The most important finding of this study is that LHBT tenotomy applied together with RC repair affects the clinical results and superior migration of the humerus. While LHBT tenotomy has a positive effect on clinical results, it causes the humerus to displace upwards due to removing its suppressive effect on the humeral head.
In our study, it was shown that the humeral head was displaced downwards due to RC repair and the suppressing effect of RC on the humeral head. But the most crucial thing in this study was to evaluate the difference between the two groups.
In a recent study showed that RC tear causes humeral migration by affecting the dynamic stabilizers of the shoulder [21]. In addition, about imaging methods to evaluate the displacement of the humeral head in RC tears, they evaluated the benefits of parameters such as upward migration index, inferior glenohumeral distance, acromial index and critical shoulder angle other than AHD. AHD is accepted as a prognostic indicator that affects functional outcome [5, 13, 14, 20].
In this study, pre-and postoperative AHD values measured from MRI and X-ray images are consistent with other studies [3]. Postoperative AHD values seemed to increase due to RC repair. The main point to be considered was that the difference between groups is significant. Less increase in AHD values in the tenotomy ( +) group than the tenotomy (-) group indicated the depressing effect of LHBT on the humerus head. Besides, most biomechanical studies on the function of LHBT have been conducted on cadavers and focused on the impact of GH on joint stability, with controversial results [11]. In vivo biomechanical studies have shown the upward migration of the humeral head in the absence or non-stimulation of LHBT; thus, it has been concluded that it functions as a humeral head suppressor [12].
Hirooka et al. [9] described an alternative method to measure the upper migration of the humerus and expressed the AHD value as a UMI ratio. Van de Sande and Rozing [24, 25], demonstrating a high correlation between plain films and computed tomography scans, determined the UMI measurement accuracy on plain radiographs. In our study, we found similar results in measurements made from MRI and X-ray images. This is because AHD is narrower in the tenotomy ( +) group. However, while the postop-preop UMI difference was substantial in MRI measurements in the total and tenotomy (-) group, this difference was not marked in X-ray images, suggesting that MRI performed more sensitive measurements.
In the study of Çetinkaya et al. HM and AHD were evaluated in four different patient groups, each of which included 30 patients [2]. HM and AHD measurements were made for all patients. The correlation of the two measurements was examined, they showed that AHD and HM measurements had a high correlation in all patient groups. In the present study, HM values gave similar results as AHD and UMI values. The absence of LHBT causes the humeral head center to be positioned above the glenoid center in the tenotomy ( +) group. Another study showed that the movement of the head in RC torn shoulders approximates the movement of normal shoulders after the biceps contraction. This suggests that the active biceps contraction can compensate for the suppressing function of the RC [12]. From a functional perspective, the evidence for the LHBT being a humeral head depressor and glenohumeral stabilizer has been demonstrated in both in vitro biomechanical studies and in vivo EMG studies. However, it is also important to recognize that even if the biceps muscle is not activated, the LHBT in a passive state still contributes to glenohumeral joint stability through barrier effects of the soft tissue alone [6].
In the study, the effect of biceps tenotomy on clinical results was evaluated with ASES and UCLA scores. Studies have found that LHBT tenotomy provides pain relief and it was also observed that biceps tenotomy with RC repair yielded better results [15, 28].
In our study, after an average of 33 months of follow-up, postoperative ASES scores were found to be significantly higher in the tenotomy ( +) group. This difference was thought to be due to the rapid improvement of daily activities evaluated in the ASES score after tenotomy.
The Popeye deformity and cramping pain are two critical reasons for not choosing tenotomy. Qiang et al. [30] showed in their study that the Popeye sign was minimally noticeable after tenotomy. On the other hand, they reported the incidence of Popeye's sign as 9.1% after tenotomy. In this study, the Popeye sign was seen in three (two male, one female) patients (10%) who underwent tenotomy, and the patients did not complain about this condition. Our findings were consistent with the findings of the previous study [10, 18].
One of the limitations of the study is the short-term follow-up period. After a mean follow-up of 33 months, no pathology was observed in the GH joint secondary to humeral migration. After long-term follow-up, it should be investigated whether any pathology due to humeral migration would develop in the GH joint and how the patients would be affected clinically by humeral migration. Another limitation is that the study was retrospective and the number of patients in the group was small. Finally, tenotomy was applied to the patients with biceps pathology, but not to the healthy ones, so randomization could not be performed.
In the light of the findings, biceps tenotomy clinically gave better results in ASES scores. While LHBT tenotomy clinically provided more improvement in patients, radiologically, it was observed that it caused superior humeral migration. Despite this, it was thought that the patients' clinical results were not negatively affected since humeral migration did not cause severe narrowing in AHD after RC repair.
Tenotomy should be performed in elderly patients with LHBT pathology. They will show a significant improvement clinically. The long-term outcomes of biceps tenotomy in younger active patients are unknown. In these patients, other treatment alternatives should be considered. Studies evaluating the effect of biceps tenotomy on long-term clinical and radiological results after RC repair are needed.