ROTATIONAL OSTEOTOMY OF THE PROXIMAL TIBIA FOR MAL-TRACKING/ DISLOCATION OF THE PATELLA.

Abstract

Purpose: Mal-tracking or dislocation of the patella is often the result of abnormal anatomy. Understanding the abnormal anatomy will clarify the treatment options available. The common anatomical causes of dislocation range from the valgus knee with an elevated ‘Q’ angle to patella alta with a hypo-plastic trochlea, to external tibial torsion, resulting in an excessive ‘Q’ angle. External tibial torsion results in symptoms ranging from patello-femoral pain to subluxation or dislocation. Many patients are asymptomatic prior to an injury. The decision to correct the underlying anatomical abnormality is often a difficult one.

Methods: A retrospective study of 232 rotational HTO’s in 221 patients operated on between 1990 and 2003 was conducted. The pre-operative degree of external tibial torsion and ‘Q’ angle was noted as well as the degree of rotation. The extent, if any patello-femoral pathology, was noted. Assessment was carried out using the HSS scoring system and Lysholm score.|Notation was made of prior surgery to the knee ranging from arthroscopy to patella tendon transfer to patellectomy.

Results: Of the 232 cases 80% were good to excellent with resolution of patello-femoral pain and instability. 10% had residual pain but no instability and 20 cases had to proceed to total knee replacement.|The best results were seen in cases with pain and instability but minimal patello-femoral pathology. Even cases with end-stage patello-femoral osteoarthritis were improved by maximizing the function of the extensor mechanism.

Conclusions: Rotational osteotomy of the proximal tibia for symptoms of patello-femoral instability secondary to significant external tibia torsion provided much better results than isolated patella tendon transfer.