In regard to HAD, there was a statistically significant difference noted postoperatively (P = .005) and at final follow-up (P = .025) between the LTO and ST cohorts. Saupe and colleagues13 demonstrated that a HAD <7 mm was considered abnormal and reflected subacromial space narrowing. The values noted in the LTO and ST patients on postoperative and final follow-up radiographs were statistically significant (Table 2), but not clinically relevant because both were >7 mm. A potential source for the variation in HAD may be due to X-ray position and angle.
Studies have shown a concern regarding the integrity of the subscapularis after tenotomy or peel used in TSA with abnormal subscapularis function.14,15 Miller and colleagues15 reported 41 patients, nearly two-thirds, of whom described subscapularis dysfunction. Those authors’ response to the poor clinical outcomes was to remove a fleck of bone with the tendon to achieve “bone-to-bone” healing.14 Gerber and colleagues16 reported on a series of patients using LTO and repair in TSA with 75% and 89% intact subscapularis function on clinical testing.16 Studies by Qureshi and colleagues17 and Scalise and colleagues18 showed similar results after LTO. Biomechanical studies have shown mixed results. Ponce and colleagues19 showed biomechanically superior results for LTO in comparison to the various repair techniques for ST. In another study, Giuseffi and colleagues20 showed no difference in LTO vs ST during biomechanical testing. In response to the increased concern regarding subscapularis integrity, Caplan and colleagues21 reported on 45 arthroplasties in 43 patients with improved postoperative testing with intact subscapularis testing in 90% to 100% of patients. A level 1 randomized control trial conducted by Lapner and colleagues22 did not demonstrate any clear clinical advantage of LTO vs ST. Controversy still exists regarding which is the preferred technique for TSA.
Sanchez-Sotelo and colleagues4 evaluated uncemented humeral components in 72 patients who underwent TSA. They found a humeral component was at risk for loosening if a radiolucent line ≥2 mm was present in at least 3 radiographic zones. They also evaluated tilt or subsidence by measurement and whether the components were observed to have changed. Their measured values correlated with their observed values. That study provided a benchmark for evaluation of loosening and subsidence used during this study.4 Although radiographic follow-up is limited in this study, we feel that any potential subsidence secondary to use of the LTO technique would be radiographically apparent at 1 year. There were 16 patients without adequate radiographic follow-up included in the study. However, we feel that this was not a large concern, because the study was adequately powered with the patients available to determine a difference based on subsidence.
CONCLUSION
We found no difference in subsidence, lucent lines >2 mm, posterior subluxation, and the Constant and DASH functional outcome scores when we compared TSA performed by a LTO with an ST technique with proximal collar press-fit humeral stem. These data cannot be extrapolated to metaphyseal fit stems, which may exhibit different settling characteristics in the setting of the LTO technique.
This paper will be judged for the Resident Writer’s Award.