How does a varus deformity of the humeral head affect elevation forces and shoulder function? A biomechanical study with human shoulder specimens

Assessment of fracture stability following modified minimally invasive reduction osteosynthesis system (MIROS) fixation for Neer 2 and 3-Part proximal humeral fractures

BACKGROUND

Conservative management for elderly proximal humeral fractures is an acceptable option, but the fracture stability is dubious. The purpose of this study was to investigate fracture stability and functional outcomes after modified minimally invasive reduction osteosynthesis system (MIROS) and non-surgical treatment for Neer two and three-part proximal humeral fractures in elderly patients.

METHODS

Elderly Patients with two and three-part proximal humeral fractures who underwent modified MIROS fixation and non-operative management were retrospectively included. The Constant-Murley score, and the range of shoulder forward elevation were measured for functional assessment, while the radiological humeral head height (HHH) and humeral shaft angle (HSA) were used to verify the fracture stability. The variables in both treatment groups were compared using a two-tailed t test for independent means, with a p value of less than 0.05 denoting a significant difference.

RESULTS

Forty-two patients were consecutively included, with a mean follow-up of 24.05 ± 3.9 months for the modified MIROS group and 24.67 ± 4.5 months for the non-operative group. The modified MIROS group had statistically significant improvements in the Constant score and shoulder forward flexion (p = 0.0001), with a lower complication rate (14.3% vs. 52.3%). Moreover, the average changes in the radiological HSA and HHH were lower in the modified MIROS group at the one-year follow-up (p = 0.00001).

CONCLUSIONS

Modified MIROS is recommended as an alternative to conservative treatment for Neer 2 and 3-part proximal humeral fractures in elderly, medically unfit patients. It is a minimally invasive procedure that provides adequate fracture stability and permits early shoulder motion, with satisfactory functional and radiologic outcomes and fewer complications.

LEVEL OF EVIDENCE

Retrospective comparative cohort; level of evidence (III).

The Clinical and Radiological Outcomes and Complications of Bilboquet Implant for Proximal Humerus Fractures: A Systematic Review

Background/Objectives: There is no consensus in the literature regarding the optimal treatment for complex proximal humerus fractures (PHFs). The aim of this study is to evaluate the clinical, functional, and radiological outcomes, and complications, associated with the Bilboquet implant in the treatment of PHFs. Methods: The search was conducted from the first description of the Bilboquet device in 1994 to June 2024, across PubMed, Web of Science, and Google Scholar, using specific keywords such as ("Bilboquet" OR "Bilboquet prosthesis" OR "Bilboquet device") AND ("proximal humerus fracture" OR "shoulder fracture"), along with Boolean operators. The inclusion criteria comprised studies published in English or French that focused on the use of the Bilboquet implant for PHFs. Eligible study designs included case series, cohort studies, randomized controlled trials (RCTs), and non-RCTs evaluating clinical, functional, and radiological outcomes, and complications. Studies that do not contain relevant results to this systematic review, pediatric populations, or the use of alternative implants were excluded. Results: A total of eight studies (235 patients) published between 1996 and 2021 were included. The mean age was 68.6 years (56 to 76.8) in all the studies. The majority of patients, 76.2%, were females, with male patients accounting for only 23.8%. A total of 10 (4.3%) patients had 2-part fractures, 40% of patients had 3-part fractures, and 55.7% of patients had 4-part fractures. The mean follow-up was 36.4 months (25.8-88.7), with a mean constant score of 69.7 (62-78.6). Complications included non-union in 2.65% of cases, avascular necrosis in 19.7%, revision surgery in 5.1%, and protrusion of the staple in 4.3%. Conclusions: Despite limited knowledge of the Bilboquet implant, it shows promise in managing complex PHFs in both young and older adults, with favorable clinical and radiological outcomes. It offers advantages over traditional fixation methods and allows easy conversion to arthroplasty if osteonecrosis occurs. However, the long-term outcomes require further study. While early results are promising, larger randomized studies are needed to confirm its broader clinical utility.

A severe case of bilateral humerus varus deformity from the Middle Bronze age necropolis of Olmo di Nogara, Northeast Italy. The contribution of biomechanical analysis to paleopathological study

OBJECTIVE

To gain insights on possible impairment of a Middle Bronze Age individual with bilateral humerus varus buried with a sword in Northeastern Italy.

MATERIALS

A skeleton of a 40-50-year-old male from Olmo di Nogara (Italy) compared to other males from the same necropolis and to Neolithic and Iron Age samples from Italy.

METHODS

Macroscopic/X-rays analysis for pathological diagnosis and cross-sectional geometric analysis.

RESULTS

Both humeri of the individual appear short with destruction of the humeral heads, showing severe osteoarthrosis and flattening of the scapular glenoid cavities. The individual showed appreciable humeral bilateral asymmetry; there is no evidence for sustained immobilization.

CONCLUSIONS

The pathological modifications suggest a diagnosis of bilateral humeral varism probably following an injury at birth. The individual's life was likely not significantly affected, as evidence suggests that he remained active and possibly used weapons.

SIGNIFICANCE

Biomechanical analyses provided a useful tool to reconstruct the life of the subject within the community, showing that this individual's apparent upper limb abnormalities did not exempt him from a role as a warrior and highlighting the importance of the warrior identity in this Bronze Age society.

LIMITATIONS

The complex interaction between epiphyseal damage and shortening of the humerus makes it difficult to assess activity patterns. Only severe impairment leading to long-term immobilization can be excluded for this individual.

SUGGESTIONS FOR FURTHER RESEARCH

Cross-sectional geometry may be used in other cases of humerus varus or bone dysplasia to investigate functional impairment.

Pectoralis major pedicle bone grafting vs. tricortical iliac grafting for Neer 4-part proximal humerus fractures: a randomized controlled trial

BACKGROUND

The risk of avascular necrosis, nonunion, or malunion is high in osteoporosis-related 4-part fractures. We evaluated the results of patients who underwent plate osteosynthesis with a vascularized pectoralis major graft compared with tricortical iliac grafting to treat 4-part proximal humerus fractures.

MATERIAL AND METHODS

Thirty-four patients aged 50-75 years with Neer 4-part proximal humerus fractures were studied. Group A (n = 17) underwent osteotomy of a 2.5 ± 1 cm pectoralis major pedicle bone graft and plate application, whereas group B (n = 17) underwent plate osteosynthesis using iliac autogenous grafts. Final follow-up assessments included evaluation using Constant and American Shoulder and Elbow Surgeons scoring systems, humeral neck-shaft angle (HNSA), humeral head height, and humeral head avascular necrosis.

RESULTS

Reduction loss was observed in 3 patients (17.6%) in group A, whereas it was observed in 10 patients (58.8%) in group B (P = .013). Humeral head avascular necrosis was found in 1 patient (5.8%) in group A, whereas it was found in 5 patients (29.4%) in the other group (P = .071). The HNSA was normal in 12 (70.5%) of group A patients, whereas it was normal in 6 (35.2%) of group B patients. The HNSA was weak or bad (<1200) in 29.4% of group A patients, whereas this rate was 64.7% in group B patients. Humeral head height was 2.64 ± 1.45 mm in group A and 3.66 ± 1.65 mm in group B. There were no statistically significant differences between the 2 groups in terms of Constant and American Shoulder and Elbow Surgeons scoring systems.

CONCLUSION

Pectoralis major bone pedicle graft in Neer 4-part proximal humerus fractures reduces the risk of avascular necrosis and nonunion rates. Our technique yielded excellent clinical and radiological results. We achieved recovery without creating additional donor site morbidity.

Influence of preoperative simulation on the reduction quality and clinical outcomes of open reduction and internal fixation for complex proximal humerus fractures

PURPOSE

Proximal humerus fractures (PHFs) are common. With the development of locking plates, open reduction and internal fixation (ORIF) of the proximal humerus can provide excellent clinical outcomes. The quality of fracture reduction is crucial in the locking plate fixation of proximal humeral fractures. The purpose of this study was to determine the impact of 3-dimensional (3D) printing technology and computer virtual technology assisted preoperative simulation on the reduction quality and clinical outcomes of 3-part and 4-part proximal humeral fractures.

METHOD

A retrospective comparative analysis of 3-part and 4-part PHFs undergoing open reduction internal fixation was performed. Patients were divided into 2 groups according to whether computer virtual technology and 3D printed technology were used for preoperative simulation: the simulation group and the conventional group. Operative time, intraoperative bleeding, hospital stay, quality of fracture reduction, Constant scores, American Society for Shoulder and Elbow Surgery (ASES) scores, shoulder range of motion, complications, and revision surgeries were assessed.

RESULTS

This study included 67 patients (58.3%) in the conventional group and 48 patients (41.7%) in the simulation group. The patient demographics and fracture characteristics were comparable in these groups. Compared with the conventional group, the simulation group had shorter operation time and less intraoperative bleeding (P < 0.001, both). Immediate postoperative assessment of fracture reduction showed a higher incidence of greater tuberosity cranialization of < 5 mm, neck-shaft angle of 120° to 150°, and head shaft displacement of < 5 mm in the simulation group. The incidence of good reduction was 2.6 times higher in the simulation group than in the conventional group (95% CI, 1.2-5.8). At the final follow-up, the chance of forward flexion > 120° (OR 5.8, 95% CI 1.8-18.0) and mean constant score of > 65 (OR 3.4, 95% CI 1.5-7.4) was higher in the simulation group than the conventional group, as well as a lower incidence of complications in the simulation group was obtained (OR 0.2, 95% CI 0.1-0.6).

CONCLUSIONS

This study identified that preoperative simulation assisted by computer virtual technology and 3D printed technology can improve reduction quality and clinical outcomes in treatment of 3-part and 4-part PHFs.

Evaluation of mushroom-shaped allograft for unstable proximal humerus fractures

INTRODUCTION

Proximal humerus fractures are common injuries of the elderly. Different treatment options, depending on fracture complexity and stability, have been recommended in the literature. Particularly for varus displaced fractures with a lack of medial support, and patients suffering from osteoporosis, structural allografts can be used to enhance the stability of the construct. An individually shaped allograft has been suggested in the literature and investigated in a clinical setting. However, biomechanical properties have yet to be evaluated.

MATERIALS AND METHODS

Twenty-four fresh-frozen humeri and 12 femoral heads were obtained, and an unstable three-part fracture of the humeral head was simulated. Fracture fixation was achieved by using a locking plate in both groups. In the test group, a mushroom-shaped allograft was tailored out of a femoral head to individually fit the void inside the humeral head. Specimens were fitted with a 3D motion analysis system and cyclically loaded with a stepwise increasing load magnitude in a varus-valgus bending test until failure or up to a maximum of 10,000 load cycles.

RESULTS

The mushroom group reached a significantly higher number of load cycles (8342; SD 1,902; CI 7133-9550) compared to the control group (3475; SD 1488; CI 2530-4420; p < 0.001). Additionally, the test group showed significantly higher stiffness values concerning all observational points (p < 0.001).

CONCLUSION

This mushroom-shaped allograft in combination with a locking plate significantly increased load to failure as well as stiffness of the construct when exposed to varus-valgus bending forces. Therefore, it might be a viable option for surgical treatment of unstable and varus displaced proximal humerus fractures to superiorly prevent loss of reduction and varus collapse.

The forgotten fragment: additional lesser tuberosity fixation of 4-part proximal humeral fractures-a biomechanical investigation

BACKGROUND

Fractures of the proximal humerus are common. The most frequent surgical treatment option is open reduction and locking plate fixation. Multifragmentary fractures, including 3- and 4-part fractures, are especially challenging to treat because they correlate with an increased risk of fixation failure. In the past, several mechanisms of additional fixation were investigated, but none directly addressed the lesser tuberosity (LT). The goal of this study was to investigate the biomechanical impact of additional anterior fracture fixation in lateral locked plating (LLP) of 4-part proximal humeral fractures (PHFs).

METHODS

Twenty-seven fresh frozen human shoulder specimens (mean age, 80 years) with intact rotator cuffs (RCs) were randomized into 4 groups: 3-part PHF with LLP and RC cerclage (n = 6); 4-part PHF with LLP and RC cerclage as standard of care (n = 7); 4-part PHF with LLP, RC cerclage, and 2 anterior 3.5-mm cortical screws (n = 7); and 4-part PHF with LLP, RC cerclage, and additional anterior one-third tubular plate (additional anterior plating [AAP], n = 7). Static load of the RC was simulated with weights. A force-controlled cyclic loading test was performed with a servo-hydraulic testing machine, followed by load-to-failure testing. An optical motion capture system recorded humeral head range of motion.

RESULTS

LLP of a 4-part PHF showed more humeral head motion than LLP of a 3-part PHF without fracture of the LT (P < .001). Fixing the LT to the humeral head with two 3.5-mm screws significantly reduced humeral head motion compared with LLP with RC cerclage alone (P < .006). Using AAP significantly increased the construct stiffness compared with the standard of care (P = .03).

CONCLUSION

LLP of a 4-part PHF is biomechanically less stable than LLP of a 3-part PHF without fracture of the LT. Additional screw fixation of the LT in 4-part PHFs improves stability compared with LLP alone. In case of metaphyseal comminution, AAP is favorable from a biomechanical perspective.

Varus malposition relates to functional outcomes following open reduction and internal fixation for proximal humeral fractures: A retrospective comparative cohort study with minimum 2 years follow-up

BACKGROUND

The aim of this study was to evaluate functional outcomes in patients with varus malposition following open reduction and internal fixation of displaced proximal humeral fractures.

METHODS

Data of 685 patients with a mean age of 67±15.8 years (67% female), that were treated by open reduction and internal fixation for a displaced proximal humeral fracture at a level 1 trauma center, were analyzed. On standardized x-ray imaging, the degree of varus displacement was measured over a minimum of two years follow-up and patients were divided into three groups. Group A: anatomic or <10° of varus or valgus malposition, group B: 10-20° of varus malposition and group C: >20° varus malposition, while anatomic head-shaft-angle was defined 135° The groups were compared with regards to functional outcomes by means of the Constant Score (CS).

RESULTS

In 565 patients with anatomic to minor <10° varus or valgus malposition (Group A), the mean CS was 72.5 ± 18.8 points. The %CS to the uninjured side was 87.2 ± 24.1 and the age and gender normalized nCS was 84.7 ± 21.7. In comparison, in group B (10-20° varus) the mean CS was 64.7 ± 16.9, the mean %CS was 84.5 ± 18.3 and the mean nCS was 76.2 ± 20.6. In group C (>20° varus) the mean CS was 54.1 ± 19.5, the mean was %CS: 72.3 ± 26.4 and the mean nCS was 64.8 ± 23.8 (p = 0.02, p = 0.03, p = 0.01). Overall, the CS, %CS and nCS correlated significantly with the degree of varus position (Pearson correlation, r = 0.23, r = 0.21, r = 0.25).

CONCLUSION

Varus malposition is related to inferior functional outcomes compared to anatomic healing in patients treated by open reduction and internal fixation for proximal humeral fractures. The data supports suggestions to prevent varus malposition in open reduction and internal fixation. In severe >20° of varus malposition, revision surgery should be considered.

The incidence of occult and missed surgical neck fractures in patients with isolated greater tuberosity fracture of the proximal humerus

Background

Occult and missed surgical neck fractures can be found in patients diagnosed with isolated greater tuberosity (GT) fracture during the follow up period. The purpose of this study was to retrospectively assess the incidence rate of occult and missed surgical neck fractures in those initially diagnosed with isolated GT fracture.

Methods

Records of patients diagnosed as having an isolated GT fracture were retrieved from a database in a medical center. Two senior orthopedic surgeons blindly reviewed all images of these patients three times to classify GT fracture types (split, avulsion and depression types), and recorded any surgical neck fractures found. Then a meeting was help to confirm the fracture types and presence of surgical neck fracture.

Results

Occult surgical neck fractures were found in 5 out of 68 (7.4%) patients, whereas missed surgical neck fractures were found in 3 out of 68 (4.4%) patients. In total, 32 patients had split type GT fracture, 32 had avulsion type and 4 had depression type. For those with occult surgical neck fractures, 7 had the split type GT fracture, while the remaining one had the avulsion type. Although the proportion of occult surgical neck fracture was higher in the split-type GT fracture (21.9%) than in the avulsion-type GT fracture (3.1%), the difference was not statistically significant (p = 0.056).

Conclusion

Occult humeral surgical neck fractures occurred in 7.4% of isolated greater tuberosity fractures after re-evaluation, while missed humeral surgical neck fractures occurred in 4.4%.

Corrective Osteosynthesis in Failed Proximal Humeral Fractures

Despite implant improvement and increasing standardisation of operation techniques, the rate of therapy failure of proximal humeral fracture care with primary osteosyntheses is estimated to be 10 to 20%. Most commonly failure is precipitated by: material failure, technical error, non-anatomical repositioning, avascular necrosis, lacking medial support. An additive medial stabilisation of the so-called "calcar region" can decrease failure rates significantly. An early correction osteosynthesis with the purpose of restoring the anatomy is indicated in bony, non-consolidated "fresh" fractures. Bony consolidated fractures should be classified according to Boileau and Walch. The authors of this article advice a structured and classification-adapted approach to treatment with a correction osteosynthesis. Post-traumatic deficits can be augmented utilising the following methods: correction osteosynthesis with allogeneic/autologous bone grafts, correction osteosynthesis with hydroxyapatite grafts. For the additive stabilisation of repositioned and fixated fractures, the following are described: correction osteosynthesis with an additive ventral one-third tubular plate, correction osteosynthesis with cement-augmented screws. Based on results of endoprosthetics following fractures of the proximal humerus, the correction osteosynthesis indeed represents a real therapeutic alternative in patients that are below the age of 60, a good bone mass and with relative functional requirements.

Complications after surgical treatment of proximal humerus fractures in the elderly-an analysis of complication patterns and risk factors for reverse shoulder arthroplasty and angular-stable plating

BACKGROUND

To date, there is a lack of consensus regarding surgical treatment recommendations for complex proximal humerus fracture (PHF) patterns, especially between joint preservation and joint replacement techniques.

METHODS

Between 2012 and 2017, 146 patients (aged 74.1 ± 8.0 years) with complex PHF were treated with locking plates (open reduction-internal fixation [ORIF]) or reverse total shoulder arthroplasty (RTSA). Complications and unplanned revision surgery were recorded in a mid-term follow-up. Potential patient and surgical risk factors for complications were extracted. Univariate and multivariate analyses were conducted.

RESULTS

Follow-up data were available for 125 patients, 66 (52.8%) of whom were treated with locking plates, and 59 (41.2%) with RTSA. Both groups had comparable Charlson indices. The overall complication rate was 37.8% for ORIF and 22.0% for RTSA, with a revision rate of 12.1% and 5.1%, respectively, as driven primarily by persistent motion deficits. Multivariate analyses demonstrated no significant differences between the 2 procedures (P = .500). However, age was an independent protective factor against overall complications (P = .018). Risk factors for major complications in ORIF included osteoporosis, varus impaction fractures, posteromedial metaphyseal extensions <8 mm, head-shaft displacements >4 mm, and multifragmentary greater tuberosities. For RTSA, higher complication rates were seen in patients with higher Charlson indices, diabetes, or altered (greater) tuberosities. In contrast, Neer's classification system was not predictive in either group.

CONCLUSIONS

RTSA led to fewer complications than ORIF and thus can be considered a valuable option in complex PHF of the elderly. Paying attention to specific prognostic factors may help to reduce the complication rate.

Biomechanical evaluation of hybrid double plate osteosynthesis using a locking plate and an inverted third tubular plate for the treatment of proximal humeral fractures

Background

Treating proximal humerus fractures can be challenging because of large metaphyseal defects that conceal anatomical landmarks. In such cases, medial cortical support with, for example, calcar screws, is mandatory. Nevertheless, varus dislocations and implant failures in patients with impaired bone quality persist. Thus, the need for effective treatment of these patients exists. Hybrid double plate osteosynthesis was introduced as an alternative, yielding similar results as calcar screws. However, a biomechanical comparison of the stability of these two techniques is pending.

Methods

Cadaveric humeral specimens were treated with plate osteosynthesis and calcar screws (group 1, n = 9) or hybrid double plate osteosynthesis (group 2, n = 9) using a proximal humerus fracture model with a two-part fracture. Displacement, stiffness, failure mode, and ultimate load were examined biomechanically in a cyclic compressive-loading scenario.

Results

Although the hybrid double plate osteosynthesis (group 2) tended to confer higher stiffnesses than the medial support screws at higher cycles (group 1), this trend was below the level of significance. The displacement revealed non-significantly lower values for group 1 as compared with group 2 for cycles 50 and 2000, but at 5000 cycles, group 2 offered non-significantly lower displacement values than group 1. The ultimate load tended to be non-significantly higher in the hybrid double plate osteosynthesis group (group 2: 1342±369 N, group 1: 855±408 N). Both groups yielded similar failure rates, with the majority of failures in group 2 being gap closures (n = 8), whereas those in group 1 being plate dislocations (n = 4).

Conclusions

The use of an additive plate osteosynthesis in the region of the bicipital groove may be a potential alternative to the previously-established method of using calcar screws. The biomechanical data obtained in this study suggests that hybrid double plate osteosynthesis is as rigid and robust as calcar screws.

Biomechanical analysis of plate systems for proximal humerus fractures: a systematic literature review

BACKGROUND

Proximal humerus fractures are the third most common in the human body but their management remains controversial. Open reduction and internal fixation with plates is one of the leading modes of operative treatment for these fractures. The development of technologies and techniques for these plates, during the recent decades, promise a bright future for their clinical use. A comprehensive review of in vitro biomechanical studies is needed for the comparison of plates' mechanical performance and the testing methodologies. This will not only guide clinicians with plate selection but also with the design of future in vitro biomechanical studies. This review was aimed to systematically categorise and review the in vitro biomechanical studies of these plates based on their protocols and discuss their results. The technologies and techniques investigated in these studies were categorised and compared to reach a census where possible.

METHODS AND RESULTS

Web of Science and Scopus database search yielded 62 studies. Out of these, 51 performed axial loading, torsion, bending and/or combined bending and axial loading while 11 simulated complex glenohumeral movements by using tendons. Loading conditions and set-up, failure criteria and performance parameters, as well as results for each study, were reviewed. Only two studies tested four-part fracture model while the rest investigated two- and three-part fractures. In ten studies, synthetic humeri were tested instead of cadaveric ones. In addition to load-displacement data, three-dimensional motion analysis systems, digital image correlation and acoustic emission testing have been used for measurement.

CONCLUSIONS

Overall, PHILOS was the most tested plate and locking plates demonstrated better mechanical performance than non-locking ones. Conflicting results have been published for their comparison with non-locking blade plates and polyaxial locking screws. Augmentation with cement [calcium phosphate or poly(methyl methacrylate)] or allografts (fibular and femoral head) was found to improve bone-plate constructs' mechanical performance. Controversy still lies over the use of rigid and semi-rigid implants and the insertion of inferomedial screws for calcar region support. This review will guide the design of in vitro and in silico biomechanical tests and also supplement the study of clinical literature.

Hybrid blade and locking plate fixation for proximal humerus fractures: a comparative biomechanical analysis

BACKGROUND

Open reduction and internal fixation of proximal humerus fractures can be difficult to achieve adequate, complication free results due to osteopenia of the proximal humerus and unstable fracture patterns. This study aimed to compare the biomechanical properties of a novel hybrid fixed angle blade plate (Fx plate) with an established fixed angle locking plate (PHILOS plate).

METHODS

A two-part fracture was simulated in synthetic composite humeri by creating a transverse osteotomy and 10 mm fracture gap at the surgical neck. After treating the fractures with either an Fx plate or a PHILOS plate, humeral head was fixed and the shaft was displaced in a cantilever fashion. For elastic tests, loading was along the frontal and sagittal plane to achieve varus/valgus and extension/flexion, respectively. In plastic tests, loading was in a varus direction to determine the constructs' resistance to varus collapse.

RESULTS

In elastic tests, both construct types had higher peak load and stiffness in extension/flexion than varus/valgus. Fx plate constructs were significantly stiffer than PHILOS constructs in varus/valgus (mean: 7.590/6.900 vs. 6.609/6.091 N/mm; p < 0.001 for both) but significantly less stiff in extension/flexion (8.770/9.541 vs. 9.533/9.997 N/mm; p < 0.001 for extension, p < 0.05 for flexion). In varus plastic tests, significantly higher peak loads were reported for Fx plate than PHILOS (134.391 vs. 115.531 N; p < 0.001).

CONCLUSIONS

In this fracture gap model, humeri implanted with a novel Fx plate provided higher varus/valgus stiffness but lower extension/flexion stiffness than a more traditional proximal humeral locking plate design (PHILOS).

Shoulder muscle atrophy and its relation to strength loss in obstetrical brachial plexus palsy

BACKGROUND

Treatment/prevention of shoulder muscle strength imbalances are major therapeutic goals for children with obstetrical brachial plexus palsy. The study aims were to characterize muscle atrophy in children/adolescents with unilateral obstetrical brachial plexus palsy, to quantify the agonist-antagonist muscle volume balance and the association between muscle volume and strength.

METHODS

Eight boys and four girls (age=12.1, standard deviation=3.3) participated in this case-control study. Three-dimensional magnetic resonance images of both shoulders were acquired. The unimpaired shoulder served as a reference. Volumes of deltoid, pectoralis major, supraspinatus, infraspinatus, teres major, subscapularis were calculated based on 3D models, derived through image segmentation. Maximal isometric torques were collected in six directions.

FINDINGS

All the major muscles studied were significantly atrophied. The teres major demonstrated the biggest difference in atrophy between groups (51 percentage points), the pectoralis major was the least atrophied (23 percentage points). The muscle volume distribution was significantly different between shoulders. Muscle volume could predict maximal voluntary isometric torques, but the regression coefficients were weaker on the impaired side (72% to 91% of the strength could be predicted in the uninvolved side and 24% to 90% in the involved side and external rotation strength could not be predicted).

INTERPRETATION

This study demonstrates muscle atrophy varied across all the main shoulder muscles of the glenohumeral joint, leading to significant muscle volume imbalances. The weaker coefficients of determination on the impaired side suggest that other variables may contribute to the loss of strength in addition to atrophy.

Current concepts in locking plate fixation of proximal humerus fractures

Despite numerous available treatment strategies, the management of complex proximal humeral fractures remains demanding. Impaired bone quality and considerable comorbidities pose special challenges in the growing aging population. Complications after operative treatment are frequent, in particular loss of reduction with varus malalignment and subsequent screw cutout. Locking plate fixation has become a standard in stabilizing these fractures, but surgical revision rates of up to 25% stagnate at high levels. Therefore, it seems of utmost importance to select the right treatment for the right patient. This article provides an overview of available classification systems, indications for operative treatment, important pathoanatomic principles, and latest surgical strategies in locking plate fixation. The importance of correct reduction of the medial cortices, the use of calcar screws, augmentation with bone cement, double-plate fixation, and auxiliary intramedullary bone graft stabilization are discussed in detail.

Head-shaft angle changes during internal and external shoulder rotations: 2-D angulation in 3-D space

INTRODUCTION

Restoration of native head-shaft angle (HSA) is critical for treatment of proximal humerus fracture. However, HSA has not been properly investigated according to the humeral rotation. This study was designed to analyze the relationship between the humeral rotation and the HSA at 1° increments, and clarify its serial changing pattern according to the humeral rotation.

HYPOTHESIS

The angulation of HSA would be undervalued when the humerus is being rotated externally and it would be overvalued when it is being rotated internally.

MATERIALS AND METHODS

Eight dried cadaveric normal humeri were CT scanned. They were analyzed using computer-aided design with a standardized neutral position. HSA was the angle between the humeral shaft axis (SA) and the humeral head axis (HA). SA and HA were the best-fit lines through center of all the best-fitting circles in every cross section along the humeral shaft and within the humeral head, respectively. Each 3D model was rotated 30° internally and 45° externally relatives to the SA at 1° increments with the camera was fixed at antero-posterior view of neutral position. Angulation of HSA in every rotational degree was documented as ratio relatives to the angulation of HSA in neutral position.

RESULTS

The average HSA at neutral position was 133±1.93°. HSA was underestimated by 8±1.9% and it was overestimated by 20±5.1% at the maximum external rotation (ER) and internal rotation (IR), respectively. HSA was underestimated by 1% in every 5.8° of ER and overestimated by 1% in every 1.5° of IR. Rotational misalignments within 10° of IR and 18° of ER could be tolerated (P>.05).

CONCLUSIONS

HSA was underestimated at ER and was overestimated at IR. This information could be useful for surgeons in restoring the native HSA for treatment of proximal humerus fracture.

TYPE OF STUDY

Basic research study.

A new nail with a locking blade for complex proximal humeral fractures

INTRODUCTION

The objective of this study was to assess the clinical outcome of displaced proximal humerus fracture treated with a new locking blade nail.

MATERIALS AND METHODS

This prospective study included a series of 92 patients with acute fracture of the proximal humerus treated in one hospital level I trauma centre with locking blade nail between December 2010 and December 2013. According to the Neer classification, all fractures were two- to four-part fractures. Age adopted Constant score, DASH and visual analogue scores were used as outcome measures.

RESULTS

A total of 92 patients were enrolled in the study. However, 29 patients were excluded due to loss to follow-up and death. Ultimately, 63 patients were available for final follow-up and data analysis. The mean duration of follow-up was 22 months (range 16-48 months). On average at 1 year, all fractures had united. The mean weighted Constant score was 84.2 % and the median disabilities of the arm, shoulder and hand (DASH) score was 26, the range of elevation was 115 and range of abduction was 97. The head shaft angle was 130, and pain visual analogue was 1.6. We found that 5 of the 63 patients (8 %) demonstrated complications. Two patients (3 %) displayed secondary displacement and require device removal. Two patients (3 %) had impingement due to prominent metal work, and one patient had a superficial wound infection which was treated with a course of antibiotics.

CONCLUSION

Our study shows excellent results with new locking blade nail for displaced proximal humerus fractures. We think the locking blade nail offers stiff triangular fixation of the head fragment and support of the medial calcar region to prevent secondary varus collapse.

LEVEL OF EVIDENCE

III.

The bicipital groove as a landmark for reconstruction of complex proximal humeral fractures with hybrid double plate osteosynthesis

Background

Complex proximal humerus fractures with metaphyseal comminution remain challenging regarding reduction and stability. In most fracture patterns the hard bone of the bicipital groove remains intact. In this case series, we describe a novel technique of hybrid double plate osteosynthesis of complex proximal humerus fractures with metaphyseal comminution.

Methods

In randomly chosen shoulder specimens and synthetic bones, pilot studies for evaluation of the feasibility of the technique were performed. Between 4/2010 and 1/2012 10 patients underwent hybrid double plate osteosynthesis. Seven patients (4 male, 3 female, mean age was 50 years (range 27–73)) were available for retrospective analysis. Based on plain radiographs (anterior-posterior and axial view), the fractures were classified according to the Orthopaedic Trauma Association classification (OTA) and by descriptive means (head-split variant (HS), diaphyseal extension or comminution (DE)).

Results

Follow-up radiographs demonstrated complete fracture healing in six patients and one incomplete avascular necrosis. None of the patients sustained loss of reduction. Three patients where reoperated. The medium, not adapted, Constant score was 80 Points (58–94). Patients subjective satisfaction was graded mean 3 (range: 0–6) in the visual analog scoring system (VAS).

Conclusion

The technique of hybrid double plate osteosynthesis using the bicipital groove as anatomic landmark may re-establish shoulder function after complex proximal humerus fractures in two dimensions. Firstly the anatomy is restored due to a proper reduction based on intraoperative landmarks. Secondly additional support by the second plate may provide a higher stability in complex fractures with metaphyseal comminution.

The relevance of neutral arm positioning for true ap-view X-ray to provide true projection of the humeral head shaft angle

INTRODUCTION

Textbooks commonly recommend using the true anterior-posterior (ap)-view with the patient's arm in a sling and therefore in internal rotation (IR) for radiologic diagnostic assessment of the proximal humerus after trauma. However, IR or external rotation (ER) may affect the projection of the head shaft angle (HSA) and therefore bias the diagnostic conclusion significantly. We hypothesized that neutral rotation (NR) of the arm is mandatory for true ap-view to provide true projection of the HSA.

MATERIALS AND METHODS

A simplified geometrical model of the proximal humerus was used to examine the influence of different arm positions and angulations of the central ray in relation to the projection of the HSA.

RESULTS

Both ER and IR misleadingly suggested an increased valgus angle. Simulating the true ap-view with the central ray in cranio-caudal direction, IR changed the projection of the HSA substantially.

CONCLUSION

In conclusion, standard fixation of the patient's arm in a shoulder sling in IR for true ap-view may result in an oblique projection, potentially leading to incorrect surgical implications. To prevent misdiagnosed valgus or varus angulation, NR of the arm should be obeyed when performing true ap-view X-ray. We, therefore, highly recommend to overcome the traditionally arm position, ensuring the true amount of dislocation to assure correct surgical implications and comparable follow-up examinations.

Is there any advantage in placing an additional calcar screw in locked nailing of proximal humeral fractures?

BACKGROUND

The objective of this study was to evaluate the biomechanical effect of an additional unlocked calcar screw compared to a standard setting with three proximal humeral head screws alone for fixation of an unstable 2-part fracture of the surgical neck.

HYPOTHESIS

The additional calcar screw improves stiffness and failure load.

METHODS

Fourteen fresh frozen humeri were randomized into two equal sized groups. An unstable 2-part fracture of the surgical neck was simulated and all specimens were fixed with the MultiLoc(®)-nail. Group I represented a basic screw setup, with three locked head screws and two unlocked shaft screws. Group II was identical with a supplemental unlocked calcar screw (CS). Stiffness tests were performed in torsional loading, as well as in axial and in 20° abduction/20° adduction modes. Subsequently cyclic loading and load-to-failure tests were performed. Resulting stiffness, displacement under cyclic load and ultimate load were compared between groups using the t-test for independent variables (α=0.05).

RESULTS

No significant differences were observed between the groups in any of the biomechanical parameters. Backing out of the CS was observed in three cases.

DISCUSSION

The use of an additional unlocked calcar screw does not provide mechanical benefit in locked nailing of an unstable 2-part fracture of the surgical neck.

Allogenic bone grafting for augmentation in two-part proximal humeral fracture fixation in a high-risk patient population

INTRODUCTION

The surgical fixation of unstable, varus displaced two-part fractures of the proximal humerus remains challenging.

MATERIALS AND METHODS

In a case series of 10 non-compliant, high-risk patients (median age 63 years; range 52-78), a cancellous allograft was used to augment plate fixation of the fractures.

RESULTS

After a median follow-up of 28.5 months, all but one fracture were healed, with the bony allografts incorporated without any systemic or local complications. No significant loss of reduction or evidence of avascular necrosis of the humeral head was seen. The median Constant-Murley Score was 72.0 (range 45-86). Median pain on a visual analog scale was 1 (range 0-7). Median values for the range of motion were flexion: 155° (range 90-170), abduction: 168° (range 95-180) and external rotation: 43° (range: 30-50). Compared to the uninjured contralateral side, flexion was impaired by 13 %, abduction by 14 %, and external rotation by 15 %. Median abduction power was 64 % of the uninjured side. The median varus displacement was 51° (range 45-59) preoperatively, 4° (range -5 to 19) intraoperatively, and 13° (range 1-18) at the time of the final follow-up, relating to an improvement of 38° compared to the preoperative status.

CONCLUSIONS

The augmentation of proximal humeral fracture fixation using a cancellous allograft might be a viable and reliable alternative to prevent early varus failure and to, moreover, lead to bony union in a non-compliant or high-risk patient population.

Effect of Calcar Screw Use in Surgical Neck Fractures of the Proximal Humerus With Unstable Medial Support: A Biomechanical Study

OBJECTIVES

To evaluate the effect of calcar screw use in proximal humeral fractures with unstable medial support treated with locked plates.

METHODS

Standard osteotomies were performed in 36 cadaveric humeri to create a surgical neck fracture proximal humeral model. For static testing, 12 pairs of humeri were divided into 4 groups: normal alignment and varus deformity groups with and without 5-mm medial deficiencies. Calcar screw function was measured in each group by axial, shear, and torsion stiffness tests. Another 6 pairs of humeri with 5-mm medial deficiencies were subjected to cyclic loading tests in the normal alignment model with and without calcar screw application.

RESULTS

Calcar screws improved rotational stability in the normal alignment (P = 0.007) and varus (P = 0.002) groups. Calcar screws improved static and cyclic axial (P = 0.004) and shear (P = 0.017) stability in the normal alignment group with medial deficiency. In specimens with normal alignment and intact medial cortex, calcar screws provided no advantage in axial (P = 0.535) or shear (P = 0.537) stiffness. Calcar screws did not provide sufficient axial (P = 0.782) or shear (P = 0.772) stability to avoid reduction loss in humeri with varus malreduction.

CONCLUSIONS

In humeri with normal alignment, calcar screws can provide additional stability even when a medial deficiency exists. The use of calcar screws in humeri with varus deformity showed no biomechanical superiority.

Biomechanical effects of calcar screws and bone block augmentation on medial support in locked plating of proximal humeral fractures

BACKGROUND

The objective of this study was to investigate the biomechanical effects of medial fracture gap augmentation in locked plating of an unstable 2-part proximal humeral fracture with calcar screws and insertion of a corticocancellous bone block. Furthermore the mechanical behavior of dynamic locking screws in the non-parallel arrangement of a proximal humeral plate was of interest.

METHODS

Thirty-two fresh frozen humeri were randomized in four equal groups. An unstable 2-part fracture was fixed by locked plating in all specimens. The basic screw setup was supplemented by additional calcar screws in one group. Humeral head screws were replaced by dynamic locking screws in a second group. The third group featured an additional corticocancellous femoral head allograft. Assessment of stiffness was followed by cyclic loading and load to failure tests. Resulting stiffness, fracture gap deflection and ultimate load were compared utilizing Bonferroni corrected t-test for independent samples.

FINDINGS

The mechanical effect of additional calcar screws was non-significant as compared to the basic screw configuration whereas bone block insertion significantly increased construct stiffness and failure load. The use of dynamic locking screws did not significantly reduce construct stiffness when compared to conventional locking screws.

INTERPRETATION

Additional calcar screws alone did not improve the initial biomechanical properties of an unstable 2-part proximal humeral fracture model. However bone block augmentation appeared to be a reliable alternative of additional bony support by raising stiffness and failure load. Dynamic locking screws did not show their expected dynamic component when used in a non-parallel arrangement.

Radiological evaluation of reduction loss in unstable proximal humeral fractures treated with locking plates

PURPOSE

The aim of this study was to radiologically evaluate the risk of reduction loss after locking plate fixation of proximal humerus fractures.

METHODS

From September 2007 to April 2009, 71 patients (28 males, 43 females) with unstable proximal humeral fracture were treated with open reduction and internal fixation by locking plate. The mean follow-up time was 31.2 months (range: 26-47). The head-shaft angulation (HSA) and the humeral head height (HHH) in true anteroposterior (AP) were recorded and compared over time. All complications were noted. Shoulder function was measured by the Constant score.

RESULTS

Patients with ΔHSA >10° (t=2.740, P=0.008) and ΔHHH >5mm (t=2.55, P=0.019) were more likely to have impaired shoulder function. Varus collapse occurred most frequently in patients with initial reduction of HSA <125° (χ(2)=19.17, P<0.001, Fisher's exact test F<0.001). Patients with >5mm HHH decrease were strongly associated with loss of reduction (χ(2)=24.23, P<0.001, F<0.001).

CONCLUSIONS

Dynamic change of HSA >10° and HHH >5mm were radiological factors that indicated poor shoulder function. Intra-operative HSA >125° should be achieved to avoid reduction loss following locking plate fixation of proximal humerus fracture.

LEVEL OF EVIDENCE

level IV.

Three-dimensional humeral morphologic alterations and atrophy associated with obstetrical brachial plexus palsy

BACKGROUND

Obstetrical brachial plexus palsy (OBPP) is a common birth injury, resulting in severe functional losses. Yet, little is known about how OBPP affects the 3-dimensional (3D) humeral morphology. Thus, the purpose of this study was to measure the 3D humeral architecture in children with unilateral OBPP.

METHODS

Thirteen individuals (4 female and 9 male patients; mean age, 11.8 ± 3.3 years; mean Mallet score, 15.1 ± 3.0) participated in this institutional review board approved study. A 3D T1-weighted gradient-recalled echo magnetic resonance image set was acquired for both upper limbs (involved and noninvolved). Humeral size, version, and inclination were quantified from 3D humeral models derived from these images.

RESULTS

The involved humeral head was significantly less retroverted and in declination (medial humeral head pointed anteriorly and inferiorly) relative to the noninvolved side. Osseous atrophy was present in all 3 dimensions and affected the entire humerus. The inter-rater reliability was excellent (intraclass correlation coefficient, 0.96-1.00).

DISCUSSION

This study showed that both humeral atrophy and bone shape deformities associated with OBPP are not limited to the axial plane but are 3D phenomena. Incorporating information related to these multi-planar, 3D humeral deformities into surgical planning could potentially improve functional outcomes after surgery. The documented reduction in retroversion is an osseous adaptation, which may help maintain glenohumeral congruency by partially compensating for the internal rotation of the arm. The humeral head declination is a novel finding and may be an important factor to consider when one is developing OBPP management strategies because it has been shown to lead to significant supraspinatus inefficiencies and increased required elevation forces.

Proximal humeral fracture treatment in adults

Most proximal humeral fractures affect elderly patients and can be treated nonoperatively with good functional outcomes.The treatment of displaced three and four-part fractures remains controversial and depends on a variety of underlying factors related to the patient (e.g., comorbidity, functional demand), the fracture (e.g., osteoporosis), and the surgeon (e.g., experience).Throughout the literature, open reduction and locking plate osteosynthesis is associated with considerable complication rates, particularly in the presence of osteoporosis.Low local bone mineral density, humeral head ischemia, residual varus displacement, insufficient restoration of the medial column, and nonanatomic reduction promote failure of fixation and impair functional outcome.The outcome of hemiarthroplasty is closely related to tuberosity healing in an anatomic position to enable the restoration of rotator cuff function. Reverse shoulder arthroplasty may provide satisfactory shoulder function in geriatric patients with preexisting rotator cuff dysfunction or after the failure of first-line treatment.

Calcar comminution as prognostic factor of clinical outcome after locking plate fixation of proximal humeral fractures

OBJECTIVE

In the treatment of proximal humeral fractures, the decision between open fixation and arthroplasty is often difficult. Applicable radiographic prognostic factors would be useful. The purpose of the present study was to investigate the influence of calcar comminution on the clinical and radiologic outcome after locking plate fixation of these fractures.

METHODS

In patients with proximal humeral fractures that were treated by locking plate fixation, fracture morphology and the presence of comminution of the calcar were documented on preoperative radiographs. Follow-up for at least 2 years with radiologic assessment and functional outcome measurements including Constant score, subjective shoulder value (SSV), disabilities of the arm, shoulder and hand score (DASH), visual analogue scale (VAS) and short form (SF)-36 was performed.

RESULTS

Follow-up examination (50.8±20.6 months) was possible in 74 patients (46 female, 28 male, age 63.0±15.9 years). Mean absolute Constant score (CS abs), CS adapted to age and gender (CS adap), DASH, SSV and VAS were 72.4±14.5, 85.2±17.3%, 15.7±17.3, 80.3±19.6% and 2.1±2.2. Nonunion was present in 1.3%, cut-out in 5.4% and implant failure in 1.3%. Avascular necrosis (AVN) was seen in 12.2%, in three cases >24 months after the initial trauma. In the presence of calcar comminution, the clinical outcome (CS abs, CS adap, SSV and several parameters of SF-36) was significantly impaired, the odds ratio for these patients to have an absolute CS<65 was 4.4 (95% confidence interval (CI): 1.4-13.7).

CONCLUSIONS

The treatment of proximal humeral fractures with locking plate fixation achieves good clinical mid-term results. Calcar comminution is a relevant and easy-to-detect prognostic factor for the functional and subjective outcome in these fractures.