Evaluation of the ‘Spaarne soft tissue procedure’ as a treatment for recurrent patellar dislocations: a four-in-one technique

Purpose: The ‘Spaarne soft tissue procedure’, is a 4-in-1 soft tissue procedure that treats recurrent patellar dislocations in the young and active population. The procedure has not yet described elsewhere. The purpose of this study is to analyse the redislocation rate and to evaluate the postoperative knee function and patient satisfaction. Methods: Twenty-seven patients (34 knees) underwent the four-in-one SST-procedure. The 4-step technique required a minor change in 2010, including the use of a smaller strip of the patellar tendon for transposition. After a median follow-up of 10.4 years, the redislocation rate was evaluated as the primary outcome measure. Secondary outcome measures were functional outcome (IKDC, Kujala, Lysholm and Tegner activity scale) and Numeric Rating Scales for satisfaction and pain. Results: Redislocation occurred in 8 cases (23.5%) and subluxation occurred in 13 cases (38.2%) post-surgery. A significant higher number of redislocations and subluxations were seen before 2010 (p = 0.04, p = 0.03). The median postoperative IKDC, Lysholm and Kujala scores for the total group were 54, 76 and 81 respectively. Pre- and postoperative Tegner activity scale were both level 3. Median NRS scores during rest, walking and sports were 1, 3 and 5 respectively. Satisfaction with the procedure was reported as ‘excellent’ or ‘good’ by 79% of the patients. Conclusion: Despite the high overall redislocation rate and increased pain scores, the SST-procedure shows to be a safe procedure in patients with recurrent patellar dislocations based on the cases after 2010. Mid- and long-term results show moderate to good functional outcomes and satisfaction. Level of evidence: Therapeutic retrospective cohort study, LEVEL II