Summary

Tibial derotation osteotomy and tibial tuberosity transfer successfully managed patients presenting with anterior knee pain or recurrent patella instability secondary to symptomatic excessive external tibial torsion.

Abstract

Excessive external tibial torsion is a common underestimated cause of recurrent patella subluxation or anterior knee pain.

Aims

The purpose of this study is to evaluate the clinical and radiographic outcome of patients who have undergone tibial derotation osteotomy with simultaneous tibial tuberosity transfer performed by one surgeon (MS).

Methods

Between June 2009 and June 2017, a combined tibial derotation osteotomy and tibial tuberosity transfer was performed in 55 knees in 48 patients (14 males and 34 females) who have fulfilled our preset inclusion/exclusion criteria. The surgical technique involved initial tibial tubercle osteotomy. The proximal tib-fib joint was then dislocated in order to allow rotational correction. The tibial osteotomy was performed 2.5cm below the joint line and the distal tibial was rotated on average 25degrees. The osteotomy was stabilised by either 2 step staples or a fixed angle plate. The tibial tubercle was stabilised following correction of patella height and TTTG distance accordingly with 2 x 4.5mm cortical screws. The mean follow-up period was 4.7 (1-6) years and the mean patient age was 34 years (15- 51 years) at time of surgery. The main presenting complaint was pain, instability or both in 14 (35%), 16 (40%) and 10 (25%) knees respectively. 10/40 (25%) had a previous failed surgery prior to presentation. Functional evaluation was carried out using preoperative and post-operative Oxford Knee Score (OSS) and the Kujala Patellofemoral score. Tibial torsion, femoral version, TTTG and Knee Joint Rotation was measured for all patients.

Results

Patients stayed an average of 2 (± 1.5) days in hospital post surgery. The mean preoperative external tibial torsion was 55°(30-63). The TTTG distance was >20mm in 60% of patients and patella Alta was present in 50%. Significant improvement was found in the OSS and Kujala scores at final follow-up (p< 0.05). One patient suffered a nonunion of the tibial tuberosity osteotomy site which required revision of fixation; one patient had stiffness and required arthroscopic arthrolysis. No further surgical interventions were required except for metalwork removal. Varus mal-union was found in 4/55 (7%) knees at union. Implant removal was done in 19 patients (50%) at a mean of one year post surgery.

Conclusion

Tibial derotation osteotomy and tibial tuberosity transfer successfully manage patients presenting with symptomatic excessive external tibial torsion. To the best of our knowledge, this is the largest series of tibial rotational osteotomies reported. In our study, Patients achieved satisfactory clinical outcomes in terms of pain relief and improved function. The reported re-dislocation rate was 0% in instability patients. Patients should be counselled regarding the high rate of metalware removal. A potential for varus malunion has lead to a change in method of osteotomy fixation to a fixed angled device.