The V-shaped subscapularis tenotomy for anatomic total shoulder arthroplasty

Unicortical button fixation provides higher strength compared with transosseous repair for subscapularis tendon in total shoulder arthroplasty

BACKGROUND

Subscapularis tendon (SSc) dysfunction after total shoulder arthroplasty (TSA) results in poor functional outcomes. There have been numerous SSc repair constructs tested biomechanically and clinically; however, none has been demonstrated as superior. Newer techniques and implants have emerged but have not been fully tested.

HYPOTHESIS

We hypothesized that the unicortical button (UB) fixation would provide significantly improved restoration of the anatomic footprint and biomechanical properties compared with transosseous (TO) repair of the SSc.

METHODS

A digital footprint of SSc humeral insertion was obtained in 6 pairs of fresh-frozen cadaveric shoulders using a 3-dimensional digitizer. A complete SSc tear was created, and each pair of shoulders was randomized to either SSc repair with UB or TO repair. Each specimen underwent a cyclic loading protocol, followed by pull to failure. The failure load, elongation at failure, gapping failure, number of cycles until failure, the load at key gapping points (1 mm, 3 mm, 5 mm, and 10 mm), and the failure mode were recorded using high-resolution video recording. Three-dimensional surfaces of the insertion footprint and repair site were obtained, and surface areas were calculated using a custom MATLAB script and laser scanner. Paired t tests were conducted to compare differences between the 2 repair groups.

RESULTS

Failure load was significantly higher in the UB group (382.4 N ± 56.5 N) than in the TO group (253.6 N ± 103.4 N, P = .005). TO repair provided higher gapping at failure (28.8 mm ± 8.2 mm) than UB repair (10.4 mm ± 6.8 mm, P = .0017). UB repair had significantly higher load at the 1-mm, 5-mm, and 10-mm gapping than TO repair, with P = .042, P = .033, and P = .0076, respectively. There were no significant differences in elongation failure, the difference in footprint area from native to repair states, or the percentage of the restored footprint area between the groups (P = .26, P = .18, and P = .21, respectively).

CONCLUSIONS

The UB fixation showed a significantly lower gap at failure, higher failure load and number of cycles until failure, and higher gap loads than the traditional TO repair for SSc. Although more clinical research is necessary, the UB fixation that uses cortical bone presents promising results.

Biomechanics of subscapularis V-shaped tenotomy compared to standard tenotomy

BACKGROUND

Subscapularis function is critical after anatomic total shoulder arthroplasty (aTSA). Recently, however, a technique has been described that features a chevron or V-shaped subscapularis tendon cut (VT). This biomechanical study compared repair of the standard tenotomy (ST), made perpendicular to the subscapularis fibers, to repair of the novel VT using cyclic displacement, creep, construct stiffness, and load to failure.

METHODS

This biomechanical study used 6 pairs of fresh frozen paired cadaveric shoulder specimens. One specimen per each pair underwent VT, the other ST. Subscapularis tenotomy was performed 1 cm from the insertion onto the lesser tuberosity. For VT, the apex of the V was 3 cm from the lesser tuberosity. After tenotomy, each humerus underwent humeral head arthroplasty. Eight figure-of-8 sutures were used to repair the tenotomy (Ethibond Excel; Ethicon, US LLC). Specimens were cyclically loaded from 2 to 100 N at 45 degrees abduction at a rate of 1 Hz for 3000 cycles. Cyclic displacement, creep, and stiffness and load to failure were measured.

RESULTS

Cyclic displacement did not differ significantly between the ST and VT from 1 to 3000 cycles. The difference in displacement between the V-shaped and standard tenotomy at 3000 cycles was 1.57 mm (3.66 ± 1.55 mm vs. 5.1 ± 2.8 mm, P = .31, respectively). At no point was the V-shape tenotomy (VT) >3 mm of average displacement, whereas the standard tenotomy (ST) averaged 3 mm of displacement after 3 cycles. Creep was significantly lower for VT in cycles 1 through 3. For all cycles, stiffness was not significantly different in the VT group compared with the ST group. Load to failure was not statistically significant in the VT compared to the standard tenotomy throughout all cycles (253.2 ± 27.7 N vs. 213.3 ± 76.04 N; P = .25, respectively). The range of load to failure varied from 100 to 301 N for standard tenotomy compared with 216 to 308 N for VT.

CONCLUSION

This study showed that VT and ST demonstrated equivalent stiffness, displacement, and load to failure. VT had the benefit of less creep throughout the first 3 cycles, although there was no difference from cycle 4 to 3000. The VT had equivalent biomechanical properties to the ST at time zero, an important first step in our understanding of the technique. The VT technique warrants further clinical study to determine if the technique has clinical benefits over ST following aTSA.

Techniques for Managing the Subscapularis and Addressing Failures of the Tendon in Anatomic Total Shoulder Arthroplasty

Anatomic total shoulder arthroplasty (aTSA) is an accepted treatment for a variety of degenerative conditions of the glenohumeral joint. The manner in which the subscapularis tendon is handled during the approach in aTSA is not universally agreed on. Failure of the repair after aTSA has been shown to be associated with poorer outcomes in some cases. There is no consensus on how to treat failures, as all techniques described in the literature demonstrate shortcomings. The purpose of this review is to evaluate the methods of handling the tendon in aTSA and to review options for treating failure following surgery. [Orthopedics. 2023;46(5):e264-e272.].

Subscapular sparing approach for total shoulder arthroplasty: a systematic review and meta-analysis of comparative studies

Background

Total shoulder arthroplasty has been effective in treating primary glenohumeral arthritis surgically. However, the subscapularis (SSC) tendon must be released as part of the surgery's conventional approach, which could lead to postoperative problems and later tendon failure. Using a procedure that spares the tendon, Lafosse et al reported improved postoperative SSC performance. This meta-analysis will compare this approach to the standard one.

Methods

PubMed, Cochrane, and Google Scholar (pages 1-20) were searched till October 2022. The clinical outcomes consisted of the postoperative pain, adverse events, and range of motion.

Results

Only 3 studies were included in this meta-analysis. The subscapularis sparing approach tended to have better postoperative internal rotation (P = .06) and shoulder elevation (P = .1); however, the results were marginally statistically insignificant.

Conclusion

This is the first meta-analysis to compare the subscapularis sparing to the standard approach in total shoulder arthroplasty. Showing better postoperative range of motion (elevation and internal rotation), the SSC approach might be considered as a good substitute to the standard one. However, it is limited by the potentially limited exposure making it harder to use in muscular and obese patients. More randomized clinical trials are needed to reach more significant results and establish clearer indications of this approach.

Ultrasound-determined healing rates with subscapularis tenotomy versus peel after anatomic shoulder arthroplasty

BACKGROUND

Several techniques have been described for mobilizing the subscapularis tendon in anatomic total shoulder arthroplasty (TSA). The purpose of this study was to compare subscapularis tendon healing rates, as determined by ultrasound, in patients following anatomic TSA with either a subscapularis tenotomy or subscapularis peel.

METHODS

This study was a secondary analysis of patients from a previous randomized controlled trial in which patients underwent anatomic TSA and were randomized to either a tenotomy or peel approach. The primary outcome was postoperative tendon healing rates determined on ultrasound at >12 months after surgery. Secondary outcomes included postoperative tendon thickness measured on ultrasound; elbow position (neutral alignment in the belly-press position vs. posterior); internal rotation function measured with the third and fourth questions of the American Shoulder and Elbow Surgeons questionnaire; and Western Ontario Osteoarthritis of the Shoulder index. Radiographs were analyzed in patients with torn tendons.

RESULTS

One hundred patients were randomized to a tenotomy (n = 47) or peel (n = 53) approach. Postoperative ultrasound results were available in 88 patients. Tendon healing rates were 95% for tenotomy vs. 75% for peel (P = .011). The mean postoperative tendon thickness was 4 mm (standard deviation, 1.0 mm) and 4 mm (standard deviation, 1 mm) in the tenotomy and peel groups, respectively (P = .37). Internal rotation function was not associated with healing status (P = .77 and P = .22 for questions 3 and 4, respectively, of the American Shoulder and Elbow Surgeons questionnaire), nor was elbow position (P = .2) in the belly-press position.

DISCUSSION

We observed that subscapularis tenotomy had a higher healing rate than peel as determined by ultrasound in TSA patients. There was no statistically significant difference in postoperative tendon thickness in intact tendons as measured on ultrasound when comparing subscapularis mobilization techniques, nor was there any association between healing status and internal rotation function or elbow position.