Effect of Fibular Allograft Augmentation in Medial Column Comminuted Proximal Humeral Fractures: A Randomized Controlled Trial

Predicting functional outcome after nonoperative treatment of proximal humeral fractures involving the surgical neck

BACKGROUND

In nonoperative treated proximal humeral fractures (PHFs), uncertainty remains regarding functional outcome. Therefore, the aim was to identify predictors of functional outcome following nonoperative treatment of PHF and to develop predictive models.

METHODS

Adults with a nonoperatively treated PHF involving the surgical neck were followed for 1 year. Radiographic parameters included fracture configuration, displacement, bone quality, and the critical shoulder angle. The neck-shaft angle and humeral head offset assessed displacement. The greater tuberosity index (GTI) addressed greater tuberosity (GT) displacement relative to the articular surface while the impingement index addressed GT-displacement relative to the acromion. Multivariate regression models determined predictors of impaired function as measured by Constant score (CS), flexion, and external rotation (ER). Recursive partitioning created a decision tree model over dichotomized functional outcome that combined flexion and ER (good = flexion ≥120° and ER ≥ 40°).

RESULTS

In 272 consecutive patients (mean age: 66 years, 69% women and 31% men), mean functional outcomes were a CS of 74 points, 138° flexion, and 50° ER. Older age was a predictor for impaired CS, flexion, and ER (P < .001), while sex only influenced CS (P = .040). Every 10% increase in GTI assessed on the Y-view explained a decrease of 3 CS points, 7° of flexion, and 5° of ER (P < .001). Every 10° of varus angulation assessed on anterior-posterior views in internal rotation resulted in a decrease of 1 CS point and 4° of flexion (P ≤ .004). Subgroups of combined important GT-displacement (GTI ≥1.15) with age >76 years or < 119° varus angulation demonstrated the worst function. Linear prediction models estimated flexion, ER, and CS with a mean difference of 10°, 3°, and 3 points, respectively. The decision tree model predicted good function with 80% accuracy (positive predictive value = 81%; negative predictive value = 78%).

CONCLUSION

Demographic and radiographic predictors were identified allowing for accurate functional prognosis of nonoperatively treated PHF involving the surgical neck. A combined assessment of the anterior-posterior-view in internal rotation and Y-view is sufficient for accurate function prediction. The identified subgroups resulting in good or impaired function and the predictive models may be useful for patient counseling and guidance of treatment-related expectations.

Factors associated with failure of locking plate fixation in proximal humerus fractures

BACKGROUND

Locking plate fixation remains the mainstay of surgical fixation of unstable proximal humerus fractures, however rates of failure remain high. The aim of this study was to identify risk factors that could be used to predict the likelihood of fixation failure.

METHOD

Patients with proximal humerus fractures managed with locking plate fixation between 2010 and 2019 at a Level 1 trauma centre were included. Radiographs were evaluated for parameters that could be used to predict failure of fixation. Pre-operative factors included were the Neer classification, cephalomedullary angle, medial calcar length, disruption of the medial hinge, and anatomical neck fracture. Post-operative factors included the cephalomedullary angle, medial calcar reduction gap, presence of anatomical tuberosity reduction, presence of medial calcar screws, screw distance to articular surface, and number of screws present in the humeral head.

RESULTS

There were 189 patients included; 54 % male, mean age 49.9 (intact fixation) group and 56.1 (failure). The rate of fixation failure was 22 %. Factors associated with increased risk of failure following multivariable analysis included increasing age (OR 1.04 per year, CI 1.01-1.07), varus pre-operative cephalomedullary angle (OR 2.84, CI 1.03-7.83), and non-anatomical calcar reduction (OR 2.31, CI 1.05-5.08). The presence of calcar screws was associated with decreased risk of fixation failure (OR 0.30, CI 0.10-0.90). This analysis was used to create a predictive model including the Neer classification, age, pre-operative cephalomedullary angle, post-operative cephalomedullary angle, anatomic reduction of the medial calcar, and presence of medial calcar screws.

CONCLUSION

Rates of locking plate fixation failure in proximal humerus fractures remain high. This study has identified key pre-operative and intra/post-operative factors that can be used to predict the risk of failure. Further work is required to validate this model.

LEVEL OF EVIDENCE

Level II.

Bone grafting augmentation choices in complex proximal humerus fractures: A systematic review

Objective

To systematically identify and evaluate different bone graft augmentation techniques in the operative treatment of complex proximal humerus fractures.

Methods

Four databases were searched from 1970 to February 2023 for Level I to IV English studies that investigated outcomes of different bone augments in the primary surgical fixation of proximal humerus fractures. The JBI critical appraisal checklist, methodological index for non-randomized studies and cochrane risk of bias tool were used to assess study quality. Descriptive statistics including weighted means are presented where applicable.

Methods

Thirty-three articles including 964 patients met the inclusion. Seven bone augments were identified, including fibular strut allograft (693 patients across 21 studies), femoral head allograft (84 patients across 4 studies), iliac crest allograft (54 patients across 3 studies), iliac crest autograft (94 patients across 5 studies), humeral endosteal allograft (6 patients in 1 single study), unspecified cancellous allograft (28 patients in 1 single study) and distal clavicle autograft (3 patients in 1 single study). Mean patient age was 67.1 years, with female patients comprising 65.2 %. Fracture union rates were similar between groups, with an average of 99.6 %. The average Constant Murley Score (CMS) was not reported in the humeral endosteal allograft or the distal clavicle autograft group but was 81.8 (fibular strut allograft), 79.1 (femoral head allograft), 76.8 (iliac crest allograft), 77.7 (iliac crest autograft), and 81.5 (unspecified cancellous allograft) in the remaining groups. Revision surgery was required in 16.7 % of patients receiving humeral endosteal allograft, 7 % of patients with femoral head allograft, 2 % of iliac crest autografts and 1.9 % in the fibular allograft group. Reported complications included avascular necrosis, hardware complications and loss of reduction.

Conclusion

Bone graft augmentation is an effective adjunct to open reduction internal fixation of complex proximal humerus fractures. Fibular strut allograft is the most common bone graft augment used. Majority of patients treated with bone graft augmentation achieved bony union (83%-100 %) and average CMS scores at final follow-up were similar between graft types (76-82). However, no conclusive data suggests superiority of one bone graft type over another. Future studies should aim to compare the outcomes amongst graft types.

Biomechanical study of two different fixation methods for the treatment of Neer III proximal humerus fractures

BACKGROUND

The lateral locking plate for the proximal humerus is currently the most commonly used surgical procedure for the treatment of elderly proximal humeral comminuted fractures. Previous studies have found that the rate of postoperative complications in patients of proximal humerus fractures with medial column involvement is relatively high. Through biomechanical methods, this study aims to investigate the effectiveness of the conventional lateral locking plate fixation along with the addition of the metacarpal supporting plate on the medial column in the treatment for proximal humeral fractures involving the medial column. The goal is to reduce the rate of postoperative internal fixation failure in patients with medial column injury.

METHODS

Thirty artificial synthetic humerus models are used as experimental samples. A proximal humerus fracture model with medial column injury was created, and then divided into two groups. Group A was fixed with a proximal humerus lateral locking plate (single-plate group). Group B was fixed with a proximal humerus lateral locking plate and a metacarpal supporting plate on the medial column (double-plate group). The failure displacement, stiffness, and strength of the repaired proximal humerus fractures with two different methods were tested under compression at posterior extension of 15°, forward flexion of 15°, and vertical direction.

RESULTS

There was no statistical significance in the comparison of the failure displacement of repaired proximal humeral fractures between the two groups under compression at posterior extension of 15° and forward flexion of 15° (P > 0.05). However, the failure displacement of the fracture was longer in single-plate group than in double-plate group under compression at vertical direction (P < 0.05). The double-plate group was better in terms of biomechanical stiffness and strength compared to the single-plate group at all three testing angles (P < 0.05).

CONCLUSIONS

For patients whose proximal humeral fractures involve the medial column, the addition of a support plate on the medial side of the humerus is recommended along with the lateral locking plate. The double-plate strategy can increase the stability of the medial column of the proximal humerus, and enhance the overall biomechanical property of the repaired proximal humerus.

Lateral Wall Integrity of the Greater Tuberosity Is Important for the Stability of Osteoporotic Proximal Humeral Fractures After Plate Fixation

BACKGROUND

Previous studies assessing surgical fixation of osteoporotic proximal humeral fractures have primarily focused on medial calcar support. In this study, we utilized a specific model for 2-part surgical neck fracture of the osteoporotic proximal humerus to investigate how severe comminution of the greater tuberosity (GT) lateral wall affects biomechanical stability after fixation with a plate.

METHODS

Ten matched pairs of cadaveric humeri (right and left) were assigned to either a surgical neck fracture alone (the SN group) or a surgical neck fracture with GT lateral wall comminution (the LW group) with use of block randomization. We removed 5 mm of the lateral wall of the GT to simulate severe comminution of the lateral wall. Axial compression stiffness, torsional stiffness, varus bending stiffness, and the single load to failure in varus bending were measured for all plate-bone constructs.

RESULTS

Compared with the SN group, the LW group showed a significant decrease in all measures, including torsional stiffness (internal, p = 0.007; external, p = 0.007), axial compression stiffness (p = 0.002), and varus bending stiffness (p = 0.007). In addition, the mean single load to failure in varus bending for the LW group was 62% lower than that for the SN group (p = 0.005).

CONCLUSIONS

Severe comminution of the GT lateral wall significantly compromised the biomechanical stability of osteoporotic, comminuted humeral surgical neck fractures.

CLINICAL RELEVANCE

Although the generalizability of this cadaveric model may be limited to the extreme clinical scenario, the model showed that severe comminution of the GT lateral wall significantly compromised the stability of osteoporotic humeral surgical neck fractures fixed with a plate and screws alone.

Fibula allograft in complex three-part and four-part proximal humeral fractures in active patients, a matched case-control study

Background

About 20% of proximal humerus fractures (PHFs) are unstable and/or markedly displaced and therefore require surgery. Locking plate fixation after anatomical reduction has become the current treatment of choice for these fractures in the active population. However, studies have shown complication rates up to 36%, such as loss of reduction and avascular necrosis. To date, data from literature are inconclusive on outcomes following the use of an intramedullary fibula allograft in PHFs, possibly due to the case mix. It is hypothesized that the use of a fibula allograft is beneficial to prevent secondary displacement of the fracture in cases where the medial hinge is markedly displaced and unstable, resulting in better clinical and patient reported outcomes.

Methods

In this multicenter matched cohort study, patients with an unstable, displaced PHF, including anatomic neck fractures and significantly displaced surgical neck fractures, were included. Patients that were treated with a locking plate augmented with a fibula allograft were matched to patients who had undergone locking plate reconstruction without the allograft. The matches were made based on fracture characteristics, age, and performance status. Functional outcomes, Patient Reported Outcome Measures, complications, and radiographic results were compared.

Results

Twelve patients with fibula allograft augmented osteosyntheses were included and matched to 12 control patients. The mean age was 58 years in the fibula allograft group compared to 62 years in the control group. Minimum follow-up was 12 months. Disability of the Arm Shoulder and Hand score, Constant Shoulder score, abduction, and external rotation were significantly better in the fibula allograft group (17.4 ± 8.6 vs. 26.1 ± 19.2, P = .048; 16.5 ± 11.5 vs. 19.8 ± 16.5 P = .040; mean 127° ± 38° vs. mean 92° ± 49° P = -.045; 50° ± 21° vs. mean 26° ± 23°, P = .004). There was no statistically significant difference in the Oxford Shoulder score between groups (P = .105). The Visual Analog Scale was not significantly different between groups (3.1 ± 1.8 vs. 1.6 ± 1.9, P = .439). Radiographic union was reached in 11 patients of the fibula allograft group compared to 8 in the control group (P = .317). The complication rate was twice as high in the control group (3 vs. 7).

Conclusion

Additional support of the medial hinge in unstable PHFs with a locking plate in combination with a fibula allograft appears to create a more stable construct without compromising the viability of the articular surface of the head. The use of a fibula allograft in selected complex cases could therefore result in better clinical outcomes with lower complication rates.

Current concepts of bone grafting in trauma surgery

Bone graft in trauma surgery is commonly used in managing bone defects, non-union, fracture related infections, arthrodesis or to provide structural support in fractures. A variety of bone grafts are made available to the treating physician, which includes autograft, allograft and bone graft substitutes. The future of bone grafting in trauma surgery is exciting with the incorporation of technological advancement such as gene therapy, 3D-printing and tissue engineering. Regardless, there are still limitations to what we understand regarding current bone grafting techniques with conflicting literature on their clinical utility and indication. The aim of this review article therefore is to take a step back and critically evaluate the current concepts of bone grafting in trauma surgery, with special emphasis made on reviewing the types of bone graft, biology of bone graft incorporation and indication for its use in various clinical scenarios.