The mid-term outcomes on reverse total shoulder arthroplasty with isolated latissimus dorsi transfer in patients with isolated external rotation lag without pseudoparalysis: an average follow-up of 5 years

BACKGROUND: Reverse total shoulder arthroplasty (RTSA) is a well-established replacement strategy to treat irreparable massive rotator cuff tears and cuff tear arthropathy. In patients with forward (FF) deficits combined with a loss of external rotation (ER), RSA with latissimus dorsi transfer (LDT), which was initially used for brachial plexopathies, has been addressed to restore both functional deficits. The aim of the study is to assess mid-term clinical and radiological outcomes of concomitant RSA with LDT in patients with significant preoperative external rotation lag greater than 30 degrees without pseudoparalysis. We hypothesized that RTSA with concomitant isolated LDT can effectively improve ER range of motion (ROM) and ER lag postoperatively. METHODS: Our final case series included 26 patients who underwent RTSA concomitant with isolated LDT out of 341 RTSA's from July 2014 to July 2023. Inclusion criteria were (1) ER lag greater than 30 degrees and Goutallier grade greater than 3 in infrapinatus and teres minor muscle on preoperative MRI (Goutallier in J Shoulder Elbow Surg 12:550-554, 2003), (2) ROM in FF greater than 90 degrees, (3) diagnosis of massive irreparable rotator cuff tears and cuff tear arthropathy, according to Hamada classification (Hamada in Clinical Orthopaedics Related Res 469:2450-2460, 2011), and (4) a minimum postoperative follow-up of 2 years. Clinical outcome measures, which were evaluated preoperatively, postoperative 6 month, 12 month, and annually thereafter, were range of motion, muscle strength, visual analogue scale (VAS), Constant-Murley score, and American Shoulder and Elbow Society (ASES) score as well as complications. Radiologic outcomes measures included preoperative Hamada grade and Goutallier grades. RESULTS: The study was consisted of 10 male and 16 female patients, with an average follow-up of 5 years (range, 27 to 150 months). Preoperative range of motion showed FF 136', ER 28', internal rotation T9, and abduction 127'; in addition, ER lag was 32.6' at side and 26.2' at 90' abduction. Mean Goutallier grades of infraspinatus and teres minor were 3.9 and 3.7, respectively. Postoperative outcomes revealed that active range of ER did not significantly increase over time but that the degree of ER lag at side and at 90' abduction both showed statistically significant improvement at their final follow-up. Furthermore, the VAS and clinical scores, including ASES and Constant scores, all showed significant improvement at the final follow-up although muscle power including ER, belly press, lift off showed no improvement. CONCLUSION: In conclusion, the RTSA with isolated LDT in patients with irreparable massive rotator cuff tears with significant ER lag but without pseudoparalysis showed that ER lag was significantly improved postoperatively and remained stable through the mid-term follow-up without loss of IR. Regardless of prosthesis designs, LDT was able to restore functional ROM in ER and did not sacrifice its function in internal rotation in a combination with RSA. LEVEL OF EVIDENCE: Case Series, Level IV.