Although critical bone loss for anterior instability is well defined, a clinically significant threshold of posterior bone loss has not been elucidated. Patients with failed arthroscopic posterior shoulder capsulolabral repair will have increased posterior glenoid bone loss with a defined critical threshold. Case control study; Level of evidence, 3. Athletes older than 18 years with unidirectional posterior instability treated with arthroscopic repair were evaluated at 2-year minimum follow-up. Failure was defined as revision surgery, American Shoulder and Elbow Surgeons (ASES) score of 5. Magnetic resonance imaging (MRI) measurements from 19 patients with failed arthroscopic posterior shoulder capsulolabral repair were compared with 56 patients whose surgery was successful. MRI measures included glenoid version, labral version, glenoid width, labral width, percentage bone loss using the circle technique, labral height, percent subluxation, and recently described measures of defect slope, bone loss angle, and defect length. The P value threshold was set at .05, and a multivariable logistic regression analysis was performed for evaluation of risk of surgical failure. Smaller glenoid width and greater percentage glenoid bone loss (25.5 ± 0.68 mm vs 28.8 ± 0.47 mm; P < .001; 6.8% ± 0.64% vs 4.6% ± 0.43%; P = .008) were seen in those patients with failed surgery. There was no difference in glenoid version or other measurements between the failures and nonfailures. A cutoff of 11% glenoid bone loss resulted in a 10.4 times statistically higher surgical failure rate, while a 15% bone loss resulted in a 24.4 times statistically higher failure rate. Six patients had >11% bone loss (range, 11.1 to 19.3) and 1 patient had >15% bone loss. Risk factors for failure of arthroscopic posterior shoulder capsulolabral repair include smaller glenoid bone width and greater percentage of glenoid bone loss. A threshold of 11% posterior glenoid bone loss implicated a 10 times higher surgical failure rate, while a threshold of 15% led to a 25 times higher surgical failure rate. Surgical failure of posterior capsulolabral repair, however, is relatively rare as it is an overall successful intervention.

Segmental bone defects that are caused by trauma, infection, tumor resection, or osteoporotic fractures present significant surgical treatment challenges. Host bone autograft is considered the gold standard for restoring function but comes with the cost of harvest site comorbidity. Allograft bone is a secondary option but has its own limitations in the incorporation with the host bone as well as its cost. Therefore, developing new bone tissue engineering strategies to treat bone defects is critically needed. In the past three decades, the use of stem cells that are delivered with different scaffolds or growth factors for bone tissue engineering has made tremendous progress. Many varieties of stem cells have been isolated from different tissues for use in bone tissue engineering. This review summarizes the progress in using different postnatal stem cells, including bone marrow mesenchymal stem cells, muscle-derived stem cells, adipose-derived stem cells, dental pulp stem cells/periodontal ligament stem cells, periosteum stem cells, umbilical cord-derived stem cells, peripheral blood stem cells, urine-derived stem cells, stem cells from apical papilla, and induced pluripotent stem cells, for bone tissue engineering and repair. This review also summarizes the progress using exosomes or extracellular vesicles that are delivered with various scaffolds for bone repair. The advantages and disadvantages of each type of stem cell are also discussed and explained in detail. It is hoped that in the future, these preclinical results will translate into new regenerative therapies for bone defect repair.

Background: Labral augmentation has emerged as an essential procedure to address a deficient or irreparable labrum while preserving native labral tissue and restoring the hip suction seal mechanism. Purpose: To evaluate midterm outcomes of arthroscopic hip labral augmentation for labral insufficiency after previous hip arthroscopy. Study Design: Case series; Level of evidence, 4. Methods: Patients were identified from a prospectively collected database who underwent arthroscopic hip labral augmentation between January 2011 and January 2017 with a minimum 3-year follow-up. Pre- and postoperative patient-reported outcome scores were compared and included the 12-Item Short Form Health Survey physical and mental component summaries, Western Ontario and McMaster Universities Osteoarthritis Index, modified Harris Hip Score (mHHS), and Hip Outcome Score (HOS) (Activities of Daily Living [ADL] and Sport). Postoperative Tegner Activity Scale and patient satisfaction (1-10) scores were also evaluated. The minimal clinically important difference (MCID) and Patient Acceptable Symptom State (PASS) between the preoperative and minimum 3-year follow-up scores were calculated. Results: A total of 88 patients (39 men, 49 women) underwent revision hip arthroscopy with labral augmentation. The average age was 32.8 ± 11 years. Of these, 77 patients (88%) were available for the minimum 3-year follow-up. The survivorship (absence of conversion to total hip arthroplasty) at 3 years and 5 years was 93% at both time points, with a mean survival time of 8.5 years (95% CI, 8.0-8.9). Eleven patients (14%) required revision arthroscopic surgery for continued pain. Revisions occurred at a mean of 2.6 ± 1.4 years after augmentation. The mean follow-up was 5.2 ± 1.2 years (range, 3-9 years). For patients not requiring subsequent surgery (n = 61), all patient-reported outcome measures significantly improved, which included a 20-point increase in HOS-ADL (MCID, 82%; PASS, 72%) and mHHS (MCID, 78%; PASS, 70%). The median postoperative Tegner score was 4 (range, 1-10). The median postoperative patient satisfaction score was 9 out of 10 (range, 1-10). Conclusion: Arthroscopic hip labral augmentation is a successful treatment option for patients with labral insufficiency after previous hip arthroscopy, demonstrating improved patient-reported outcomes and survivorship of 93% at 3 years and 5 years. This technique provides a valuable labral preservation option when addressing hip labral pathology when viable native labral tissue remains.