BMP-12 Treatment of Adult Mesenchymal Stem Cells In Vitro Augments Tendon-Like Tissue Formation and Defect Repair In Vivo

We characterized the differentiation of rat bone marrow-derived mesenchymal stem cells (BM-MSCs) into tenocyte-like cells in response to bone morphogenetic protein-12 (BMP-12). BM-MSCs were prepared from Sprague-Dawley rats and cultured as monolayers. Recombinant BMP-12 treatment (10 ng/ml) of BM-MSCs for 12 hours in vitro markedly increased expression of the tenocyte lineage markers scleraxis (Scx) and tenomodulin (Tnmd) over 14 days. Treatment with BMP-12 for a further 12-hour period had no additional effect. Colony formation assays revealed that ∼80% of treated cells and their progeny were Scx- and Tnmd-positive. BM-MSCs seeded in collagen scaffolds and similarly treated with a single dose of BMP-12 also expressed high levels of Scx and Tnmd, as well as type I collagen and tenascin-c. Furthermore, when the treated BM-MSC-seeded scaffolds were implanted into surgically created tendon defects in vivo, robust formation of tendon-like tissue was observed after 21 days as evidenced by increased cell number, elongation and alignment along the tensile axis, greater matrix deposition and the elevated expression of tendon markers. These results indicate that brief stimulation with BMP-12 in vitro is sufficient to induce BM-MSC differentiation into tenocytes, and that this phenotype is sustained in vivo. This strategy of pretreating BM-MSCs with BMP-12 prior to in vivo transplantation may be useful in MSC-based tendon reconstruction or tissue engineering

Does humeral fixation technique affect long-term outcomes of total shoulder arthroplasty?

Background For anatomic total arthroscopic repair, cementless humeral fixation has recently gained popularity. However, few studies have compared clinical, radiographic, and patient-reported outcomes between cemented and press-fit humeral fixation, and none have performed follow-up for longer than 5 years. In this study, we compared long-term postoperative outcomes in patients receiving a cemented versus press-fit humeral stem anatomic arthroscopic repair. Methods This study retrospectively analyzed 169 shoulders that required primary anatomic total shoulder arthroplasty (aTSA). Shoulders were stratified by humeral stem fixation technique: cementation or press-fit. Data were collected pre- and postoperatively. Primary outcome measures included range of motion, patient reported outcomes, and radiographic measures. Results One hundred thirty-eight cemented humeral stems and 31 press-fit stems were included. Significant improvements in range of motion were seen in all aTSA patients with no significant differences between final cemented and press-fit stems (forward elevation: P=0.12, external rotation: P=0.60, and internal rotation: P=0.77). Patient reported outcome metrics also exhibited sustained improvement through final follow-up. However, at final follow-up, the press-fit stem cohort had significantly better overall scores when compared to the cemented cohort (visual analog score: P=0.04, American Shoulder and Elbow Surgeon Score: P<0.01, Simple Shoulder Test score: P=0.03). Humeral radiolucency was noted in two cemented implants and one press-fit implant. No significant differences in implant survival were observed between the two cohorts (P=0.75). Conclusions In this series, we found that irrespective of humeral fixation technique, aTSA significantly improves shoulder function. However, within this cohort, press-fit stems provided significantly better outcomes than cemented stems in terms of patient reported outcome scores. Level of evidenceIII

Evaluating the effects of age on the long-term functional outcomes following anatomic total shoulder arthroplasty

Background In the past decade, the number of anatomic total shoulder arthroplasty (aTSA) procedures has steadily increased. Patients over 65 years of age comprise the vast majority of recipients, and outcomes have been well documented; however, patients are opting for definitive surgical treatment at younger ages.We aim to report on the effects of age on the long-term clinical outcomes following aTSA. Methods Among the patients who underwent TSA, 119 shoulders were retrospectively analyzed. Preoperative and postoperative clinical outcome data were collected. Linear regression analysis (univariate and multivariate) was conducted to evaluate the associations of clinical outcomes with age. Kaplan-Meier curves and Cox regression analyses were performed to evaluate implant survival. Results At final follow-up, patients of all ages undergoing aTSA experienced significant and sustained improvements in all primary outcome measures compared with preoperative values. Based on multivariate analysis, age at the time of surgery was a significant predictor of postoperative outcomes. Excellent implant survival was observed over the course of this study, and Cox regression survival analysis indicated age and sex to not be associated with an increased risk of implant failure. Conclusions When controlling for sex and follow-up duration, older age was associated with significantly better patient-reported outcome measures. Despite this difference, we noted no significant effects on range of motion or implant survival. Level of evidenceIV

Temperature-dependent viscoelastic properties of the human supraspinatus tendon

Temperature effects on the viscoelastic properties of the human supraspinatus tendon were investigated using static stress-relaxation experiments and the quasi-linear viscoelastic (QLV) theory. Twelve supraspinatus tendons were randomly assigned to one of two test groups for tensile testing using the following sequence of temperatures: (1) 37, 27, and 17 °C (Group I, n=6), or (2) 42, 32, and 22 °C (Group II, n=6). QLV parameter C was found to increase at elevated temperatures, suggesting greater viscous mechanical behavior at higher temperatures. Elastic parameters A and B showed no significant difference among the six temperatures studied, implying that the viscoelastic stress response of the supraspinatus tendon is not sensitive to temperature over shorter testing durations. Using regression analysis, an exponential relationship between parameter C and test temperature was implemented into QLV theory to model temperature-dependent viscoelastic behavior. This modified approach facilitates the theoretical determination of the viscoelastic behavior of tendons at arbitrary temperatures

Anatomic total shoulder arthroplasty outcomes and implant survivability at greater than 22 years postoperative follow-up: A case series

Background: The modern anatomic shoulder implant has been available for five decades. Multiple short-to mid-term studies have reported favorable outcomes and predicted implant survival rates two decades post operatively. Yet, few studies have characterized the long-term (i.e., >20 years) clinical outcome expectations following shoulder replacement. Case details: In this case series, five patients underwent anatomic total shoulder arthroplasty for severe glenohumeral osteoarthritis with an average follow-up time of 25.4 years. The average postoperative Visual Analog Score, American Shoulder and Elbow Surgeon, and Simple Shoulder Test scores were 2.4/10.0, 61.7/100.0, and 7.0/12.0 respectively. Each patient saw improved range of motion outcomes that were at or below reported minimal clinically important differences. Glenoid loosening was present in two patients and humeral lucency was absent in all patients with available radiographic images (n ​= ​4). One shoulder required revision to reverse shoulder arthroplasty due to painful glenoid loosening 20.0 years after their primary anatomic replacement. Implant survival was 80% at 20-years and the mean implant survival time was predicted to be 28.0 ​± ​1.8 years. Conclusion: Anatomic total shoulder arthroplasty is a viable option for end stage osteoarthritis at long-term follow-up. However, patient expectations need to be curtailed as clinical outcomes will become lower as the implant ages and, subsequently, revision surgery will grow increasingly probable

Shoulder hemiarthroplasty for proximal humerus fracture outcomes after more than two decades: A case series

Background: Proximal humerus fractures can be fixed with shoulder hemiarthroplasty when joint preserving strategies are not feasible. Current literature has explored the outcomes of this intervention with short- and mid-term follow-up showing favorable results. However, since humerus fractures can occur in young individuals, it is important that we understand the long-term outlook of this treatment option. Case details: Five patients who had fractures of the proximal humerus underwent shoulder hemiarthroplasty here. At a average follow-up of 24.5 years, all patients were found to have acceptable patient-reported outcomes sustained range of motion, and no patient required a revision procedure. Patients achieved an average of 50°, T12, and 125° for external rotation, internal rotation, and forward elevation, respectively. American Shoulder and Elbow Surgeons, Simple Shoulder Test, Visual Analog Scale scores were 74/100, 8/12, and 2/10 on average, respectively. None of the five patients were found to have infection or wound complications. Radiographs showed that no patient had identifiable humeral lucency or glenohumeral joint inferior or anterior subluxation. Conclusion: Shoulder hemiarthroplasty is a viable surgical intervention for comminuted proximal humeral fractures. Over the long-term (i.e., >20 years), patients can expect sustained improvements in shoulder range of motion and acceptable function