Poly(ADP-Ribose) Polymerases-Inhibitor Talazoparib Inhibits Muscle Atrophy and Fatty Infiltration in a Tendon Release Infraspinatus Sheep Model: A Pilot Study.

Structural muscle changes, including muscle atrophy and fatty infiltration, follow rotator cuff tendon tear and are associated with a high repair failure rate. Despite extensive research efforts, no pharmacological therapy is available to successfully prevent both muscle atrophy and fatty infiltration after tenotomy of tendomuscular unit without surgical repair. Poly(ADP-ribose) polymerases (PARPs) are identified as a key transcription factors involved in the maintenance of cellular homeostasis. PARP inhibitors have been shown to influence muscle degeneration, including mitochondrial hemostasis, oxidative stress, inflammation and metabolic activity, and reduced degenerative changes in a knockout mouse model. Tenotomized infraspinatus were assessed for muscle degeneration for 16 weeks using a Swiss Alpine sheep model (n = 6). All sheep received daily oral administration of 0.5 mg Talazoparib. Due to animal ethics, the treatment group was compared with three different controls from prior studies of our institution. To mitigate potential batch heterogeneity, PARP-I was evaluated in comparison with three distinct control groups (n = 6 per control group) using the same protocol without treatment. The control sheep were treated with an identical study protocol without Talazoparib treatment. Muscle atrophy and fatty infiltration were evaluated at 0, 6 and 16 weeks post-tenotomy using DIXON-MRI. The controls and PARP-I showed a significant (control p < 0.001, PARP-I p = 0.01) decrease in muscle volume after 6 weeks. However, significantly less (p = 0.01) atrophy was observed in PARP-I after 6 weeks (control 1: 76.6 ± 8.7%; control 2: 80.3 ± 9.3%, control 3: 73.8 ± 6.7% vs. PARP-I: 90.8 ± 5.1% of the original volume) and 16 weeks (control 1: 75.7 ± 9.9; control 2: 74.2 ± 5.6%; control 3: 75.3 ± 7.4% vs. PARP-I 93.3 ± 10.6% of the original volume). All experimental groups exhibited a statistically significant (p < 0.001) augmentation in fatty infiltration following a 16-week period when compared to the initial timepoint. However, the PARP-I showed significantly less fatty infiltration (p < 0.003) compared to all controls (control 1: 55.6 ± 6.7%, control 2: 53.4 ± 9.4%, control 3: 52.0 ± 12.8% vs. PARP-I: 33.5 ± 8.4%). Finally, a significantly (p < 0.04) higher proportion and size of fast myosin heavy chain-II fiber type was observed in the treatment group. This study shows that PARP-inhibition with Talazoparib inhibits the progression of both muscle atrophy and fatty infiltration over 16 weeks in retracted sheep musculotendinous units.

Clinical and radiographic long-term outcomes of hemiarthroplasty for complex proximal humeral fractures.

BACKGROUND: Hemiarthroplasty (HA) is a treatment option for complex proximal humeral fractures not suitable for conservative treatment or open reduction-internal fixation. Long-term outcomes using a large-metaphyseal volume prosthesis in the management of proximal humeral fractures have not been reported thus far. METHODS: Between 2006 and 2010, 41 patients with proximal humeral fractures were treated with HA at our institution (average age, 62 years; age range, 38-85 years). Nine patients underwent revision surgery, 3 were lost to follow-up, and 7 died unrelated to the index surgical procedure. Twenty-two patients were reviewed clinically and radiographically after a mean period of 10.4 years (range, 9-13 years). RESULTS: Of the 9 HA failures, 7 occurred within the first 2 postoperative years: 2 patients had infections and 5 had greater tuberosity nonunions or malunions. The other 2 patients underwent revision for rotator cuff deficiency >5 years after initial surgery. Among the patients available for final follow-up, the implant survival rate was 71% (22 of 31 patients). At final follow-up, these patients showed a mean relative Constant score of 76% (range, 49%-96%), mean active elevation of 116° (range, 60°-170°), and mean external rotation of 28° (range, 0°-55°). The majority had good or excellent internal rotation, with internal rotation to the 12th thoracic vertebra in 13 patients (59%) and to the eighth thoracic vertebra in 7 (31%). The mean Subjective Shoulder Value was 76% (range, 40%-100%). Clinical outcomes did not significantly deteriorate over a period of 10 years, except for flexion (P < .001) and internal rotation (P = .002). On analysis of greater tuberosity healing, 1 patient had a nonunion and 10 patients (45%) had a malunion, whereas the greater tuberosity had healed in an anatomic position in 12 patients (55%). Patients with a displaced malunion of the greater tuberosity did not have inferior clinical results at last follow-up. Only 2 patients showed glenoid erosion, and in no patients could stem loosening be identified at final follow-up. CONCLUSION: The revision rate following large-metaphyseal volume HA to treat a proximal humeral fracture was 29% after 10 years postoperatively, with failure within 2 years largely related to greater tuberosity nonunion or malunion and failure later related to rotator cuff insufficiency. Patients with a retained implant showed good clinical and radiographic long-term results, without relevant deterioration over time even when the greater tuberosity healed in a nonanatomic position.

Mid- to long-term clinical and radiological results of anatomic total shoulder arthroplasty in patients with B2 glenoids.

Background: Eccentric biconcave (B2) glenoid erosion in primary glenohumeral arthritis is common. There are serious concerns regarding the longevity of fixation of cemented glenoids if anatomic total shoulder arthroplasties (aTSAs) are used in B2 glenoid. The purpose of this study is to analyze the mid- to long-term results of aTSA with B2 glenoids. Methods: This is a retrospective study of a single center experience. Thirty patients (32 shoulders) at an average of 9.2 years (range, 5.0-16.6, ±3.2) after primary TSA were evaluated. Clinical and radiographic outcomes were analyzed. Results: The mean preoperative intermediate glenoid version was -14° ± 7° (range, -2° to -29°) and the mean humeral subluxation according to the plane of the scapula was 67% ± 9% (range, 49%-87%). There was a significant improvement for all the postoperative clinical outcome parameters including the mean absolute and relative Constant Score, subjective shoulder value, active elevation, external rotation, abduction, internal rotation, pain scores, and strength (P < .001). The complication rate was 15.6% and the revision rate was 12.5% at a mean follow-up of 9.2 years (range, 5.0-16.6, ±3.2). The estimated survivorship without revision was 94% at 5 years and 85% at 10 years (12.1-14.7 years). The survival rate without advanced glenoid component loosening (defined as Lazarus grade ≥ 4 or modified Molé scores ≥ 6) was 91% at 5 years and 84% at 10 years (12.2-15.8 years). Conclusion: In this case series, aTSA with asymmetric reaming for the treatment of shoulder osteoarthritis with milder forms of B2 glenoid is a viable option with good to excellent clinical results and an 85% prosthetic survivorship at 10 years.

Inadvertent, intraoperative, non- to minimally displaced periprosthetic humeral shaft fractures in RTSA do not affect the clinical and radiographic short-term outcome.

INTRODUCTION: Little information is available on the clinical and radiographic outcome of intraoperative, non- to minimally displaced humeral fractures that occur during implantation of a stemmed, reverse shoulder prosthesis but are only recognized on routine postoperative radiographs. The goal of this study is to report the clinical and radiographic outcome for this rarely reported fracture type. MATERIALS AND METHODS: 39 conservatively treated non- to minimally displaced intraoperative periprosthetic humeral fractures after stemmed RTSA were detected from our radiographic database between 1.1.2006 and 31.1.2018. Exclusion criteria were lack of patient consent, preoperative humeral fracture, and revision arthroplasties. Clinical (absolute and relative Constant score, the Subjective Shoulder Value) and radiographic (conventional radiographs) assessment was performed preoperatively, at 6 weeks (only radiographically) and at latest follow-up with a minimum follow-up of 2 years. RESULTS: 35 patient's with a mean age of 72 years (range 32-88, SD ± 11 years) and a mean follow-up of 53 months (range 24-124, SD ± 31) were included in the study. At latest follow-up, all clinical outcome parameters except external rotation improved significantly. A complication rate of 17% (n:6) was recorded. At 6 weeks after the index surgery, none of the radiographs showed a fracture displacement or a sintering of the stem. At latest follow-up, all fractures were healed and no stem loosening was observed in any of the shoulders. CONCLUSIONS: Non- to minimally displaced intraoperative periprosthetic humeral fractures in RTSA have an incidence of about 5% in this series of mainly uncemented press-fit stems. They generally heal without any further treatment and are not associated with stem loosening or compromise the clinical outcome after primary RTSA. Except slight restriction in the postoperative rehabilitation protocol, no further attention or action is needed.

Nonoperatively managed small- to medium-sized subscapularis tendon tears: magnetic resonance imaging evaluation with a minimum of 5 years of follow-up.

BACKGROUND: Isolated or combined subscapularis (SSC) tendon tears are frequently found in patients with shoulder pain. The purpose of this study was to evaluate the structural changes associated with SSC tear in a consecutive series of patients with nonoperatively treated small size to midsize SSC tendon tears using magnetic resonance imaging (MRI). METHODS: In this retrospective case series, all patients with an isolated or combined SSC tendon tear treated nonoperatively between 1999 and 2019 were identified from our MRI and clinical databases. Twenty-one patients with a mean age of 52.6 years (range 26.6-64.8, standard deviation 9.3) with a second MRI scan at a minimum of 5 years of follow-up were enrolled. The mean follow-up was 8.6 years (range 5.6-12.6, standard deviation 1.8). Initial and last follow-up MRI scans were used to determine concomitant cuff lesions, size of the SSC tear, fatty infiltration of the SSC muscle, and biceps pathology. RESULTS: Five patients had an isolated SSC lesion; 7 patients had a concomitant tear of the supraspinatus, and 9 patients had a supraspinatus and anterior infraspinatus tendon tear. At diagnosis, 14 patients had a type 1 SSC lesion as classified by Lafosse et al, 4 patients had type 2, and 3 patients had type 3 lesions. Nineteen patients (90%) were found to have an SSC tear progression of at least one Lafosse grade (P < .001); however, no tear had progressed to an irreparable type lesion (defined as Lafosse type 5). In addition, the size of SSC tendon tears increased significantly from 75 mm2 to 228 mm2 (P < .001). At the final MRI scan, the grading of fatty infiltration increased by 1 grade in 4 cases and by 2 grades in 4 cases (P = .042). At the final follow-up, in eight patients, the condition of the long head of biceps tendon was unchanged from the initial MRI; in nine patients, there was a newly subluxated biceps tendon, and in 6 patients, there was a newly ruptured long head of biceps tendon (P < .001). CONCLUSION: After a mean of 8.6 years, almost all nonoperatively treated SSC tendon tears had increased in size, but only one-third showed additional progression of muscle fatty degeneration on MRI scan. None of the SSC lesions became irreparable during the observation period.

Muscle Degeneration Induced by Sequential Release and Denervation of the Rotator Cuff Tendon in Sheep.

BACKGROUND: In a sheep rotator cuff model, tenotomy predominantly induces fatty infiltration, and denervation induces mostly muscle atrophy. In clinical practice, myotendinous retraction after tendon tear or lateralization after tendon repair tear may lead to traction injury of the nerve. PURPOSE/HYPOTHESIS: To analyze whether an additional nerve lesion during rotator cuff repair leads to further degeneration of the rotator cuff muscle in the clinical setting. We hypothesized that neurectomy after tendon tear would increase atrophy as well as fatty infiltration and that muscle paralysis after neurectomy would prevent myotendinous retraction after secondary tendon release. STUDY DESIGN: Controlled laboratory study. METHODS: Twelve Swiss alpine sheep were used for this study. For the 6 sheep in the tenotomy/neurectomy (T/N) group, the infraspinatus tendon was released; 8 weeks later, the suprascapular nerve was transected. For the 6 sheep in the neurectomy/tenotomy (N/T) group, neurectomy was performed, and the infraspinatus was tenotomized 8 weeks later. All sheep were sacrificed after 16 weeks. Magnetic resonance imaging (MRI) was performed before the first surgery (baseline) and then after 8 and 16 weeks. The MRI data were used to assess muscle volume, fat fraction, musculotendinous retraction, pennation angle, and muscle fiber length of the infraspinatus muscle. RESULTS: Three sheep (2 in the T/N and 1 in the N/T group) had to be excluded because the neurectomy was incomplete. After 8 weeks, muscle volume decreased significantly less in the T/N group (73% ± 2% of initial volume vs 52% ± 7% in the N/T group; P < .001). After 16 weeks, the mean intramuscular fat increase was higher in the T/N group (36% ± 9%) than in the N/T group (23% ± 6%), without reaching significance (P = .060). After 16 weeks, the muscle volumes of the N/T (52% ± 8%) and T/N (49% ± 3%) groups were the same (P = .732). CONCLUSION: Secondary neurectomy after tenotomy of a musculotendinous unit increases muscle atrophy. Tenotomy of a denervated muscle is associated with substantial myotendinous retraction but not with an increase of fatty infiltration to the level of the tenotomy first group. CLINICAL RELEVANCE: Substantial retraction, which is associated with hitherto irrecoverable fatty infiltration, should be prevented, and additional neurogenic injury during repair should be avoided to limit the development of further atrophy.

Is suture cerclage fixation a valid treatment for intraoperative nondisplaced calcar fractures in reverse total shoulder arthroplasties?

BACKGROUND: Implantation rates of reverse total shoulder arthroplasties continue to grow worldwide. Despite satisfying results, a distinct number of complications persist. Intraoperative fractures of the humeral shaft might occur in a certain number of cases. The literature is sparse regarding incidence and treatment options. This study analyzed the treatment using suture cerclage or stainless-steel-cable cerclage. METHODS: Our prospectively followed-up cohort of 860 patients who received primary reverse total shoulder arthroplasty in a tertiary referral hospital between September 2005 and August 2018 was screened for intraoperative medial humeral calcar fractures. The patients were retrospectively analyzed as per the treatment algorithm using (1) suture cerclage with FiberWire, (2) cable cerclage with stainless steel cable, or (3) no intervention. The outcome was radiologically and clinically (Subjective Shoulder Value and Constant score) evaluated. RESULTS: A total of 39 (4.5%) intraoperative calcar fractures of the humeral shaft were identified with 29 cases available for analysis at a mean follow-up time of 52 ± 27 months. Sixteen of them were treated with suture cerclage, 7 with metal cable cerclage, and 6 without intervention. All fractures were nondisplaced or could be reduced anatomically and healed without any stem subsidence or loosening within the first 4.5 months. The intervention groups reached similar values for the Subjective Shoulder Value (68%±27% vs. 79%±19%, suture vs. cable) and relative Constant score (65 % ± 25 % vs. 75 % ± 23). CONCLUSION: Intraoperative medial calcar fractures can be sufficiently treated with metal or suture cerclage fixation. High-strength polyblend-polyethylene sutures seem to be a valid therapeutic option for selected medial calcar fractures of the humerus. In selected cases, however, benign neglect can result in excellent results as well.

Factors influencing functional internal rotation after reverse total shoulder arthroplasty.

BACKGROUND: Functional internal rotation (fIR) of the shoulder is frequently limited after reverse shoulder arthroplasty (RTSA). The objective of this study was to study a cohort of satisfied patients after RTSA who had comparable active mobility except for fIR and to identify factors associated with selective loss of fIR. METHODS: A retrospective cohort study was conducted to compare 2 patient groups with either poor (≤ 2 points in the Constant-Murley score [CS]) or excellent (≥8 points in CS) fIR after RTSA at a minimum follow-up of 2 years. Influencing factors (demographic, surgical or implant related, radiographic parameters) and clinical outcome were analyzed. RESULTS: Fifty-two patients with a mean age of 72.8 (±9.3) and a mean follow-up of 41 months were included in the IR≤2 group and 63 patients with a mean age of 72.1 (±8.0) and a mean follow-up of 59 months in the IR≥8 group. All patients had undergone RTSA with the same implant type and only 2 different glenosphere sizes (36 and 40) for comparable indications. A multivariate analysis identified the following significant risk factors for poor postoperative fIR: poor preoperative fIR (pts in CS: 3 [range: 2-6] vs. 6 [range: 4-8], P<.0001), smoking (17.3% vs. 6.5%, P = .004), male gender (59.6% vs. 31.7%, P = .002), less preoperative to postoperative distalization of the greater tuberosity (Δ 19.4 mm vs. 22.2 mm, P = .026), a thin humeral insert (≤3 mm: 23.1% vs. 54.8%, P = .039), and a high American Society of Anesthesiologists score (≤ III: 30.8% vs. 14.3%, P = .043). Subscapularis repair status and glenosphere size had no influence on fIR. Clinical outcome scores improved in both groups from preoperatively to last follow-up. The IR≥8 group had overall significantly better outcome scores compared to the IR≤2 group (Δ 9.3% SSV and Δ 9.5% relative CS, P < .0001). There was no difference in CS between the cohorts when the score for fIR was discarded. CONCLUSION: Independent risk factors for poor postoperative fIR after RTSA are poor preoperative fIR, smoking, male gender, less preoperative to postoperative distalization of the greater tuberosity, a thin humeral insert height, and a high American Society of Anesthesiologists score. Except for male gender, these factors are modifiable. These findings may be a valuable addition to patient counselling as well as preoperative planning and preoperative and intraoperative decision-making. The relevance of fIR for overall satisfaction is substantiated by this study.

Deep surgical site infections following double-dose perioperative antibiotic prophylaxis in adult obese orthopedic patients.

BACKGROUND: Obesity is a risk factor for surgical site infections (SSI). Based on retrospective comparisons and pharmacology, many orthopedic centers have adopted weight- or body mass index (BMI)-related antibiotic prophylaxis. METHODS: Double-dose prophylaxis was introduced in March 2017 for patients weighting >80 kg. The period April 2014 to March 2017 ('before') was compared to the period March 2017 to June 2019 ('after') regarding the impact on deep SSIs. RESULTS: A total of 9318 surgeries 'before' were compared to 7455 interventions 'after' the introduction of double-dose prophylaxis. Baseline demographic characteristics (age, sex, BMI, American Society of Anesthesiologists score, and duration of surgery) were similar. In the period 'after', 3088 cases (3088/16 773; 18%) received double-dose prophylaxis. Overall, 82 deep SSIs were observed (0.5%). The pathogens were resistant to the standard cefuroxime prophylaxis in 30 cases (30/82; 37%). Excluding these prophylaxis-resistant cases and all of the five hematogenous SSIs, the remaining 47 SSIs (57%) could have been prevented by the preceding prophylaxis. Double-dosing of parenteral cefuroxime from 1.5 g to 3.0 g in obese patients did not reduce deep SSIs (hazard ratio 0.7, 95% confidence interval 0.3-1.6). In the direct group comparison among obese patients >80 kg, the double-dose prophylaxis equally failed to alter the SSI risk (3088/16 726 non-infections vs 8/47 SSI despite double-dose prophylaxis; Chi-square test, P = 0.78). CONCLUSIONS: In this single-center before-and-after study with almost 17 000 orthopedic surgeries in adult patients, systemic doubling of the perioperative antibiotic prophylaxis in obese patients clinically failed to reduce the overall deep SSI risk.

Joint-line medialization after anatomical total shoulder replacement requires more rotator cuff activity to preserve joint stability.

BACKGROUND: The biomechanical effects of joint-line medialization during shoulder surgery are poorly understood. It was therefore the purpose of this study to investigate whether medialization of the joint line especially associated with total shoulder arthroplasty leads to changes in the rotator cuff muscle forces required to stabilize the arm in space. METHODS: A validated computational 3-D rigid body simulation model was used to calculate generated muscle forces, instability ratios, muscle-tendon lengths and moment arms during scapular plane elevation. Measurements took place with the anatomical and a 2 mm and 6 mm lateralized or medialized joint line. RESULTS: When the joint line was medialized, increased deltoid muscle activity was recorded throughout glenohumeral joint elevation. The rotator cuff muscle forces increased with medialization of the joint line in the early phases of elevation. Lateralization of the joint line led to higher rotator cuff muscle forces after 52° of glenohumeral elevation and to higher absolute values in muscle activity. A maximum instability ratio of >0.6 was recorded with 6 mm of joint-line medialization. CONCLUSION: In this biomechanical study, medialization and lateralization of the normal joint line during total shoulder arthroplasty led to substantial load changes on the shoulder muscles used for stabilizing the arm in space. Specifically, medialization does not only lead to muscular shortening but also to increased load on the supraspinatus tendon during early arm elevation, the position which is already most loaded in the native joint.

The critical shoulder angle does not change over time: a radiographic study.

BACKGROUND: The anatomy of the scapula may predispose individuals to develop shoulder pathologies. The purpose of this study was to determine if the scapular anatomy, in particular the critical shoulder angle (CSA), changes over a long-term follow-up, or if it is a stable parameter. We hypothesized that increasing age would not influence the scapular morphology. METHODS: We analyzed shoulder radiographs in our database from 2002 to 2019 to extract radiographs at an interval of at least 10 years. Radiographic analysis included measuring the CSA and assessing the acromion type according to Bigliani and Morrison, the posterior acromial height and the posterior acromial tilt. RESULTS: A total of 41 patients (47 shoulders) with a mean age of 53 years (range, 15-76; standard deviation [SD], ±14) fulfilled the inclusion criteria. The mean interval between the 2 sets of radiographs was 12 years (range, 10-16; SD ±2).The mean CSA did not change significantly with 34° (range, 20-41; SD ±4) at the first and 34° (range, 19-44; SD ±5) (P = .597) at the second assessment. On the initial lateral radiographs ("Neer view"), there were 11 type 1 (24%), 32 type 2 (70%), and 3 type 3 (6%) acromia according to Bigliani and Morrison. At the second assessment, there were 16 type 1 (34%), 28 type 2 (60%), and 3 type 3 (7%). Between both sets of radiographs, 11 were different (23%), without a trend in the type of change being discernible. The posterior acromial height was stable with 19 mm (range, 2-36; SD ±8) at the first and 18 mm (range, 5-38; SD ±8) at the second assessment (P = .186). The posterior acromion tilt changed from 59° (range, 34-81; SD ±10) to 62° (range, 30-81; SD ±10) (P < .001). Among 6 cases with rotator cuff tears (RCTs) already at the first assessment, the CSA did not change significantly at 10 years' follow-up (P = .414). Among the 10 cases with new RCTs at the second assessment, the CSA did not change significantly at 10 years' follow-up from 34° (range, 25-41; SD ±5) to 35° (range, 24-44; SD ±6) (P = .510). In the group of 31 shoulders without RCT, the mean CSA at the first assessment of 34° (range, 28-41; SD ±3) stayed also stable with 34° (range, 28-40; SD ±3) (P = .796). CONCLUSION: The CSA is an anatomical parameter of the scapula that does not change in size after closure of the physes.

No difference in long-term outcome between open and arthroscopic rotator cuff repair: a prospective, randomized study.

BACKGROUND: Arthroscopic rotator cuff repair techniques have almost replaced open repairs. Short- and mid-term studies have shown comparable outcomes, with no clear superiority of either procedure. The aim of this study was to compare the long-term clinical and imaging outcomes following arthroscopic or open rotator cuff repair. METHODS: Forty patients with magnetic resonance imaging (MRI)-documented, symptomatic supraspinatus or supraspinatus and infraspinatus tears were randomized to undergo arthroscopic or open rotator cuff repair. Clinical and radiographic follow-up was obtained at 6 weeks, 3 months, 1 year, 2 years, and >10 years postoperatively. Clinical assessment included measurement of active range of motion, visual analog scale score for pain, functional scoring according to the Constant-Murley score (CS), and assessment of the Subjective Shoulder Value. Imaging included conventional radiography and MRI for the assessment of cuff integrity and alteration of the deltoid muscle. RESULTS: We enrolled 20 patients with a mean age of 60 years (range, 50-71 years; standard deviation [SD], 6 years) in the arthroscopic surgery group and 20 patients with a mean age of 55 years (range, 39-67 years; SD, 8 years) in the open surgery group. More than 10 years' follow-up was available for 13 patients in the arthroscopic surgery group and 11 patients in the open surgery group, with mean follow-up periods of 13.8 years (range, 11.9-15.2 years; SD, 1.1 years) and 13.1 years (range, 11.7-15 years; SD, 1.1 years), respectively. No statistically significant differences in clinical outcomes were identified between the 2 groups: The median absolute CS was 79 points (range, 14-84 points) in the arthroscopic surgery group and 84 points (range, 56-90 points) in the open surgery group (P = .177). The median relative CS was 94% (range, 20%-99%) and 96% (range, 65%-111%), respectively (P = .429). The median Subjective Shoulder Value was 93% (range, 20%-100%) and 93% (range, 10%-100%), respectively (P = .976). MRI evaluation showed a retear rate of 30% equally distributed between the 2 groups. Neither fatty infiltration of the deltoid muscle, deltoid muscle volume, nor the deltoid origin were different between the 2 groups. CONCLUSION: In a small cohort of patients, we could not document any difference in clinical and radiographic outcomes at long-term follow-up between arthroscopic and open rotator cuff repair. The postulated harm to the deltoid muscle with the open technique could not be confirmed.

Radiographic performance depends on the radial glenohumeral mismatch in total shoulder arthroplasty.

BACKGROUND: Optimal radii of curvature of the articulating surfaces of the prosthetic components are factors associated with the longevity of cemented glenoid components in anatomical total shoulder arthroplasty. It was the purpose of this study, to evaluate the radiographic and clinical performance of an anatomical glenoid component of a total shoulder arthroplasty (TSA) with respect to radial mismatch of the glenoid and humeral component. METHODS: In a retrospective study 75 TSA were analyzed for their clinical and radiographic performance with computed tomography by independent examiners using an established methodology. The study group was divided in two groups, one with mismatch < 4.5 mm (n:52) the others with mismatch ≥4.5 mm (n:23) and analyzed for confounding variables as indication, primary or revision surgery, age, gender, glenoid morphology and implant characteristics. RESULTS: The mean glenohumeral radial mismatch was 3.4 mm (range 0.5-6.9). At median follow-up of 41 months (range 19-113) radiographic loosening (defined as modified Molé scores ≥6) was present in 7 cases (9.3%). Lucencies around the glenoid pegs (defined as modified Molé score ≥ 1) were present in 34 cases (45%). Radiolucencies were significantly associated with a radial mismatch < 4.5 mm (p = 0.000). The pre- to postoperative improvements in Subjective Shoulder Value and absolute Constant Score were significantly better in the group with a mismatch ≥4.5 mm (p = 0.018, p = 0.014). CONCLUSION: A lower conformity of the radii of humerus and glenoid seems to improve the loosening performance in TSA. Perhaps cut-off values regarding the recommended mismatch need to be revalued in the future.

Arthroscopic repair of isolated subscapularis tears: clinical outcome and structural integrity with a minimum follow-up of 4.6 years.

BACKGROUND: After isolated subscapularis repair, improvement in shoulder function has been reported at short-term review. The purpose of this study was to determine whether arthroscopic subscapularis repair provides durable improvement in objective and subjective shoulder function with a low structural retear rate. METHODS: All patients treated with arthroscopic repair of an isolated subscapularis tear between August 2003 and December 2012 with a minimum follow-up period of 4.6 years were identified from our database. A number of patients in our study cohort underwent a prior complete midterm assessment, which allowed a subgroup analysis to detect changes in structural integrity and corresponding function. Clinical and radiographic outcomes, including outcomes on conventional radiography and magnetic resonance imaging or ultrasound, were assessed. RESULTS: The study enrolled 36 shoulders with a mean patient age of 57.7 years (range, 31-75 years; standard deviation, 10.6 years). The mean follow-up period was 8.6 years (range, 4.6-13.9 years; standard deviation, 2.44 years). Internal rotation to the thoracic vertebrae was achieved in 94% of cases and was significantly improved (P < .001) compared with the preoperative situation. The mean relative Constant score improved from 68% preoperatively to 93% at final follow-up (P < .001). Magnetic resonance imaging evaluation showed a rerupture rate of 2.7% (1 of 36 shoulders). Twenty patients underwent previous complete midterm assessment (mean, 2.9 years; range, 1-4.5 years), with comparisons between midterm and long-term follow-up showing comparable results without statistically significant deterioration. CONCLUSIONS: Functional and subjective improvements in shoulder function are maintained at a mean follow-up of more than 8 years after isolated subscapularis repair and are associated with a low structural failure rate of the repair.

Mechanisms of Suture Integration in Living Tissue: Biomechanical and Histological In Vivo Analysis in Sheep.

The potential of nonabsorbable suture material to augment tissue strength in the long-term is by far not exploited by most of the currently used sutures. The authors hypothesized that different sutures yield specific histological tissue reactions associated with specific mechanical shear resistance of the suture against the tissue. Four different suture types (Orthocord, Ethibond, FiberTape, and FiberWire) were implanted in 36 sheep shoulders (supraspinatus/greater tuberosity). One thread at each time point (6, 16, and 22 weeks) was used for histology, and 11 threads at each time point (0, 6, 16, and 22 weeks) were used for biomechanical longitudinal pullout testing. Histology included tissue maturity, activity of tissue reaction, and invasion of cells and tissue into the suture material. Fiber-Tape had the highest mean pullout strength at 6, 16, and 22 weeks of 4.4 N/cm (SD, 2.1 N/cm), 10.1 N/cm (SD, 5.1 N/cm), and 12.8 N/cm (SD, 6.0 N/cm), respectively. However, general pullout strength at 22 weeks was surprisingly low, particularly for Ethibond, Orthocord and FiberWire. The overall maturity of the surrounding tissue correlated (r=0.84, P=.001) with mechanical performance. Interestingly, in all 4 suture types, an intimate in- and on-growth of fibrous tissue to the filaments and into the space between suture fibers could be shown. However, for Ethibond, Orthocord, and FiberWire, the authors found an unexpected circumferential space around the sutures, often forming an inner and outer capsule, separating the sutures from the surrounding tissue with a shifting layer. [Orthopedics. 2019; 42(3):168-175.].

Reverse shoulder arthroplasty in the treatment of glenohumeral instability.

BACKGROUND: Glenohumeral instability is a rare indication for primary reverse total shoulder arthroplasty (RTSA), accounting for fewer than 1% of the indications in the literature. The aim of this study was to analyze the clinical and radiographic outcomes of RTSA for recurrent instability after failed operative repair or instability associated with major bone loss in elderly patients. METHODS: A retrospective matched case-control study was performed. We compared 11 shoulders treated with RTSA for instability (cases) with 22 matched shoulders treated with RTSA for rotator cuff insufficiency (controls). Clinical and radiographic outcomes were compared. RESULTS: The median follow-up period was 74 months (interquartile range [IQR], 18 months; range, 22-171 months) in cases and 70 months (IQR, 13 months; range, 23-172 months) in controls. The median age was 74 years (IQR, 18 years) in the case group and 70 years (IQR, 13 years) in the control group. No significant differences were found between the 2 groups in satisfaction scores, preoperative and postoperative absolute and relative Constant scores, and complication rates. Active range of motion tended to be superior in the controls for mean flexion (130° vs. 110°, P = .15), abduction (143° vs. 100°, P = .16), and external rotation (28° vs. 20°, P = .86) without the differences reaching statistical significance, possibly because of the small sample size. Postoperative dislocation was not recorded in cases or controls, but subjective insecurity regarding stability was reported once in each group. CONCLUSION: RTSA seems to represent a valuable treatment option for glenohumeral instability in an elderly population with large bone loss or as a salvage procedure after failed operative glenohumeral stabilization. Postoperative instability was not observed in the case and control groups.

Critical shoulder angle: Acromial coverage is more relevant than glenoid inclination.

It is still unknown whether glenoid inclination or lateral acromial roof extension is a more important determinant for development of rotator cuff tears (RCT) or osteoarthritis (OA) of the shoulder. It was the purpose of this study, to evaluate whether there is a potential predominance of one of these factors in pathogenesis of RCT or concentric OA. We analyzed 70 shoulders with advanced degenerative RCT and 54 shoulders with concentric OA undergoing primary shoulder arthroplasty (anatomical or reverse) using antero-posterior radiography and multiplanar computed tomography. The two groups were compared in relation to glenoid inclination, lateral acromion roof extension, acromial height, and critical shoulder angle (CSA). All measured parameters were highly significantly different between RCT and concentric OA (p < 0.001). Based on Cohen's d effect size, group differences were most distinct in lateral acromial roof extension (1.36x-ray , 0.92ct ) compared with acromial height (1.06x-ray , 0.73ct ) and glenoid inclination (0.60x-ray , 0.61ct ). However, no single factor showed an effect size which was as high as that of the CSA (1.63x-ray ). Interestingly, a ratio of lateral acromion roof extension and acromial height could enhance the effect size (1.60x-ray , 1.16ct ) near to values of the CSA (1.63x-ray ). In summary, lateral acromial roof extension has a greater influence in pathogenesis of degenerative RCT and concentric OA than acromial height or glenoid inclination. © 2018 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res.

Chronic anterior sternoclavicular instability: technique and results of corrective clavicular osteotomy.

BACKGROUND: Chronic anterior sternoclavicular (SC) instability is a rare but potentially disabling condition. It can arise in conjunction with trauma or hyperlaxity, or both. Numerous surgical techniques have been described, but no gold standard exists. SC instability is often position-dependent and can be reduced with the arm in a specific position. METHODS: To directly address this issue, we used a technique of corrective osteotomy of the clavicle with the goal to reorient the articular portion of the medial end of the clavicle so that it remains stable in all functional positions of the arm. To illustrate the technique and the correction in space, we performed postoperative 3-dimensional computed tomography analyses of the shoulder girdle of 4 patients. Clinical scores were obtained at the final follow-up and compared with preoperative scores. RESULTS: Mean follow-up was 64 months (range, 19-191 months). The mean Constant score improved from 58 (range, 45-68) preoperatively to 73 (range, 69-84) postoperatively and the Subjective Shoulder Value from 42 (range, 15-80) to 79 (range, 50-100). All patients reported good or very good stability of the SC joint at the last follow-up. We recorded no intraoperative or direct postoperative complications. During follow-up, 3 patients underwent removal of the plate, 1 of them for plate breakage. The mean postoperative correction for combined rotations is given as a 3-dimensional angle and averaged 28.0° (range, 8.6°-39.7°). CONCLUSION: In this pilot study, medial corrective clavicular osteotomy using the described technique treated anterior SC instability with improvement of clinical shoulder function scores and good patient satisfaction. The technique appears simple and safe and deserves further evaluation.

Different acromial roof morphology in concentric and eccentric osteoarthritis of the shoulder: a multiplane reconstruction analysis of 105 shoulder computed tomography scans.

BACKGROUND: The pathomechanisms of eccentric osteoarthritis of the shoulder remain unclear. Although there is increasing evidence of bony differences between shoulders with rotator cuff tears and osteoarthritis, analogous differences have not been identified for primary concentric and eccentric osteoarthritis. This study examined the shape and orientation of the acromial roof as a potential risk factor for the development of posterior glenoid wear. METHODS: We analyzed computed tomography images of 105 shoulders with primary osteoarthritis. Based on the classification of Walch, 45 shoulders had concentric osteoarthritis (Walch A) and 60 shoulders were affected by eccentric osteoarthritis (Walch B; EOA). A comparison of acromial morphology was performed in a multiplanar reconstruction analysis of computed tomography scans. RESULTS: Acromial shape: Acromial length, width, and area were not significantly different. Acromial roof orientation: The acromial roof in EOA was an average of 5° flatter (sagittal tilt; P < .01) and 5° more downward tilted (coronal tilt; P < .01). There was no difference in axial rotation (axial tilt; P = .47). Anteroposterior glenoid coverage: The glenoid in EOA was covered an average of 4° less posteriorly (P = .01) and 4° more anteriorly (P = .04). No differences were shown for overall glenoid coverage. CONCLUSIONS: The acromial roof could play a role in the pathogenesis of EOA. Less posterior support due to a flatter acromion with less posterior glenoid coverage could contribute to static posterior subluxation of the humeral head and posterior glenoid wear. Further biomechanical investigations are needed to confirm these findings.

Acromial roof in patients with concentric osteoarthritis and massive rotator cuff tears: multiplanar analysis of 115 computed tomography scans.

BACKGROUND: There is evidence for differences of scapular shape between shoulders with rotator cuff tears (RCT) and osteoarthritic shoulders (OA). This study analyzed orientation and shape of the acromion in patients with massive RCT and concentric OA (COA) in a multiplanar computed tomography (CT) analysis. METHODS: CT scans of 70 shoulders with degenerative RCT and 45 shoulders with COA undergoing primary shoulder arthroplasty were analyzed. The 2 groups were compared in relation of (1) shape of the acromion, (2) its orientation in space, and (3) the anteroposterior glenoid coverage in relation to the scapular plane. RESULTS: Lateral acromial roof extension was an average of 4.6 mm wider and the acromial area was an average of 156 mm2 larger in RCT than in COA (P < .001). Significant differences of the lateral extension of the acromion margin were limited to the anterior two-thirds. Acromial roof orientation in RCT was average of 10.8° more "externally rotated" (axial plane: P < .001) and an average of 7.8° more tilted downward (coronal plane: P < .001) than in COA. The glenoid in RCT was an average of 5.5° (P < .001) more covered posteriorly compared with COA. CONCLUSIONS: A more externally rotated (axial plane), more downward tilted (coronal plane), and wider posterior covering acromion was more frequent in patients with massive RCT than COA.