-articular correctional osteotomy, showing restoration of the mechanical axis and excellent alignment of the component