Clinical results after distal femoral osteotomies in patients with patellar maltracking
Authors: Frings Jannik , Drenck Tobias C. , Akoto Ralph , Schmeling Arno , Frosch Karl-Heinz 
Published: May 2017

Aims and Objectives:

Few clinical trials analyze the results after distal femoral osteotomies (torsional and axial adjustment) for patellar maltracking with or without patellar instability. The purpose of the presented study is to capture the clinical results as well as the reluxation rate after torsional osteotomy or axial adjustment (Types 3d, 3e and 5 according to Frosch et al.).

Materials and Methods:

Between 2010 and 2015 294 cases of patellar instability and/or maltracking were treated in our hospital, 277 surgically. All patients were classified according to Frosch et al. and treated by the corresponding algorithm. 49 patients received a distal femoral osteotomy. Torsional angle and leg axis were radiologically measured in all patients. We used the common scoring systems and determined the redislocation rate.

Results:

Type 3e and 5 27 cases (18 patients, average 22y) torsional osteotomies were performed. 21 of 27 cases were classified as type 3e (7%), 6 as type 5 (2%). 22 other cases (19 patients) with an average age of 27 years (14-46 years) were classified as type 3d (7,5% of all cases). 17 axial adjustments were performed, 4 isolated MPFL reconstructions and 1 osteotomy of the tibial tubercle. Average femoral antetorsion was 38,6° (±9,3°), die tibial torsion was 35,1° (±11,7°). The average deviation of the leg axis in the frontal plane was 5° (±2,4°) varus (n=9) and 2,8° (±2,9°) valgus (n=14). The mean TT-TG distance was 19,9 mm (±4,9 mm). Torsional osteotomy was combined with MPFL-reconstruction (n=19), tibial tubercle transfer (Ø12,6 mm, n=13) or axial correction (Ø4° varus, Ø6° valgus, n=13), 5 double osteotomies. Torsion was corrected by 13° femoral and 11° tibial on average. After 19 months VAS was 1.2, Kujala 78.8, a Lysholm 79.1, Tegner 4. Only one patient experienced a subluxation after a fall. No redislocation. 3d 7,5% (n=22) showed a mean axial deviation of 6,5° (±2,2°) valgus. Average TT-TG distance was 18,3 mm (±5,8 mm). We performed 15 closed-wedge varus distal femoral osteotomies (Ø6,8°±2,3°), combined with an Elmslie-Trillat (n=14) or Fulkerson procedure (n=1), MPFL reconstruction (n=15) or lateral release (n=1). 4 isolated MPFL reconstructions. One case of a pathological lateral slope with patellar instability was treated by double osteotomy (8° femoral to varus, 4° tibial to valgus). One tibial varisation (5,5°) with MPFL reconstruction and Elmslie-Trillat procedure. Tibial tubercle was medialized by 11 mm ±6,7 mm on average. 22 MPFL reconstructions were done. After average 33 months VAS was 2.3, Kujala 72, Lysholm 79, Tegner 4. No redislocation.

Conclusion:

Torsional and axis correcting osteotomies are suitable techniques to treat patellar instability or maltracking. Clinically the patients’ benefit is substantial. Consideration of additional procedures is crucial to success, a thorough analysis of all causal pathologies is mandatory. The results approve our individual therapy algorithm in the treatment of patellar instability and maltracking caused by torsional deformities or axis deviations.