Osteoporosis pseudoglioma syndrome (OPPG) is a rare genetic disease that produces debilitating effects in the skeleton. OPPG is caused by mutations in LRP5, a WNT co-receptor that mediates osteoblast activity. WNT signaling through LRP5, and also through the closely related receptor LRP6, is inhibited by the protein sclerostin (SOST). It is unclear whether OPPG patients might benefit from the anabolic action of sclerostin neutralization therapy (an approach currently being pursued in clinical trials for postmenopausal osteoporosis) in light of their LRP5 deficiency and consequent osteoblast impairment. To assess whether loss of sclerostin is anabolic in OPPG, we measured bone properties in a mouse model of OPPG (Lrp5−/−), a mouse model of sclerosteosis (Sost−/−), and in mice with both genes knocked out (Lrp5−/−;Sost−/−). Lrp5−/−;Sost−/− mice have larger, denser, and stronger bones than do Lrp5−/− mice, indicating that SOST deficiency can improve bone properties via pathways that do not require LRP5. Next, we determined whether the anabolic effects of sclerostin depletion in Lrp5−/− mice are retained in adult mice by treating 17-week-old Lrp5−/− mice with a sclerostin antibody for 3 weeks. Lrp5+/+ and Lrp5−/− mice each exhibited osteoanabolic responses to antibody therapy, as indicated by increased bone mineral density, content, and formation rates. Collectively, our data show that inhibiting sclerostin can improve bone mass whether LRP5 is present or not. In the absence of LRP5, the anabolic effects of SOST depletion can occur via other receptors (such as LRP4/6). Regardless of the mechanism, our results suggest that humans with OPPG might benefit from sclerostin neutralization therapies.

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Background: Few large-scale series have described functional outcomes after distal triceps tendon repair. Predictors for operative success and a comparative analysis of surgical techniques are limited in the reported literature. Purpose: To evaluate short-term to midterm functional outcomes after distal triceps tendon repair in a broad patient population and to comparatively evaluate patient-reported outcomes in patients with and without pre-existing olecranon enthesopathy while also assessing for modifiable risk factors associated with adverse patient outcomes and/or revision surgery. Study Design: Case series; Level of evidence, 4. Methods: This study was a retrospective analysis of 69 consecutive patients who underwent surgical repair of distal triceps tendon injuries at a single institution. Demographic information, time from injury to surgery, mechanism of injury, extent of the tear, pre-existing enthesopathy, perioperative complications, and validated patient-reported outcome scores were included in the analysis. Patients with a minimum of 1-year follow-up were included. Results: The most common mechanisms of injury were direct elbow trauma (44.9%), extension/lifting exercises (20.3%), overuse (17.4%), and hyperflexion or hyperextension (17.4%). Eighteen patients were identified with pre-existing symptomatic enthesopathy, and 51 tears were caused by an acute injury. A total of 36 complete and 33 partial tendon tears were identified. Bone tunnels were most commonly used (n = 30; 43.5%), while direct sutures (n = 23; 33.3%) and suture anchors (n = 13; 18.8%) were also used. Perioperative complications occurred in 21.7% of patients, but no patients experienced a rerupture at the time of final follow-up. No statistically significant relationship was found between patient age ( P = .750), degree of the tear ( P = .613), or surgical technique employed ( P = .608) and the presence of perioperative complications. Conclusion: Despite the heightened risk of perioperative complications after primary repair of distal triceps tendon injuries, the current series found favorable functional outcomes and no cases of reruptures at short-term to midterm follow-up. Furthermore, age, surgical technique, extent of the tear, and mechanism of injury were not associated with adverse patient outcomes in this investigation. Pre-existing triceps enthesopathy was shown to be associated with increased complication rates.

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Objectives: Suture anchors are commonly utilized during arthroscopic rotator cuff repair (RCR). Recently, allsuture suture-anchor (ASSA) constructs have been introduced for RCR; however, the biomechanical properties of these implants are poorly understood. The purpose of this study was to compare the biomechanical properties of ASSA to conventional suture anchor (CSA) fixation during RCR. Methods: Fourteen fresh-frozen matched pair human cadaveric shoulders (average age 52 ± 13 years) with no documented prior rotator cuff tears or shoulder surgery were dissected. The supraspinatous tendon was isolated and detached from its footprint, and then was repaired in an anatomical position. Specimens were randomized into two repair constructs: Q-FIX double-loaded ASSA (N=7) and TWINFIX double-loaded conventional suture anchor (CSA) (N=7) (Smith & Nephew, Andover, MA). Each construct was cyclically loaded from 10 to 160N for 100 cycles at 100N/s, and then pulled to failure at 1mm/s starting from the zero position. Load, crosshead displacement, failure mode, and time were recorded. Correlations between BMD, tendon gage length, maximum load, and stiffness were assessed. The groups were statistically analyzed with independent samples t-test, Fisher's exact test, and a linear regression analysis, with p<0.05 considered significant.