The semitendinosus tenodesis for recurrent dislocation of the patella.

Dislocation of the patella may be congenital, it may be due to injury, or it may be simply habitual or recurrent, with some basic defect in the anatomy of the knee region. This review concerns the recurrent type, occurring either spontaneously or after minor injury. Patients with recurrent patellar dislocations may have any ofthe following abnormalities: I ) a high-riding patella with an elongated patellar tendon ; 2) genu recurvatum associated with generalised ligamentous laxity: 3) hypoplasia of the lateral condyle; 4) medial angulation of the line of pull of the quadriceps mechanism because of genu valgum; 5) contracture lateral to the patella or of the vastus lateralis (Williams 1968). At present the most widely used operation for recurrent dislocation of the patella is transplantation of the tibial tubercle downwards and medially, as described by Roux in I 888 and popularised by Hauser in 1938. This procedure is usually successful in adults, but it does entail considerable risks to the rapidly growing child : for example, premature closure of the anterior aspect of the upper tibial epiphysis with a resulting recurvatum deformity; distal migration of the tibial tubercle; and the formation of traction spurs (Macnab 1952, Harrison 1955). Both these authors recommend avoiding operation onthe tibialtubercle of a child under fourteen years; Mi i h d i cat (1950) described over 100 techniques for the treatment of recurrent dislocation of the patella. Heywood (1961) stated that its treatment in children was unsatisfactory because of risks involved in transplantation of the tibial tubercle and also the high failure rate of soft-tissue procedures in the series that he reviewed. McFarland (1948) advocated patellectomy as the primary treatment in all cases of recurrent dislocation of the patella. Macnab (1952) reserved patellectomy for patients found at operation to have degenerative changes in the articular cartilage of the patella. Several authors (Scott 1949, Smillie 1951, McKeever 1954) have emphasised that a knee without its patella is partly disabled. Both Smillie (1951) and Harrison (1955) suggested that degeneration of the joint could be arrested or even reversed if the correct relationship of the patella to the femoral condyles was re-established. Many soft-tissue procedures have been devised in attempts to prevent both the dislocation and the onset of arthritic changes. The disappointing results of many of these procedures have led to most of them being abandoned. Bowker and Thompson (1964) reported a high failure rate from the Goldthwait procedure, the Ober fascial strip procedure and capsulorrhaphy. In view of the hazards involved in transplantation of the tibial tubercle, the disability resulting from patellectomy and the high failure rate of many of the soft-tissue procedures, an operation was sought that would fulfil the desiderata suggested by Hauser (1938). According to him the operation should prevent recurrent dislocation, provide the patient with a feeling of absolute security in the knee, re-establish functional capacity, not damage the appearance of the knee, have minimal risk to the patient, and permit a short convalescence. To this list we add a further criterion : the operation should not cause deformity. An operation that has been used in Toronto for many years is the semitendinosus tenodesis. This operation has been practised in Italy since it was first described by Galeazzi in 1921, but it has been used less frequently elsewhere.