Biomechanical Study of the Fixation Strength of Anteromedial Plating for Humeral Shaft Fractures

The application of a dual-lead locking screw could enhance the reduction and fixation stability of the proximal humerus fractures: a biomechanical evaluation

Introduction

Bicortical screw fixation, which penetrates and fixes the near and far cortex of bone, has been conventionally used to achieve compressive fixation for fracture using screws. Open reduction and internal fixation using the locking plate are widely used for treating proximal humerus fractures. However, minimal contact between the bone and the locking plate can lead to an insufficient reduction. Theoretically, a dual-lead locking screw with different leads for the screw head and body could enhance the reduction and fixation stability of fragments in proximal humeral fractures without bicortical fixation, and achieve additional compression at the bone-plate-screw interface. This study assessed the insertion mechanics of the lead ratio of the dual-lead locking screw and its effect on the fixation stability of the proximal humerus fracture.

Methods

A Multi-Fix® locking plating system composed of ∅ 3.5 mm locking screws and a locking plate was used to make a locked plating for Sawbone bone blocks and fourth-generation composite humeri. Two different types of Sawbone bone blocks were used to simulate the osteoporotic (10 PCF) and normal cancellous (20 PCF) bones. The lead of the screw head thread (L head ) was 0.8 mm, and that of the screw body (L body ) was 0.8, 1.25, 1.6, 2.0, and 2.4 mm, whose lead ratios (R lead = L body / L head ) were 1.0, 1.56, 2.0, 2.5, and 3.0, respectively.

Results

The dual-lead locking screw elevated the compression between the locking plate and the bone. The elevation in the compression due to the dual-lead thread became weaker for the cancellous bone when the lead of the screw body was more than twice that of the screw head. The plate/humerus compression with strong bone quality withstood higher dual-lead-driven compression.

Discussion

A dual-lead locking screw of L body = 1.25 mm (R lead = 1.56 ) is recommended for maximum rotational stability for the locked humerus plating. The screws with over L body = 1.6 mm (R lead = 2 ) have no advantage in terms of the failure torque and maximum torsional deformation. Any locking dual-lead screw with a body thread lead of <1.6 mm (R lead = 2 ) can be used without the risk of bone crush when surgeons require additional compression to the locked cancellous bone plating.

A Comparison of Anteromedial Plating Versus Anterolateral Plating for Humerus Shaft Fractures Using the Anterolateral Approach

Background Plate osteosynthesis is the gold standard treatment for the management of humeral shaft fractures. In the present study, we performed plate osteosynthesis on the anteromedial and anterolateral surfaces using the anterolateral approach to compare the functional outcomes. Aims and objectives To study and compare the functional outcome, time to achieve union and associated complications of anteromedial and anterolateral plating in humerus shaft fracture by anterolateral approach. Methods This prospective, randomised control study was performed at Dr Baba Saheb Ambedkar Medical College and Hospital, New Delhi, India. This study had 46 patients in total, who were divided into two equal groups at random. All of the fractures in group A were treated using a limited contact dynamic compression plate (LCDCP) on the anterolateral surface using an anterolateral approach, while all of the fractures in group B were corrected using an anteromedial surface using an anterolateral approach using LCDCP. All the patients were followed for six months at regular intervals. At each follow-up, patients were assessed radiologically with X-rays and clinically by Rodriguez-Merchan criteria (RM criteria). Results and conclusions The union was achieved in the majority of the cases of the anteromedial plating group within 12 weeks (78.3%) with a mean union time of 11.7±1.5 weeks than the anterolateral group (56.5%) with a mean union time of 12.3±1.8 weeks. Based on functional assessment according to RM criteria, the excellent outcome was achieved in 69.6% and 65.2% of the anterolateral and anteromedial plating groups, respectively. There was no case of non-union and radial nerve palsy in anteromedial plating cases whereas in anterolateral cases one patient did not achieve union and two (8.7%) had radial nerve injury, which recovered completely by the end of the study. An anterolateral approach with anteromedial surface plating on the flat medial aspect of the humerus is a good technique for fixing humeral fractures.

Biomechanical testing of osteosynthetic locking plates for proximal humeral shaft fractures - a systematic literature review

Proximal humeral shaft fractures can be treated with helically deformed bone plates to reduce the risk of iatrogenic nerve lesion. Controversially to this common surgical technique that was first established in 1999, no biomechanical investigation on humeral helical plating is recorded by other reviews, which focus on proximal fractures exclusively. Does an additional scope for shaft fractures reveal findings of helical testing? The present systematic literature review was performed based on guidelines by Kitchenham et al. to systematically search and synthesize literature regarding biomechanical testing of osteosynthetic systems for proximal humeral shaft fractures. Therefore, a systematic approach to search and screen literature was defined beforehand and applied on the findings of the database PubMed®. Synthesized information of the included literature was categorized, summarized and analyzed via descriptive statistics. Out of 192 findings, 22 publications were included for qualitative synthesis. A wide range of different test methods was identified, leading to a suboptimal comparability of specific results between studies. Overall, 54 biomechanical test scenarios were identified and compared. Physiological based boundary conditions (PB-BC) were referenced in 7 publications only. One study of testing straight and helical dynamic compression plates without PB-BCs was identified, showing significant differences under compressional loading. The absence of test standards of specific fields like humeral fractures lead to a high variance in biomechanical testing of osteosynthetic locking plates for proximal humeral shaft fractures. Physiological approaches offer realistic test scenarios but need to be uniformed for enhanced comparability between studies. The impact of helically deformed locking plates under PB-BC was not identified in literature.

Comparison of Posterior and Anterolateral Surgical Approaches in Treating Adult Humeral Shaft Fractures

AIM

The purpose of this study is to compare the outcomes and complications of two different surgical approaches, the anterolateral and posterior approaches, for treating humeral shaft fractures.

MATERIALS AND METHODS

 Between January 2015 and May 2021, 51 patients with humeral shaft fractures were treated with anterolateral and posterior approaches. Twenty-nine patients were operated with the posterior approach (group 1) and 22 with the anterolateral approach (group 2). Statistical analyses were performed between the two groups regarding age, gender distribution, fractured side, body mass index (BMI), type of trauma, Arbeitsgemeinschaft für Osteosynthesefragen/Orthopaedic Trauma Association (AO/OTA) classification, and follow-up time. Complications such as operative time, amount of bleeding, incision length and implant fracture, radial nerve palsy, wound infection, and nonunion were compared between the two groups. Functional results of the elbow joint were evaluated with the Mayo Elbow Performance Score.

RESULTS

 The mean follow-up period was 49.10±21.15 months (12-75 months) in group 1 and 50.00±23.71 months (range: 15-70 months) in group 2. There was no statistical difference between the groups in terms of age, gender distribution, fractured side, BMI, trauma type, AO/OTA classification, and follow-up time (p>0.05). There was no significant difference between the two groups in terms of operation time, intraoperative bleeding, and incision length (p>0.05). The mean Mayo Elbow Performance Score was 77.24±20.03 (range: 70-100 points) in group 1 and 81.36±8.34 (range: 70-100 points) in group 2, and no significant difference was found (p>0.05). When evaluated in terms of complications, there was no significant difference between the groups (p>0.05). While there was no significant difference between the two groups regarding elbow joint range of motion, the limitation was observed in more patients in group 1.

CONCLUSION

 Similar satisfactory treatment results were obtained in patients who underwent anterolateral and posterior approaches in treating humeral shaft fractures. Furthermore, no difference was found between the two approaches regarding complication rates.

Humeral Shaft Fractures: A Literature Review on Current Treatment Methods

In this review, we aim to provide a concise yet comprehensive summation of the assessment and management of humeral shaft fractures. These are uncommon but prevalent enough that they are part of any trauma surgeon's scope of practice. They have historically been treated using non-operative methods, including braces and casts, supported by published excellent results in the rate of the bone union. However, recently published studies challenge these results and suggest the outcomes might be better with surgery, but the complications of an operation such as infection and nerve injury can not be overlooked. In summary, non-surgical treatment is still the gold standard in the treatment of these fractures, but the indications for surgical management are now clearer and include early signs of delayed union and patients who are unable to have a brace fitted or are uncompliant. It is likely that these new developments will start to change practice, and therefore the treatment of humeral shaft fractures should be a topic of interest of any clinician who deals with them.

Treatment of humeral shaft fractures: a new minimally-invasive plate osteosynthesis versus open reduction and internal fixation: a case control study

Background

To evaluate the feasibility and safety of a new minimally-invasive surgical approach–anteromedial minimally-invasive plate osteosynthesis (MIPO)–in the treatment of middle and distal humeral shaft fractures.

Methods

Fourteen patients with humeral shaft fracture treated with anteromedial MIPO from November 2016 to March 2020 (MIPO Group) were selected as the study subjects. Open reduction and internal fixation (ORIF) were used to treat 14 patients with humeral shaft fractures as the control group (ORIF group). The two groups were fixed with a locking compression plate (LCP) or LCP + multi-directional locking screw system (MDLS). The incision length, intraoperative blood loss, intraoperative fluoroscopy time, operation time, length of hospital stay, fracture healing time, QuickDASH score and Constant score were observed and compared between the two groups.

Results

Fourteen patients were enrolled in each group. The incision length (7.79 ± 2.39 cm), intraoperative blood loss (96.07 ± 14.96 mL), operative time (110.57 ± 21.90 min), hospital stay (6.29 ± 1.49 days) and fracture healing time (14.94 ± 0.99 weeks) in the MIPO group were all lower than those in the ORIF group, and the difference was statistically significant for each parameter (P < 0.05). The intraoperative fluoroscopy time (20.07 ± 3.22) in the MIPO group was significantly higher than that in the ORIF group (P < 0.05). There were no significant differences in age (P = 0.078), QuickDASH score (P = 0.074) or Constant score (P = 0.293) between the two groups and no postoperative complications occurred in any of the patients.

Conclusion

The anteromedial approach MIPO technique has the advantages of less trauma, less bleeding, low risk of nerve injury and high rate of fracture healing. It is one of the most effective methods for the treatment of middle and middle–distal humeral shaft fractures.

Anteromedial Surface Plating for Midshaft Fracture Humerus Through an Anterolateral Approach - A Better Option than Anterolateral Plating

Introduction

Osteosynthesis by plate fixation of humeral shaft fractures as a gold standard for fracture fixation has been proven beyond doubt. However, during conventional anterolateral plating Radial nerve injury may occur which can be avoided by applying plate on the medial flat surface. The aim of this study was to evaluate the results of application of plate on the flat medial surface of humerus rather than the conventional anterolateral surface.

Materials and Methods

This study was conducted between Oct 2010 to Dec 2015. One-hundred-fifty fracture shafts of the humerus were treated with the anteromedial plating through the anterolateral approach.

Results

One-hundred-fifty patients with a fracture shaft of the humerus were treated with anteromedial plating. Twenty were female (mean ±SD,28 years±4.5) and 130 were male (mean ± SD, 38 years±5.6). One hundred and forty-eight out of 150 (98.6%) patients achieved union at 12 months. Two of three patients developed a superficial infection, both of which were treated successfully by antibiotics and one developed a deep infection, which was treated by wound debridement, prolonged antibiotics with the removal of the plate and subsequently by delayed plating and bone grafting.

Conclusion

In the present study, we applied plate on the anteromedial flat surface of humerus using the anterolateral approach. It is an easier and quicker fixation as compared to anterolateral plating because later involved much more dissection than a medial application of the plate and this application of plate on a medial flat surface, does not required Radial nerve exposure and palsy post-operatively. The significant improvement in elbow flexion without brachialis dissection is also a potential benefit of this approach. Based on our results, we recommend the application of an anteromedial plate for treatment of midshaft fractures humerus.

Locking compression plate fixation versus intramedullary nailing of humeral shaft fractures: which one is better? A single-centre prospective randomized study

PURPOSE

To compare the radiological and clinical outcomes of interlocking nail (ILN) and locking plate fixation (LCP) for humeral shaft fractures.

METHODS

A total of 63 patients with displaced humeral shaft fractures between October 2014 and January 2017 were evaluated prospectively. They were divided randomly into two as LCP fixation (group 1) and interlocking nail (ILN) (group 2). Functional outcomes were evaluated using the Disabilities of the Arm, Shoulder, and Hand (DASH), American Shoulder and Elbow Surgeons (ASES), the University of California at Los Angeles (UCLA) shoulder scores, and Short Form-36 (SF-36) questionnaires, and pain was assessed with visual analogue scale (VAS).

RESULTS

After fracture callus was radiologically observed, DASH, ASES, and UCLA scores as well as SF-36 questionnaires and VAS results were noted to have no significant difference between the two groups (p = 0.109, p = 0.082, p = 0.146, p = 0.322, and p = 0.175, respectively). At the last follow-up (post-operative 24 months), the UCLA score was significantly better in group 1 (p = 0.034), whereas VAS result was significantly worse in group 2 (p = 0.017). DASH, ASES scores, and SF-36 questionnaires had no difference (p = 0.193, p = 0.088, p = 0.289). Other parameters revealed no significant differences. Fracture consolidation was observed at a mean of four months in both groups (3 to 7 months in group 1 and 3 to 8 months in group 2) (p = 0.189). Four patients in group 1 and five patients in group 2 underwent surgery for nonunion (p = 0.725). Post-operative radial nerve palsy was seen in one patient in group 2. Two patients in group 1 with superficial infection were treated with antibiotics, and they recovered.

CONCLUSIONS

Regarding our results, the LCP group had significantly better shoulder function than the ILN group, whereas the ILN group had significantly less pain, with similar complication rates. Therefore, both procedures are favourable surgical options for patients with humeral shaft fractures.

Impact of screw thread shape on stress transfer in bone: a finite element study

Gradual screw loosening is a well-known failure mechanism in internal fixation. Loosening is primarily due to progressive bone loss caused by stress shielding, a phenomenon in which a medical device absorbs a disproportionate amount of load within the screw-bone construct. The proximity of elastic moduli of magnesium and bone presents the potential for alleviating screw loosening by allowing optimum stress to be transferred between screw and bone, and in turn, supporting bone remodeling around the screw. In this study, the effect of thread profile on stress transfer in a magnesium fixation was simulated using a 2-D finite element model. Modified stress parameters from a previous study were used to estimate stress transfer across three thread profiles. Results showed highest stress transfer in trapezoidal-shaped magnesium screw thread. In accordance, this study corroborates the potential for magnesium as an ultimate screw material to eliminate progressive screw loosening.

Open reduction and internal fixation of humeral midshaft fractures: anterior versus posterior plate fixation

Background

Fractures of the humeral shaft represent 2–4% of all fractures. Fractures of the humerus have traditionally been approached posteriorly for open reduction and internal fixation. Reports of treating midshaft fractures with an open anterolateral approach and anterior plating are limited. The purpose of this study was to evaluate a series of humeral shaft fractures treated with plate osteosynthesis regarding the effect of the approach and plate location on the healing rate and occurrence of complications.

Methods

We conducted a retrospective chart review of patients aged over 18 years with humeral midshaft fractures treated with anterior or posterior plate fixation. Selection of the approach to the humerus was based on the particular pattern of injury and soft tissue involvement. The minimum follow-up duration was set at six months. The outcomes included the rate of union, primary nerve palsy recovery, secondary nerve damage, infection and revision surgery.

Results

Between 2006 and 2014, 58 patients (mean age, 59.9; range, 19–97 years) with humeral midshaft fractures were treated with anterior (n = 33) or posterior (n = 25) plate fixation. After a mean follow-up duration of 34 months, 57 of 58 fractures achieved union after index procedure. Twelve fractures were associated with primary radial nerve palsy. Ten of the twelve patients with primary radial palsy recovered completely within six months after the index surgery. In total, one patient developed secondary palsy after anterior plating, and three patients developed secondary palsy after posterior plating. No significant difference in the healing rate (p = 0.4), primary nerve palsy recovery rate (p = 0.6) or prevalence of secondary nerve palsy (p = 0.4) was found between the two clinical groups. No cases of infection after plate fixation were documented.

Conclusions

Open reduction and internal fixation using an anterior approach with plate fixation provides a safe alternative to posterior plating in the treatment of humeral shaft fractures. An anterior approach allows supine positioning of the patient and yields union and complication rates comparable to those of a posterior approach with plate fixation for the treatment of humeral shaft fractures.

Anteromedial minimally invasive plate osteosynthesis (MIPO) for distal third humeral shaft fractures - Is it possible?: A cadaveric study

INTRODUCTION

The purpose of this study was to evaluate the feasibility of the anteromedial minimally invasive plate osteosynthesis (MIPO) approach for distal third humeral shaft fractures and identify neurovascular structures at risk with this approach.

METHODS

Twenty cadaveric arms were fixed with 12-hole precontoured narrow locking compression plates (LCP) with the anteromedial approach using MIPO technique. The proximal approach was done between the biceps and deltoid muscle directly to the bone. The distal approach involved elevating the brachialis from medial intermuscular septum. The plate was inserted beneath the brachialis tunnel from distal to proximal. Three locking screws were fixed at each end through incisions and the rest of screws were inserted percutaneously. The arms were then dissected to identify damage to or direct contact between the screws and brachial artery (BA), median nerve (MN), musculocutaneous nerve (MCN), and radial nerve (RN). The distances from the screws to structures at risk, humeral length, and length of three distal screws in mediolateral (ML) direction were measured.

RESULTS

The average humeral length was 28.97 cm. The average danger zone for the BA and MN were 20.47%-62.66% of the humeral length from the lateral epicondyle, and 20.47%-75.02% for the MCN. The ulnar nerve was not endangered by this approach as it lies posteromedially to the humerus. The danger zone for the RN averaged 27.07%-43.74%, and the most dangerous screw that either penetrated or touched the nerve was at the fifth hole, which lay at 33.14% of the humeral length. The average length of three distal screws in ML direction were 41.4, 25.0 and 22.5 mm.

CONCLUSIONS

The anteromedial MIPO approach can be performed through the internervous plane beneath the brachialis muscle without exposing any nerves or causing any muscle splitting with a 12-hole plate. Both proximal and distal screw insertion must be done with direct exposure. Insertion of percutaneous screws in the middle part of the plate between the two incisions is not possible. This approach could be an alternative for extra-articular distal third humeral shaft fractures which provides less invasive surgical dissection, allows the use of longer distal screws, and achieves better cosmesis.