Open Reduction and Long Locking Plate Fixation of Complex Proximal Humeral Metadiaphyseal Fractures.

BACKGROUND: A minority of proximal humeral fractures extend into the diaphysis and their optimal treatment remains controversial. We evaluated the outcomes and risk of complications in patients with these injuries, treated by a protocol of open reduction and long locking plate fixation (LPF). METHODS: Between 2007 and 2014, all locally resident patients with a proximal humeral fracture extending into the diaphysis were referred to a specialist shoulder clinic. Operative treatment using a protocol of open reduction and LPF was offered to medically fit patients. Those with 2-year radiographic follow-up were included in the study, and standardized assessments of clinical and radiographic outcomes were performed during the first 2 years postoperatively. At a mean of 8.8 years (range, 5 to 12 years) after LPF, the functional outcomes and satisfaction of surviving, cognitively intact patients were assessed with a questionnaire study. RESULTS: One hundred and two patients met the inclusion criteria; the majority were older women who had incurred the injury during a simple fall. Fractures were divided into 2 types depending on the pattern of diaphyseal extension. The pain levels, functional scores, and satisfaction with treatment were satisfactory both at the 2-year follow-up and at the longer-term follow-up at a mean of 8.8 years postsurgery. Complications were predominantly due to postsurgical stiffness (in 7 patients, with 3 undergoing additional surgery) and nonunion or fixation failure (in 7 patients, with 6 undergoing additional surgery). CONCLUSIONS: Proximal humeral fractures with diaphyseal extension are rare. The results of our study support the use of LPF in medically stable patients in centers with the expertise to perform these procedures. LEVEL OF EVIDENCE: Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Bilateral posterior fracture-dislocation of the shoulders: Two rare case reports and literature review.

RATIONALE: Bilateral posterior fracture-dislocation of the shoulders occurs rarely and the diagnosis is often challenging. This injury is often missed or delayed on initial presentation, leading to continuous pain, disability, and rising medical costs. Timely diagnosis and proper treatment are very important to restore shoulder function. PATIENT CONCERNS: Here we report 2 rare cases. Case 1 was a 53-year-old physical worker with severe pain and limited shoulder movement after an unexpected fall. Case 2 was a 55-year-old man with pain in upper limbs and shoulders after an electric shock. DIAGNOSIS: Both of them were diagnosed as bilateral posterior fracture-dislocation of the shoulders by computed tomography (CT) scan. INTERVENTION: After systematic preoperative evaluation, both of them were treated with open reduction and internal fixation. OUTCOMES: After 16 months follow-up, case 1 was pain-free in both shoulders. He had returned to full activity and was satisfied with his level of function. At 24 months follow-up, both shoulders of case 2 were painless and stable with acceptable range of motion and he was able to carry out daily activities. LESSONS: Our case reports highlight that bilateral posterior fracture-dislocation of the shoulders is easy to be missed; one way to prevent missing diagnosis is to suspect cases with pain and limited external rotation, especially those with a history of seizures, electric shock, or severe trauma; appropriate history inquiry, physical examination, proper shoulder images are the key to correct diagnosis.

Reproducibility of the modified Neer classification defining displacement with respect to the humeral head fragment for proximal humeral fractures.

BACKGROUND: Although the Neer classification is widely used for the assessment of proximal humeral fractures, its reproducibility has been challenged. The purpose of this study was to evaluate the reproducibility of the conventional Neer classification and a modified classification that defined fracture displacement with respect to the humeral head fragment. METHODS: The fracture patterns in 80 cases of proximal humeral fractures were independently assessed by 6 observers. The cases were grouped according to the conventional Neer classification using radiographs followed by computed tomography (CT) scans by each examiner twice with a 1-month interval. The fractures were then classified with the modified Neer classification, which defined displacement of the fragment as separation of more than 1 cm or angulation of more than 45° from the humeral head fragment, twice with a 1-month interval. Kappa coefficients of the conventional and modified Neer classifications were compared. RESULTS: The modified classification showed significantly higher intra-observer agreement than the conventional classification, both for radiographs (P = .028) and for CT scans (P = .043). Intra-observer agreement was also significantly higher for the modified classification than for the conventional classification, both for radiographs (P = .001) and for CT scans (P < .001). CONCLUSIONS: The present study showed that agreement for the Neer classification could be improved when fracture displacement was defined as separation or angulation from the humeral head. Considering vascularity to the humeral head, furthermore, the modified method might be more helpful for predicting patients' prognosis than the conventional Neer classification.

Continuous Paravertebral Nerve Block for Scapula Fracture Analgesia: A Case Report.

A 46-year-old man presented with severe refractory posterior shoulder pain due to a left scapular fracture sustained during a motor vehicle collision. Despite multimodal oral and intravenous analgesics, the patient's pain remained difficult to control. A continuous paravertebral nerve block was performed between the second and third thoracic vertebrae resulting in excellent analgesia of the scapular pain. This case suggests that a continuous thoracic paravertebral block placed between the second and third vertebrae may be considered as part of multimodal analgesia in patients with scapular fractures.

Predictive value of valgus head-shaft angle in identifying Neer 4-part proximal humerus fractures. A radiographic and CT-scan analysis of 120 cases.

BACKGROUND AND AIM OF THE WORK: Understanding the fracture morphology and its relation to the expected outcome and risk of complications is fundamental for proximal humerus fractures (PHFs) management. Most Neer 3- and 4-part fractures may deserve surgical treatment. Unfortunately, plain x-rays may not be able to differentiate between a 3- or 4-part fractures unless an axillary or analogue projection is carried out. Aim of the present study is to evaluate whether a high valgus head-shaft angle degree is predictive of a Neer 4-part rather than a 3-part fracture. METHODS: The study included 120 3-(75 cases) and 4-(45 cases) part PHFs (valgus displaced in 98 cases), M:F ratio = 1:2.6, mean age 65.7 years, classified on CT scan images. The humeral head shaft angle was calculated on AP x-rays and statistically correlated with 3 and 4-part fractures to identify values predictive of 4-part fracture. RESULTS: Valgus head/shaft angle was significantly higher in 4-part fractures, especially in the valgus displaced group (p < 0.001). A cutoff value of 168.5° was identified as predictive of a 4-part fracture with a sensibility of 74% and specificity of 78%. Increasing by 1 degree the humeral head-shaft angle, the chance to have a 4-part fracture increases of 3% in the whole population and of 11% in the valgus sub-group. CONCLUSION: The severity of PHF can be predicted analysing valgus head shaft angle on AP x-rays with a sensibility of 74% and specificity of 78% in identifying a 4-part fracture with a cutoff value of 168.5°.

Primary reverse shoulder arthroplasty for acute proximal humerus fractures: A 5-year long term retrospective study of elderly patients.

BACKGROUND: Reverse shoulder arthroplasty (RSA) in complex shoulder fractures is ever more frequently. This study compares clinical and radiologic results of patients with comminuted proximal humeral fractures (PHFs) treated with RSA, with and without tuberosities grafting. METHODS: Between January 2009 and June 2014, 55 patients aged ≥65 years with 3- and 4-part PHFs were treated surgically. Patients' files and the hospital's digital database were reviewed retrospectively with at least 5-year of follow up. We constituted three groups according to the tuberosity consolidation: patients in whom the tuberosities showed anatomic consolidation (Group I) and patients either with secondary displacement of the tuberosities (Group II) or without tuberosity repair (Group III). RESULTS: The 74% of the repaired tuberosities consolidated in anatomic position. Among range of motion (ROM), we reported that forward elevation, abduction and external rotation were significantly better in Group I than those in Group II-III. Furthermore, quick Dash score and Constant score showed more satisfied results in Group I. Regarding complications, not infection or instability were found in group I. On the other hand, in group II, we reported one patient with deep infection, leading to two steps surgery. In group III, we recorded two patients with instability required implant revision and one with deep infection treated by revision. CONCLUSION: RSA showed satisfied results even at 5 year follow up. Preservation of the tuberosities in anatomic position improves active forward elevation and external rotation as well as patient satisfaction with less complications.

Intramedullary nailing of displaced four-part fractures of the proximal humerus.

BACKGROUND: Intramedullary nailing is already established technique for the treatment of two and three-part fractures of proximal humerus. The aim of the study was to prospectively evaluate the efficacy and functional outcome after treatment of four-part fractures of proximal humerus with Multiloc proximal humeral nail. DESIGN: prospective monocentric cohort study. SETTING: single level 1 traumacenter. MATERIALS AND METHODS: From February 2011 to March 2016, 40 patients with displaced four-part proximal humeral fractures were treated with intramedullary nail inserted through anterolateral approach. Minimum one year follow up completed 35 patients and were involved into the study. RESULTS: After mean follow up period of 25.8 months 29 of 35 fractures healed. Average absolute Constant score in all 35 patients reached 57.7 points, relative side related Constants score 66.8% of contralateral extremity. Together there were 20 complications. in 6 cases (17%) developed complete avascular necrosis of the head. One deep infection was treated by implantation of antibiotic cement discs. Twelve secondary surgeries were performed, mostly for avascular necrosis development. Function and pain were significantly influenced by the quality of fracture reduction (p < 0.05) and development of complete AVN (p = 0.001). Group of 29 patients without AVN reached relative Constant score 73% of contralateral extremity. CONCLUSIONS: Intramedullary nailing can be used as possible fixation technique for the treatment of four-part fractures of proximal humerus. In experienced hands provides nailing osteosynthesis similar results as reconstruction with locking plates. Appropriate reduction of fracture fragments is the key for good functional result. LEVEL OF EVIDENCE: Level 2b - monocentric prospective cohort study.

Surgical and Non-Surgical Treatment for 3-Part and 4-Part Fractures of the Proximal Humerus: A Systematic Review of Overlapping Meta-Analyses.

This systematic review of overlapping meta-analyses was conducted to propose a principle to make decisions for comparing clinical safety and efficacy of surgical and non-surgical treatment for displaced 3-part and 4-part fractures of the proximal humerus. Three electronic databases (PubMed, EMBASE, and the Cochrane Library) were systematically searched to retrieve available published systematic reviews and meta-analyses comparing surgical versus non-surgical treatment for displaced 3-part and 4-part fractures of the proximal humerus. Ten meta-analyses were identified for this investigation. Based on the application of selection with the Jadad algorithm, a meta-analysis including 6 randomized clinical trials was selected for this systematic review, which demonstrated the best available evidence that no statistically significant differences were found in the Constant score, health-related quality of life, and mortality between surgical and non-surgical treatments for displaced 3-part and 4-part fractures of the proximal humerus; however, surgical treatment was associated with a significant increase in the incidence of reoperation. This systematic review of  overlapping meta-analyses reveals that although surgical treatment is more advantageous than and superior to non-surgical treatment for displaced 3-part and 4-part fractures of the proximal humerus, the former leads to a higher incidence of postoperative complications.

Humeral head histopathological changes in cuff tear arthropathy.

PURPOSE: The aim of this study was to investigate the histopathological changes in the humeral head in cuff tear arthropathy (CTA) compared with those in glenohumeral osteoarthritis (OA) and humeral neck fracture, which served as non-cuff tear controls. METHODS: Twenty-three humeral heads extracted at the time of shoulder prosthesis arthroplasty between June 2014 and July 2015 were evaluated in the present study. The diagnoses included four-part humeral neck fracture ( n = 4; average age, 85.0 years), glenohumeral OA ( n = 4; average age, 71.0 years), and CTA ( n = 15; average age, 73.0 years). The humeral heads were evaluated pathologically by hematoxylin and eosin and Safranin-O staining, and the thickness of the articular cartilage was measured. RESULTS: Fibrillation, thinning, and tearing of the cartilage were observed in the superior area of the humeral heads in CTA and glenohumeral OA. In CTA cases, clusters of chondrocytes in the cartilage were observed. Moreover, the thickness of the cartilage layer in the middle of the humeral head was 1.54 ± 0.07, 0.32 ± 0.46, and 2.19 ± 0.50 mm in humeral neck fracture, glenohumeral OA, and CTA, respectively. The cartilage layer in CTA was thicker than that in glenohumeral OA (CTA vs. OA: p < 0.05). CONCLUSION: OA changes in the superior area of the humeral heads and thickening of the cartilage layer from the middle to the inferior of the humeral heads were confirmed histopathologically, suggesting that simultaneous mechanical and nutritional factors might be contributing to CTA pathogenesis. The current study provided the better understanding of cartilage damage and thickening in CTA. This will help guide treatment options in the setting of CTA.

Inferomedial cortical bone contact and fixation with calcar screws on the dynamic and static mechanical stability of proximal humerus fractures.

BACKGROUND: This study aimed to explore the effect of retaining inferomedial cortical bone contact and fixation with calcar screws on the dynamic and static mechanical stability of proximal humerus fractures treated with a locking plate. METHODS: Twelve Synbone prosthetic humeri (SYNBONE-AG, Switzerland) were used for a wedge osteotomy model at the proximal humerus, in four groups. In the cortex contact + screw fixation group and cortex contact group, the inferomedial cortical bone contact was retained. In the screw fixation group and control group, the inferomedial cortical bone contact was not retained. Calcar screw fixation was implemented only in the screw fixation groups. The dynamic and static mechanical stability of the models were tested with dynamic fatigue mechanics testing, quasi-static axial compression, three-point bending, and torsion testing. RESULTS: The cortex contact + screw fixation group showed the longest fatigue life and the best stability. There was 35% difference in fatigue life between the cortex contact + screw fixation group and the cortex contact group, 43%between the cortex contact + screw fixation group and screw fixation group, and 63% between the cortex contact + screw fixation group and screw fixation group (P < 0.01). The cortex contact + screw fixation group showed the best axial compressive stiffness, bending stiffness, and torsion stiffness; these were successively decreased in the other three groups (P < 0.01). CONCLUSION: Retaining inferomedial cortical bone contact and fixation with two calcar screws maintained fracture stability with the highest strength and minimum deformation. Of the two methods, restoration of the inferomedial cortical bone support showed better dynamic and static biomechanical properties than placement of calcar screws alone.

Size of greater tuberosity fragment: a risk of iatrogenic injury during shoulder dislocation reduction.

PURPOSE: Shoulder dislocation with greater tuberosity fractures (GTF) is becoming increasingly common, as is the number of cases of iatrogenic humeral neck fractures (IHNF) during reduction. This study investigated the relationship between size of greater tuberosity fragment and occurrence of IHNF in patients with shoulder dislocation and GTF. METHODS: A retrospective study was made to identify all patients presenting with shoulder dislocation with GTF between September 2014 and July 2016. There were 74 patients with an average age of 52.4 years (range 18-84 years) representing 76 cases of shoulder dislocation associated with GTF. Patient age, injury mechanism and location, treatment waiting time, and reduction method were noted. Using conventional anterior-posterior view radiographs, three points were identified as A, B, and C. Distance ratios between AC and AB were calculated, then the resulting ratio was compared to a critical value of 0.4. RESULTS: More iatrogenic fractures occurred in cases where the AC/AB ratio exceeded 0.4. Most (13) occurred during emergency Hippocratic manual reduction. Only five of 18 iatrogenic fractures (27.78%) occurred during surgery while under traction. Women ran a higher risk of iatrogenic fracture than men (female/male ratio 8:1). On average, women were older than men at the time of fracture (59.75 years for women vs. 42 years for men). CONCLUSIONS: A statistically significant relationship exists between size of greater tuberosity fragment and occurrence of iatrogenic humeral neck fractures during the reduction of shoulder dislocation. The larger the greater tuberosity fragment, the higher the incidence of iatrogenic humeral neck fractures. For such fracture dislocations, we recommend open reduction with internal fixation directly and using a Kirschner wire in advance to reinforce the proximal humerus before reduction of the shoulder.

Computer-Assisted Virtual Surgical Technology Versus Three-Dimensional Printing Technology in Preoperative Planning for Displaced Three and Four-Part Fractures of the Proximal End of the Humerus.

BACKGROUND: This study aimed to determine the difference between computer-assisted virtual surgical technology and 3-dimensional (3D) printing technology in preoperative planning for proximal humeral fractures. METHODS: Between February 2009 and October 2015, 131 patients with 3 and 4-part proximal humeral fractures were divided into 3 groups on the basis of the preoperative planning method: conventional (n = 53), virtual surgical (n = 46), and 3D printing (n = 32). Fracture characteristics and intraoperative realization of preoperative planning (reduction shape and implant choices) were evaluated. Postoperative functional outcomes were assessed using the American Shoulder and Elbow Surgeons, Constant-Murley, and Short Form-36 (SF-36) scoring systems and shoulder range of motion; postoperative radiographic outcomes were assessed with respect to the loss of the neck-shaft angle (NSA) and loss of humeral head height (HHH). RESULTS: Excellent sensitivity, specificity, and accuracy for fracture characteristics were seen in all 3 groups. The correlations for NSA (p = 0.033) and HHH (p = 0.035) were higher in the virtual surgical group than in the 3D printing group. The lengths of the medial support screws in the actual choices were shorter than those in the preoperative plan for the 3D printing group, but a similar pattern was not seen in the virtual surgical group. Compared with the conventional method, the virtual surgical and 3D printing methods of preoperative planning resulted in shorter operative time, less blood loss, and fewer fluoroscopic images. The functional outcomes in both the 3D printing and virtual surgical groups were better than those in the conventional group. The virtual surgical method was faster than the 3D printing method, as suggested by a shorter time to surgery (2.5 compared with 4.6 days; p < 0.001), a shorter time for preoperative planning (30.4 compared with 262.4 minutes; p < 0.001), and a decreased duration of hospital stay (10.9 compared with 14.6 days; p < 0.001). CONCLUSIONS: The clinical outcomes in both the virtual surgical and 3D printing groups were better than those in the conventional group. However, computer-assisted virtual surgical technology is more convenient and efficient, considering the shorter time for preoperative planning. In addition, it has improved correlation with preoperative planning. LEVEL OF EVIDENCE: Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.

Biomechanical comparison of screw-based zoning of PHILOS and Fx proximal humerus plates.

BACKGROUND: Treatment of proximal humerus fractures with locking plates is associated with complications. We aimed to compare the biomechanical effects of removing screws and blade of a fixed angle locking plate and hybrid blade plate, on a two-part fracture model. METHODS: Forty-five synthetic humeri were divided into nine groups where four were implanted with a hybrid blade plate and the remaining with locking plate, to treat a two-part surgical neck fracture. Plates' head screws and blades were divided into zones based on their distance from fracture site. Two groups acted as a control for each plate and the remaining seven had either a vacant zone or blade swapped with screws. For elastic cantilever bending, humeral head was fixed and the shaft was displaced 5 mm in extension, flexion, valgus and varus direction. Specimens were further loaded in varus direction to investigate their plastic behaviour. RESULTS: In both plates, removal of inferomedial screws or blade led to a significantly larger drop in varus construct stiffness than other zones. In blade plate, insertion of screws in place of blade significantly increased the mean extension, flexion valgus and varus bending stiffness (24.458%/16.623%/19.493%/14.137%). In locking plate, removal of screw zones proximal to the inferomedial screws reduced extension and flexion bending stiffness by 26-33%. CONCLUSIONS: Although medial support improved varus stability, two inferomedial screws were more effective than blade. Proximal screws are important for extension and flexion. Mechanical consequences of screw removal should be considered when deciding the number and choice of screws and blade in clinic.

The influence of local bone quality on fracture pattern in proximal humerus fractures.

INTRODUCTION: Bone mineral density and fracture morphology are widely discussed and relevant factors when considering the different treatment options for proximal humerus fractures. It was the aim of this study to investigate the influence of local bone quality on fracture patterns of the Neer classification as well as on fracture impaction angle in these injuries. MATERIALS AND METHODS: All acute, isolated and non-pathological proximal humerus fractures admitted to our emergency department were included. The fractures were classified according to Neer and the humeral head impaction angle was measured. Local bone quality was assessed using the Deltoid Tuberosity Index (DTI). The distribution between DTI and fracture pattern was analysed. RESULTS: 191 proximal humerus fractures were included (61 men, mean age 59 years; 130 women, mean age 69.5). 77 fractures (40%) were classified as one-part, 72 (38%) were two-part, 24 (13%) were three- and four-part and 18 (9%) were fracture dislocations. 30 fractures (16%) were varus impacted, whereas 45 fractures (24%) were classified as valgus impacted. The mean DTI was 1.48. Valgus impaction significantly correlated with good bone quality (DTI ≥ 1.4; p = 0.047) whereas no such statistical significance was found for the Neer fracture types. DISCUSSION: We found that valgus impaction significantly depended on good bone quality. However, neither varus impaction nor any of the Neer fracture types correlated with bone quality. We conclude that the better bone quality of valgus impacted fractures may be a reason for their historically benign amenability to ORIF. On the other hand, good local bone quality does not prevent fracture comminution.

A scale-space curvature matching algorithm for the reconstruction of complex proximal humeral fractures.

The optimal surgical treatment of complex fractures of the proximal humerus is controversial. It is proven that best results are obtained if an anatomical reduction of the fragments is achieved and, therefore, computer-assisted methods have been proposed for the reconstruction of the fractures. However, complex fractures of the proximal humerus are commonly accompanied with a relevant displacement of the fragments and, therefore, algorithms relying on the initial position of the fragments might fail. The state-of-the-art algorithm for complex fractures of the proximal humerus requires the acquisition of a CT scan of the (healthy) contralateral anatomy as a reconstruction template to address the displacement of the fragments. Pose-invariant fracture line based reconstruction algorithms have been applied successful for reassembling broken vessels in archaeology. Nevertheless, the extraction of the fracture lines and the necessary computation of their curvature are susceptible to noise and make the application of previous approaches difficult or even impossible for bone fractures close to the joints, where the cortical layer is thin. We present a novel scale-space representation of the curvature, permitting to calculate the correct alignment between bone fragments solely based on corresponding regions of the fracture lines. The fractures of the proximal humerus are automatically reconstructed based on iterative pairwise reduction of the fragments. The validation of the presented method was performed on twelve clinical cases, surgically treated after complex proximal humeral fracture, and by cadaver experiments. The accuracy of our approach was compared to the state-of-the-art algorithm for complex fractures of the proximal humerus. All reconstructions of the clinical cases resulted in an accurate approximation of the pre-traumatic anatomy. The accuracy of the reconstructed cadaver cases outperformed the current state-of-the-art algorithm.

Effectiveness and Safety of Interventions for Treating Adults with Displaced Proximal Humeral Fracture: A Network Meta-Analysis and Systematic Review.

PURPOSE: Network meta-analysis (NMA) is a comparatively new evidence-based technique in medical disciplines which compares the relative benefits associated with multiple interventions and obtains hierarchies of these interventions for various treatment options. We evaluated the effectiveness and safety of open reduction and internal fixation (ORIF), hemiarthroplasty (HA), reverse shoulder arthroplasty (RSA), intramedullary nailing (IN) and non-operative treatment (NOT) of displaced proximal humeral fractures in adults using Bayesian NMA of data from clinical trials. METHOD: PUBMED, EMBASE and CENTRAL in July 2016 were searched and clinical trials that evaluated interventions for treating adults with displaced proximal humeral fractures were identified. Methodological qualities of studies were assessed by the Newcastle-Ottawa Scale and risk of bias using the Cochrane Collaboration tool. RESULT: Thirty-four trials involving 2165 participants were included in the study. RSA had significantly the highest Constant score and lower total incidence of complications than ORIF, HA and IN. Moreover, RSA resulted in a lower incidence of additional surgery than ORIF and IN. The rank of treatments in terms high Constant score was: RSA, ORIF, IN, NOT and HA. The rank for reduction in total incidence of complications was: RSA, NOT, HA, IN and ORIF. For lowering the risk of additional surgery, the rank was: RSA, NOT, HA, IN and ORIF. CONCLUSION: RSA had the highest probability for improving functional outcome and reduction in the total incidence of complications and requiring additional surgery among the five interventions for treating adults with displaced proximal humeral fracture.

Robotic Assessment of Upper Limb Function after Proximal Humeral Fracture: Personal Experience as A Patient and Occupational Therapist.

Robotics is an emerging field in rehabilitation medicine. Robots have the potential to complement traditional clinical assessments because they can measure functions more precisely and quantitatively than current clinical assessments. We present a patient with a proximal humeral fracture whose recovery process was evaluated with an exoskeleton robotic device. The patient, a 34-year-old woman, suffered a left proximal humeral fracture while snowboarding. She is an occupational therapist and is the first author of this study. With conservative therapy, fracture union was seen on X-ray at 6 weeks post-injury. At that time, the patient was permitted to move her left upper limb actively within the tolerance of pain. We assessed the function of the injured upper limb at 6, 7, and 12 weeks post-injury with the KINARM exoskeleton robotic device and with conventional clinical measures. The active range of motion and the muscle strength of the left shoulder improved over time. Using robotic assessment, the precise movement profiles, position sense, and functional ability of both arms were quantified and also showed progressive improvement over time. Assessment with a robotic device of the recovery process after proximal humeral fracture allowed quantification of functional impairments that could not be felt subjectively nor identified with conventional clinical assessments.

Biomechanical effect of the configuration of screw hole style on locking plate fixation in proximal humerus fracture with a simulated gap: A finite element analysis.

BACKGROUND: Locking plate fixation for proximal humeral fractures is a commonly used device. Recently, plate breakages were continuously reported that the implants all have a mixture of holes allowing placement of both locking and non-locking screws (so-called combi plates). In commercialized proximal humeral plates, there still are two screw hole styles included "locking and dynamic holes separated" and "locking hole only" configurations. It is important to understand the biomechanical effect of different screw hole style on the stress distribution in bone plate. METHODS: Finite element method was employed to conduct a computational investigation. Three proximal humeral plate models with different screw hole configurations were reconstructed depended upon an identical commercialized implant. A three-dimensional model of a humerus was created using process of thresholding based on the grayscale values of the CT scanning of an intact humerus. A "virtual" subcapital osteotomy was performed. Simulations were performed under an increasing axial load. The von Mises stresses around the screw holes of the plate shaft, the construct stiffness and the directional displacement within the fracture gap were calculated for comparison. RESULTS: The mean value of the peak von Mises stresses around the screw holes in the plate shaft was the highest for combi hole design while it was smallest for the locking and dynamic holes separated design. The stiffness of the plate-bone construct was 15% higher in the locking screw only design (132.6N/mm) compared with the combi design (115.0N/mm), and it was 4% higher than the combi design for the locking and dynamic holes separated design (119.5N/mm). The displacement within the fracture gap was greatest in the combi hole design, whereas it was smallest for the locking hole only design. CONCLUSIONS: The computed results provide a possible explanation for the breakages of combi plates revealed in clinical reports. The locking and dynamic holes separated design may be a better configuration to reduce the risk of plate fracture.