Biomechanical properties of a suture anchor system from human allogenic mineralized cortical bone matrix for rotator cuff repair.

BACKGROUND: Suture anchors (SAs) made of human allogenic mineralized cortical bone matrix are among the newest developments in orthopaedic and trauma surgery. Biomechanical properties of an allogenic mineralized suture anchor (AMSA) are not investigated until now. The primary objective was the biomechanical investigation of AMSA and comparing it to a metallic suture anchor (MSA) and a bioabsorbable suture anchor (BSA) placed at the greater tuberosity of the humeral head of cadaver humeri. Additionally, we assessed the biomechanical properties of the SAs with bone microarchitecture parameters. METHODS: First, bone microarchitecture of 12 fresh frozen human cadaver humeri from six donors was analyzed by high-resolution peripheral quantitative computed tomography. In total, 18 AMSAs, 9 MSAs, and 9 BSAs were implanted at a 60° angle. All three SA systems were systematically implanted alternating in three positions within the greater tuberosity (position 1: anterior, position 2: central, position 3: posterior) with a distance of 15 mm to each other. Biomechanical load to failure was measured in a uniaxial direction at 135°. RESULTS: Mean age of all specimens was 53.6 ± 9.1 years. For all bone microarchitecture measurements, linear regression slope estimates were negative which implies decreasing values with increasing age of specimens. Positioning of all three SA systems at the greater tuberosity was equally distributed (p = 0.827). Mean load to failure rates were higher for AMSA compared to MSA and BSA without reaching statistical significance between the groups (p = 0.427). Anchor displacement was comparable for all three SA systems, while there were significant differences regarding failure mode between all three SA systems (p < 0.001). Maximum load to failure was reached in all cases for AMSA, in 44.4% for MSA, and in 55.6% for BSA. Suture tear was observed in 55.6% for MSA and in 22.2% for BSA. Anchor breakage was solely seen for BSA (22.2%). No correlations were observed between bone microarchitecture parameters and load to failure rates of all three suture anchor systems. CONCLUSIONS: The AMSA showed promising biomechanical properties for initial fixation strength for RCR. Since reduced BMD is an important issue for patients with chronic rotator cuff lesions, the AMSA is an interesting alternative to MSA and BSA. Also, the AMSA could improve healing of the enthesis.

Implant-free iliac crest bone graft procedure shows anatomic remodelling without redislocation in recurrent anterior shoulder instability after short-term follow-up.

INTRODUCTION: With the help of a J-shaped bicortical iliac crest bone graft, the morphology of the glenoid can be augmented without having to use screws to achieve glenohumeral stability. The aim of this retrospective clinical study was to evaluate the clinical stability and function of the shoulder joint as well as the radiological remodelling process and arthropathic outcomes following the J-bone graft technique. MATERIALS AND METHODS: 34 patients with recurrent shoulder dislocations and bony glenoid defects were treated with the J-bone graft technique between 2010 and 2018 at our level-I trauma centre. 15 patients (18 shoulders) could be recruited for the study. Pain levels, ASES, UCLA, SST, DASH, Rowe and WOSI Scores were collected using questionnaires. In 13 patients (16 shoulders) the Constant Score, ROM, CT with 3D reconstruction of the glenoid to assess the graft remodelling and X-rays were performed additionally. RESULTS: None of the patients suffered subluxations or recurrent dislocations during the follow-up period. The overall complication rate was 11%. The evaluation using objective and subjective shoulder function scores yielded good-to-excellent results. Radiological assessment at follow-up showed a low rate of moderate-to-severe arthritis (12%) and a high rate of shoulders without any signs of arthritic degeneration (53%). The CT scans all revealed an almost complete restoration of the glenoid with none of the grafts being resorbed. A rise in the average glenoid circumference and glenoid area could be demonstrated between preoperative measurements (81.6 and 82.4%, respectively) and follow-up measurements (104 and 102.5%, respectively). CONCLUSION: The results of this study show a successful stabilisation of the shoulder joint and a low complication rate following the J-bone graft technique. Remodelling of the bone graft could be demonstrated, which in turn led to an almost perfect glenoid surface area of 100%.

Progression of function and pain relief as indicators for returning to sports after arthroscopic isolated type II SLAP repair-a prospective study.

BACKGROUND: One of the currently used surgical techniques in isolated type II SLAP lesions is arthroscopic SLAP repair. Postoperatively, patients tend to suffer from a prolonged period of pain and are restricted in their sports activities for at least 6 months. The aim of this study was to prospectively evaluate the clinical outcome as well as the postoperative course of pain after arthroscopic type II SLAP repair. METHODS: Outcome measures were assessed using the Individual Relative Constant Score (CSindiv), the American Shoulder and Elbow Surgeons (ASES) Score, the Visual Analogue Scale (VAS), and the Short Form 36 (SF-36). Data were collected preoperatively, as well as at 3, 6, 12 and >24 months postoperatively. RESULTS: Eleven patients with an average age of 31.8 years (range: 22.8-49.8 years) underwent arthroscopic repair of isolated type II SLAP lesions. Mean follow-up time was 41.9 months (range: 36.1-48.4 months). 6 months after surgery, there was a statistically significant improvement of function according to the CSindiv (p = 0.004), the ASES Score (p = 0.006), and the SF-36 subscale "physical functioning" (p = 0.014) and a statistically significant decrease of pain according to the VAS (p = 0.007) and the SF-36 subscale "bodily pain" (p = 0.022) compared to preoperative levels. CONCLUSIONS: Arthroscopic repair of isolated type II SLAP lesions with suture anchors leads to a satisfactory functional outcome and return to pre-injury sports levels, with delayed, but significant pain relief observed 6 months after surgery. Thus, a return to sports should not be allowed earlier than 6 months after surgery, when patients have reached pain-free function and recovered strength. TRIAL REGISTRATION: Researchregistry1761 (UIN).

Periprosthetic proximal humerus fractures require an individualized treatment approach-results of a multicenter retrospective study.

BACKGROUND: In the last years, there has been increasing use of shoulder arthroplasty. As a result, an increasing incidence of periprosthetic humerus fractures (PPHF) is expected. Therefore, this retrospective, multicenter analysis aimed to collect demographic data from patients with PPHF, their treatment strategies, and associated complications. METHODS: Demographics of patients with PPHF were collected retrospectively from the database of six trauma hospitals between January 2000 and December 2020. All fractures were categorized according to the Wright and Cofield, and Worland classifications. In addition, the type of treatment for PPHF, as well as subsequent complications, were evaluated. RESULTS: A total of 72 patients with a PPHF were identified. The mean age of the 55 female and 17 male patients was 77 years. PPHF occurred a mean of 50 months after primary arthroplasty implantation, almost exclusively as a result of a fall from standing height (n = 67). In-situ implant was a RTSA in 40 patients and a hemiarthroplasty in 32 patients. More than half of the fractures (n = 38) were type B fractures, according to Wright and Cofield. According to Worland, the majority of patients also had a type B fracture (type B1 (n = 22), type B2 (n = 28), type B3 (n = 10)). Associated comorbidities were found in 21 patients. A total of 31 patients were treated non-operatively, 27 with Open Reduction Internal Fixation (ORIF), and 14 with a revision arthroplasty. Nine primary radial nerve palsies were found (pre-operatively), and seven secondarily (post-operatively). Nine patients suffered from non-union (ORIF 4, non operative 4, stem replacement 1). CONCLUSION: The treatment strategy for PPHF is primarily tailored to the individual patient. Decisive factors such as patient's age, fracture type, and primary palsies have to be considered for optimal treatment. In type B1 fractures, there is a recommendation for ORIF because of high non-union rates under non-operative treatment. In contrast, in type B2 fractures, a non-operative approach should be preferred, provided there are no radial nerve lesions. LEVEL OF EVIDENCE: Level IV, epidemiologic study.

Continuously increasing e-scooter accidents and their possible prevention in a large European city.

PURPOSE: During the last few years, the number of electric scooter (e-scooter) users has risen to an all-time high. This study aimed to analyze e-scooter related accidents and trauma prevention measures in a large European city (Vienna, Austria). METHODS: This retrospective study comprises a thorough data assessment and analysis of all e-scooter related accidents between 2018 and 2021 at a large level 1 trauma center in Vienna. Based on the data analysis, risk factors were identified, and possible prevention strategies were proposed. RESULTS: During the observed period, 1337 patients sustained an injury from an e-scooter. Of these, 1230 were injured directly while driving (92%). The remaining 107 patients (8%) were classified as non-driving injuries. 927 injuries involved males (69.3%). The mean age was 32.1 years (range 4-86 years). Of all injured patients, 429 (32.1%) sustained at least one serious injury. The most common injuries included radial head fractures and concussions. Among the accidents treated, the use of protective equipment was sporadic. For example, helmets were worn in only 13.7% of cases. Wearing a helmet reduced the number of head injuries (24% versus 46.8%). In just three years, the number of patients increased 19-fold with a focus in the summer months. CONCLUSION: This study shows a substantial and sustained increase in e-scooter accidents with potentially serious injuries. Helmet use was found to be an effective form of head injury prevention. Further options for using protective equipment should be evaluated to improve the safety aspects of riding e-scooters.

Glenohumeral Pathologies following Primary Anterior Traumatic Shoulder Dislocation-Comparison of Magnetic Resonance Arthrography and Arthroscopy.

BACKGROUND: We assessed intraarticular injuries in patients after primary anterior traumatic shoulder dislocation by comparing magnetic resonance arthrography (MRA) results with concomitant arthroscopic findings. METHODS: All patients with primary traumatic shoulder dislocation who underwent arthroscopic surgery between 2001 and 2020 with preoperative MRA were included in this study. MRA was retrospectively compared with arthroscopic findings. Postoperative shoulder function was prospectively assessed using the Disabilities of Arm, Shoulder and Hand score (quick DASH), the Oxford Shoulder Score (OSS), the Subjective Shoulder Value (SSV), as well as the rate of return to sports. RESULTS: A total of 74 patients were included in this study. A Hill-Sachs lesion was consistently found in the corresponding shoulders on MRA and arthroscopy in 35 cases (p = 0.007), a Bankart lesion in 37 shoulders (p = 0.004), and a superior labrum from anterior to posterior (SLAP) lesion in 55 cases (p = 0.581). Of all cases, 32 patients were available for a clinical and functional follow-up evaluation. A positive correlation was found between the level of sport practiced and the Oxford Shoulder Score (redislocation subset) (p = 0.032) and between the age at the time of surgery and the follow-up SSV (p = 0.036). Conversely, a negative correlation was observed between the age at the time of surgery and the Oxford Instability Score (redislocation subset) (p = 0.038). CONCLUSIONS: The results of this study show a good correlation between MRA and arthroscopy. Therefore, MRA is a valid tool for the detection of soft tissue pathologies after primary anterior traumatic shoulder dislocation and can aid in presurgical planning.

High-energy extracorporeal shockwave therapy in humeral delayed and non-unions.

INTRODUCTION: Within the last few decades, focused high-energy extracorporeal shockwave therapy (ESWT) has proven to be an effective alternative to standard of care revision surgery in delayed healing fractures or manifest non-unions in various anatomical regions. MATERIALS AND METHODS: A retrospective multi-variant analysis of an open prospective, single-armed clinical study was conducted. Patients receiving focused high-energy ESWT for a delayed healing or an apparent non-union of a humeral fracture between January 1999 and December 2015 at a single trauma center were included in the study. Bony healing was defined as cortical continuity in three of four cortices and pain-free force loading and evaluated using CT scans and clinical examination at three- and six-month follow-ups after ESWT. RESULTS: A total of 236 patients were included. N = 93 (43.8%) showed bony consolidation three months after ESWT and n = 105 (52.5%) after six months. Sub-group analysis showed significantly better healing for the proximal metaphyseal humerus (66.7% after six months, n = 42) compared to the diaphyseal region (48.1%, n = 133) and distal metaphyseal humerus (48.1%, n = 25). Regression analysis indicated significantly increased healing rates for patients of younger ages (p = 0.001) and a fracture diastasis of less than 5 mm (p = 0.002). CONCLUSION: The findings of this study indicate that ESWT can be considered as a treatment option for a well-selected patient population despite the lower healing rates compared to other anatomical regions.

Associated Pathologies following Luxatio Erecta Humeri: A Retrospective Analysis of 38 Cases.

Inferior shoulder dislocation in fixed abduction, also known as luxatio erecta humeri (LEH), is a rare injury with little data available. Therefore, the primary aim of this study was to evaluate and present our case series of this type of injury with special emphasis on associated pathologies; the secondary aim was to present diagnostic recommendations to detect for potential associated pathologies typically seen with this injury. A total of 38 patients (13 females, average age 72.8 years and 25 males, average age 41.4 years), who have been treated for inferior shoulder dislocation between 1992 and 2020, were included in this study. Associated pathologies after LEH were found in 81% of the cases. Twenty-one of these patients presented with secondary bony pathologies. Six patients revealed rotator cuff injuries diagnosed by magnetic resonance imaging (MRI). Seven patients exhibited pathological findings at the capsule-ligament complex. Eight patients presented with neurological findings. All neurologic symptoms except one axillary nerve palsy and a radialis paresis dissolved during the follow-up period. Five patients received surgical treatment of the affected shoulder. Inferior shoulder dislocation is a rare condition presenting with a high number of associated injuries. According to the findings of the present study, we want to raised awareness of the high rate of potential secondary shoulder pathologies associated with LEH. Beside a thorough clinical examination and immediate standard radiographs in two planes, we recommend to perform computed tomography scanning and an MRI of the shoulder as soon as possible. In the case of neurologic deficiencies, a determination of nerve conduction should be performed.

Muscle-Specific Micro-Ribonucleic Acids miR-1-3p, miR-133a-3p, and miR-133b Reflect Muscle Regeneration After Single-Dose Zoledronic Acid Following Rotator Cuff Repair in a Rodent Chronic Defect Model.

BACKGROUND: Zoledronic acid improves bone microarchitecture and biomechanical properties after chronic rotator cuff repair (RCR) in rats. Besides the positive effects of zoledronic acid on bone mineral density and bone microarchitecture, bisphosphonates have positive effects on skeletal muscle function. PURPOSES/HYPOTHESIS: The purposes of this study were to (1) longitudinally evaluate circulating bone- and muscle-specific serum micro-ribonucleic acids (miRNAs) and (2) investigate supraspinatus muscle tissue after tenotomy and delayed RCR in a rat model. It was hypothesized that zoledronic acid would improve muscle regeneration after chronic RCR in rats. STUDY DESIGN: Controlled laboratory study. METHODS: A total of 34 male Sprague-Dawley rats underwent unilateral (left) supraspinatus tenotomy (time point 1) with delayed transosseous RCR after 3 weeks (time point 2). All rats were sacrificed 8 weeks after RCR (time point 3). Animals were randomly assigned to 2 groups. One day after RCR, the control group was given 1 mL of subcutaneous saline solution, and the intervention group was treated with a subcutaneous single-dose of 100 µg/kg body weight of zoledronic acid. All 34 study animals underwent miRNA analysis at all 3 time points. In 4 animals of each group, histological analyses as well as gene expression analyses were conducted. RESULTS: Circulating miRNAs showed significantly different expressions between both study groups. In the control group, a significant downregulation was observed for muscle-specific miR-1-3p (P = .004), miR-133a-3p (P < .001), and miR-133b (P < .001). Histological analyses showed significantly higher rates of regenerating myofibers on the operated side (left) of both study groups compared with the nonoperated side (right; P = .002). On the nonoperated side, significantly higher rates of regenerating myofibers were observed in the intervention group compared with the control group (P = .031). The myofiber cross-sectional area revealed significantly smaller myofibers on both sides within the intervention group compared with both sides of the control group (P < .001). Within the intervention group, significantly higher expression levels of muscle development/regeneration marker genes embryonal Myosin heavy chain (P = .017) and neonatal Myosin heavy chain (P = .016) were observed on the nonoperated side compared with the operated side. CONCLUSION: An adjuvant single-dose of zoledronic acid after RCR in a chronic defect model in rats led to significant differences in bone- and muscle-specific miRNA levels. Therefore, miR-1-3p, miR-133a-3p, and miR-133b might be used as biomarkers for muscle regeneration after RCR. CLINICAL RELEVANCE: Adjuvant treatment with zoledronic acid may improve muscle regeneration after chronic RCR in humans, thus counteracting fatty muscle infiltration and atrophy.

Improved biomechanics in experimental chronic rotator cuff repair after shockwaves is not reflected by bone microarchitecture.

PURPOSE: The aim of this study was to investigate the effect of extracorporeal shockwave therapy (ESWT) on bone microstructure as well as the bone-tendon-interface and the musculo-tendinous transition zone to explain the previously shown improved biomechanics in a degenerative rotator cuff tear animal model. This study hypothesized that biomechanical improvements related to ESWT are a result of improved bone microstructure and muscle tendon properties. METHODS: In this controlled laboratory study unilateral supraspinatus (SSP) tendon detachment was performed in 48 male Sprague-Dawley rats. After a degeneration period of three weeks, SSP tendon was reconstructed transosseously. Rats were randomly assigned into three groups (n = 16 per group): control (noSW); intraoperative shockwave treatment (IntraSW); intra- and postoperative shockwave treatment (IntraPostSW). Eight weeks after SSP repair, all rats were sacrificed and underwent bone microstructure analysis as well as histological and immunohistochemical analyses. RESULTS: With exception of cortical porosity at the tendon area, bone microstructure analyses revealed no significant differences between the three study groups regarding cortical and trabecular bone parameters. Cortical Porosity at the Tendon Area was lowest in the IntraPostSW (p≤0.05) group. Histological analyses showed well-regenerated muscle and tendon structures in all groups. Immunohistochemistry detected augmented angiogenesis at the musculo-tendinous transition zone in both shockwave groups indicated by CD31 positive stained blood vessels. CONCLUSION: In conclusion, bone microarchitecture changes are not responsible for previously described improved biomechanical results after shockwave treatment in rotator cuff repair in rodents. Immunohistochemical analysis showed neovascularization at the musculo-tendinous transition zone within ESWT-treated animals. Further studies focusing on neovascularization at the musculo-tendinous transition zone are necessary to explain the enhanced biomechanical and functional properties observed previously. CLINICAL RELEVANCE: In patients treated with a double-row SSP tendon repair, an improvement in healing through ESWT, especially in this area, could prevent a failure of the medial row, which is considered a constantly observed tear pattern.

Physeal injuries of the proximal humerus: long-term results in seventy two patients.

PURPOSE: The aim of this study was to evaluate our treatment methods of proximal humeral physeal injuries retrospectively and elucidate the relationship between the trauma mechanism, the radiographic injury pattern, the consequent therapy and the functional outcome, and to further deduct and verify prognostic criteria. METHODS: At our Department of Trauma Surgery, 303 children and adolescent patients with fractures of the proximal humeral epiphysis were treated from 1992 to 2009. 72 cases were diagnosed as physeal fractures according to the Salter-Harris classification and were included in our study. RESULTS: 15 physeal fractures of the proximal humerus were reconstructed anatomically by open or closed reduction and produced 93.3% excellent results. 57 physeal fractures were treated in a conservative way and produced 94.7% excellent results. CONCLUSION: We state that epiphyseal injuries should to be treated depending on the age of the patient. This is the only way to decrease the rate of posttraumatic epiphysiodesis with consequent problems, including limb-length discrepancy and/or angular deformities.

Complication rate after operative treatment of three- and four-part fractures of the proximal humerus: locking plate osteosynthesis versus proximal humeral nail.

PURPOSE: There is still disagreement regarding the optimal surgical treatment of three- and four-part fractures of the proximal humerus. The aim of this monocentric, retrospective study was to compare the complication rate of internal fixation with a locking plate versus proximal humeral nailing after a one-year follow-up. METHODS: From 2005 to 2016, 292 patients suffered a fracture of the proximal humerus and were treated surgically at our level-I trauma center. According to the inclusion criteria, 50 patients were included in this study: 19 of these (11 three-part fractures and 8 four-part fractures) were treated with a proximal humeral nail (HN) and 31 (12 three-part fractures and 19 four-part fractures) with a locking plate (LP) osteosynthesis. Classification was performed according to the Hertel classification. At a 1-year follow-up, the complication rate of the two treatment methods was compared. RESULTS: Twenty patients (40%) suffered at least one complication. Of these, six patients (12%) were treated with a HN and 14 (28%) with a LP (p = 0.39). The most frequent complication was screw perforation (22%), followed by non-union (16%). Humeral head necrosis (10%) occurred only in the LP cohort. One wound infection occurred in a patient treated with a HN. Four-part fractures were treated more frequently with a LP. However, the difference was non-significant in this sample (p = 0.186). CONCLUSIONS: The results of our study provide some evidence that in terms of complication rate, both treatment options are comparable for internal fixation of three- and four-part fractures of the proximal humerus. The type of fracture seems to be decisive for the choice of implant.

Lugol's solution but not formaldehyde affects bone microstructure and bone mineral density parameters at the insertion site of the rotator cuff in rats.

BACKGROUND: This study aimed to investigate whether rodent shoulder specimens fixed in formaldehyde for histological and histomorphometric investigations and specimens stained using Lugol's solution for soft tissue visualization by micro-computed tomography (microCT) are still eligible to be used for bone architecture analysis by microCT. METHODS: In this controlled laboratory study, 11 male Sprague-Dawley rats were used. After sacrifice and exarticulation both shoulders of healthy rats were assigned into three groups: (A) control group (n = 2); (B) formaldehyde group (n = 4); (C) Lugol group (n = 5). Half of the specimens of groups B and C were placed in a 4% buffered formaldehyde or Lugol's solution for 24 h, whereas the contralateral sides and all specimens of group A were stored without any additives. MicroCT of both sides performed in all specimens focused on bone mineral density (BMD) and bone microstructure parameters. RESULTS: BMD measurements revealed higher values in specimens after placement in Lugol's solution (p < 0.05). Bone microstructure analyses showed increased BV/TV and Tb.Th values in group C (p < 0.05). Specimens of group C resulted in clearly decreased Tb.Sp values (p < 0.05) in comparison to the control group. Formaldehyde fixation showed minimally altered BMD and bone microstructure measurements without reaching any significance. CONCLUSIONS: MicroCT scans of bone structures are recommended to be conducted natively and immediately after euthanizing rats. MicroCT scans of formaldehyde-fixed specimens must be performed with caution due to a possible slight shift of absolute values of BMD and bone microstructure. Bone analysis of specimens stained by Lugol's solution cannot be recommended.

Fracture patterns in patients with multiple fractures: the probability of multiple fractures and the most frequently associated regions.

INTRODUCTION: Multiple fractures are of high clinical relevance, as a significant increase in mortality rate has been described. The purpose of this study was to evaluate differences in age and gender distribution in multiple fractures dependent on severity of trauma. Furthermore, affected anatomic regions and frequently associated fracture regions were investigated. METHODS: Patients who had sustained multiple fractures between 2000 and 2012 were included in this study. At hospital admission, patients were divided according to trauma severity (high- vs low-traumatic), gender, and age for demographic analysis. Fractures were grouped in anatomical regions, and multiple fracture event probabilities as well as frequently associated regions were calculated. RESULTS: In total, 25,043 patients at an age range of 0-100 years (5.8% of all fracture patients; 14,769 male and 10,274 female patients) who sustained 57,862 multiple fractures were included. The lumbar/thoracic spine, cervical spine, femoral shaft, skull, and pelvis showed a probability of more than 40% of the presence of further fractures in each high-traumatic fracture event. In high-traumatic fracture events, male patients were more affected (p < 0.001). Considering low-traumatic fractures, female patients had a significantly higher proportion (p < 0.001) of multiple fractures among all fractures than male patients. CONCLUSIONS: As a novelty, gender as well as age distributions in multiple fracture patients and a probability statement with the most affected anatomic regions, the risk of presence of further fractures for every region, and the frequently associated fracture regions including the percentage of occurrence are provided. These aspects yield new opportunities for clinical work and may reduce the high rate of overlooked fractures stated in the literature.

Zoledronic Acid Substantially Improves Bone Microarchitecture and Biomechanical Properties After Rotator Cuff Repair in a Rodent Chronic Defect Model.

BACKGROUND: Bone mineral density at the humeral head is reduced in patients with chronic rotator cuff tears. Bone loss in the humeral head is associated with repair failure after rotator cuff reconstruction. Bisphosphonates (eg, zoledronic acid) increase bone mineral density. HYPOTHESIS: Zoledronic acid improves bone mineral density of the humeral head and biomechanical properties of the enthesis after reconstruction of chronic rotator cuff tears in rats. STUDY DESIGN: Controlled laboratory study. METHODS: A total of 32 male Sprague-Dawley rats underwent unilateral (left) supraspinatus tenotomy with delayed transosseous rotator cuff reconstruction after 3 weeks. All rats were sacrificed 8 weeks after rotator cuff repair. Animals were randomly assigned to 1 of 2 groups. At 1 day after rotator cuff reconstruction, the intervention group was treated with a single subcutaneous dose of zoledronic acid at 100 µg/kg bodyweight, and the control group received 1 mL of subcutaneous saline solution. In 12 animals of each group, micro-computed tomography scans of both shoulders were performed as well as biomechanical testing of the supraspinatus enthesis of both sides. In 4 animals of each group, histological analyses were conducted. RESULTS: In the intervention group, bone volume fraction (bone volume/total volume [BV/TV]) of the operated side was higher at the lateral humeral head (P = .005) and the medial humeral head (P = .010) compared with the control group. Trabecular number on the operated side was higher at the lateral humeral head (P = .004) and the medial humeral head (P = .001) in the intervention group. Maximum load to failure rates on the operated side were higher in the intervention group (P < .001). Cortical thickness positively correlated with higher maximum load to failure rates in the intervention group (r = 0.69; P = .026). Histological assessment revealed increased bone formation in the intervention group. CONCLUSION: Single-dose therapy of zoledronic acid provided an improvement of bone microarchitecture at the humeral head as well as an increase of maximum load to failure rates after transosseous reconstruction of chronic rotator cuff lesions in rats. CLINICAL RELEVANCE: Zoledronic acid improves bone microarchitecture as well as biomechanical properties after reconstruction of chronic rotator cuff tears in rodents. These results need to be verified in clinical investigations.

Angular stable fixation of proximal humeral fractures.

BACKGROUND: Proximal humeral fractures requiring surgical stabilization remain a therapeutic challenge. High rates of treatment-related complications have been reported to be associated, particularly in elderly patients with unstable fracture types and diminished bone quality. In recent years, angular stable implants have been introduced to improve the patients' outcome. The purpose of this study was to assess the clinical and radiographic long-term results after angular stable plate fixation of proximal humeral fractures at this Level I trauma center, with special emphasis on fracture healing, functional outcome and treatment related complications. METHODS: We retrospectively analyzed functional and radiographic results of 42 patients (average age: 57.8 years) after angular stable plate fixation of proximal humeral fractures at an average time of 3.2 (+/-0.8) years after trauma. Functional results were defined by the Constant shoulder score (CS) and the individual Constant score (CSindiv). Radiographic results were assessed by a three-view trauma series (anteroposterior, lateral, and axillary view). For operative treatment, two different angular stable implants were used. Twenty-seven patients were stabilized by a HOFER plate, fifteen patients by a Locking Proximal Humerus Plate. RESULTS: Clinical results revealed an average CS of 74.0 points and an average individual CSindiv of 79.2% points. Fourteen patients had an excellent functional outcome, eight patients a good outcome and fourteen patients had moderate functional results. Six patients (14%) had a poor outcome with less than 55% on CSindiv. Regarding the radiographic outcome, we had an overall union rate of 95% (40 of 42). Failures of reduction and fixation occurred in fourteen patients (33%), and in nine patients (21%) we had signs of a humeral head necrosis. Re-operation due to treatment-related complications was necessary in two patients (5%). Statistical analysis revealed that the fracture type and the age of the patients had a significant influence on the clinical outcome and on the incidence of treatment-related complications. CONCLUSION: With regards to fracture healing and functional outcome of the patients, we had a satisfactory outcome after angular stable plate fixation of proximal humeral fractures. However, we experienced a notably high rate of technical failures and partial humeral head necrosis. Advanced surgical skills and experiences are necessary to achieve correct anatomic reduction and implant fixation, to reduce the risk of these treatment-related complications.

Molecular Pattern and Density of Axons in the Long Head of the Biceps Tendon and the Superior Labrum.

The type II superior labrum anterior to posterior (SLAP) repair is a viable option in young and demanding patients, although a prolonged period of pain after surgery is described in the literature. The reason for this fact remains unknown. Thus, the purpose of this study was to investigate the molecular pattern of the biceps tendon anchor, where the sutures for repair are placed. The long head of the biceps tendon (LHBT), including the superior labrum, was dissected in the setting of reverse total shoulder arthroplasty. Immunohistochemical staining was performed using neurofilament (NF) and protein gene product (PGP) 9.5 as general markers for axons and calcitonin gene-related peptide (CGRP) and substance P for nociceptive transmission. A quantitative assessment was performed according to the two regions of interest (ROIs), i.e., the anterosuperior (ROI I) and the posterosuperior labrum (ROI II). Eleven LHBTs with a mean age of 73 years (range: 66-87 years) were harvested intraoperatively. Six LHBTs were gained in osteoarthrosis and five in fractures. We found an inhomogeneous distribution of axons in the anterosuperior and posterosuperior parts of the labrum in all the specimens irrespective of the age, gender, and baseline situation. There was a significantly higher number (p < 0.01) as well as density (p < 0.001) of NF-positive axons in ROI I compared to ROI II. Nociceptive fibers were always found along the NF-positive axons. Thus, our results indicate that the biceps tendon anchor itself is a highly innervated region comprising different nerve qualities. The anterosuperior labrum contains a higher absolute number and density of axons compared to the posterosuperior parts. Furthermore, we were able to prove the presence of nociceptive fibers in the superior labrum. The results obtained in this study could contribute to the variability of pain after SLAP repair.

Substantial Biomechanical Improvement by Extracorporeal Shockwave Therapy After Surgical Repair of Rodent Chronic Rotator Cuff Tears.

BACKGROUND: Characteristics of chronic rotator cuff tears include continuous loss of tendon structure as well as tendon elasticity, followed by a high failure rate after surgical reconstruction. Several studies have already shown the beneficial effect of extracorporeal shockwave therapy (ESWT) on tissue regeneration in tendon pathologies. HYPOTHESIS: ESWT improves biomechanical tendon properties as well as functional shoulder outcomes in chronic rotator cuff reconstruction in rodents. STUDY DESIGN: Controlled laboratory study. METHODS: After tendon detachment and 3 weeks of degeneration, a subsequent transosseous reattachment of the supraspinatus tendon was performed in 48 adult male Sprague-Dawley rats (n = 16 per group). Rodents were randomly assigned to 3 study groups: no ESWT/control group, intraoperative ESWT (IntraESWT), and intra- and postoperative ESWT (IntraPostESWT). Shoulder joint function, as determined by gait analysis, was assessed repeatedly during the observation period. Eight weeks after tendon reconstruction, the rats were euthanized, and biomechanical and gene expression analyses were performed. RESULTS: Macroscopically, all repairs were intact at the time of euthanasia, with no ruptures detectable. Biomechanical analyses showed significantly improved load-to-failure testing results in both ESWT groups in comparison with the control group (control, 0.629; IntraESWT, 1.102; IntraPostESWT, 0.924; IntraESWT vs control, P≤ .001; IntraPostESWT vs control, P≤ .05). Furthermore, functional gait analyses showed a significant enhancement in intensity measurements for the IntraPostESWT group in comparison with the control group (P≤ .05). Gene expression analysis revealed no significant differences among the 3 groups. CONCLUSION: Clearly improved biomechanical results were shown in the single-application and repetitive ESWT groups. Furthermore, functional evaluation showed significantly improved intensity measurements for the repetitive ESWT group. CLINICAL RELEVANCE: This study underpins a new additional treatment possibility to prevent healing failure. Improved biomechanical stability and functionality may enable faster remobilization as well as an accelerated return to work and sports activities. Furthermore, as shockwave therapy is a noninvasive, easy-to-perform, cost-effective treatment tool with no undesired side effects, this study is of high clinical relevance in orthopaedic surgery. Based on these study results, a clinical study has already been initiated to clinically confirm the improved functionality by ESWT.

Bone Stress Injuries Are Associated With Differences in Bone Microarchitecture in Male Professional Soldiers.

Bone stress injuries are commonly due to repetitive loading, as often described in competitive athletes or military recruits. The underlying pathophysiology of bone stress injuries is multifactorial. The present cross-sectional study investigated (i) cortical and trabecular bone microstructure as well as volumetric bone mineral density in subjects with bone stress injuries at the tibial diaphysis, measured at the distal tibia and the distal radius by means of high-resolution peripheral quantitative computed tomography (CT), (ii) areal bone mineral density using dual-energy X-ray absorptiometry as well as calcaneal dual X-ray absorptiometry and laser, and (iii) the influence on bone turnover markers of formation and resorption at the early phase after injury. A total of 26 Caucasian male professional soldiers with post-training bone stress injury at the tibial diaphysis were included (case group). A total of 50 male, Caucasian professional soldiers from the same military institution served as controls (control group). High-resolution peripheral quantitative CT revealed a higher total area at the radius within the case group. Cortical bone mineral density was reduced at the radius and tibia within the case group. The trabecular number and trabecular thickness were reduced at the tibia in the case group. The trabecular network was more inhomogeneous at the radius and tibia within the case group. Calcaneal dual X-ray absorptiometry and laser was significantly reduced in the case group. This study quantified differences in bone microstructure among otherwise healthy individuals. Differences in bone microarchitecture may impair the biomechanical properties by increasing the susceptibility to sustain bone stress injuries. © 2019 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 37:2516-2523, 2019.