New knowledge about the molecular biology of fracture-healing provides opportunities for intervention and reduction of risk for specific phases that are affected by disease and medications. Modifiable and nonmodifiable risk factors can prolong healing, and the informed clinician should optimize each patient to provide the best chance for union. Techniques to monitor progression of fracture-healing have not changed substantially over time; new objective modalities are needed.

Background: The aim of this study was to quantify the stabilizing properties of a 3-dimensional (3D)-printed short-arm cast and compare those properties with traditional fiberglass casts in a cadaveric subacute distal radius fracture model. Methods: A cadaveric subacute fracture model was created in 8 pairs of forearms. The specimens were equally allocated to a fiberglass cast or 3D-printed cast group. All specimens were subjected to 3 biomechanical testing modalities simulating daily life use: flexion and extension of digits, pronation and supination of the hand, and 3-point bending. Between each loading modality, radiological evaluation of the specimens was performed to evaluate possible interval displacement. Interfragmentary motion was quantified using a 3D motion-tracking system. Results: Radiographic assessment did not reveal statistically significant differences in radiographic parameters between the 2 groups before and after biomechanical testing. A statistically significant difference in interfragmentary motion was calculated with the 3-point bending test, with a mean difference of 0.44 (±0.48) mm of motion. Conclusions: A statistically significant difference in interfragmentary motion between the 2 casting groups was only identified in 3-point bending. However, the clinical relevance of this motion remains unclear as the absolute motion is less than 1 mm. The results of this study show noninferiority of the 3D-printed casts compared with the traditional fiberglass casts in immobilizing a subacute distal radius fracture model. These results support the execution of a prospective randomized clinical trial comparing both casting techniques.

Objectives

To use a novel, validated bioassay to monitor serum concentrations of a breakdown product of collagen X in a prospective longitudinal study of patients sustaining isolated tibial plateau fractures. Collagen X is the hallmark extracellular matrix protein present during conversion of soft, cartilaginous callus to bone during endochondral repair. Previous preclinical and clinical studies demonstrated a distinct peak in collagen X biomarker (CXM) bioassay levels after long bone fractures.

Setting

Level 1 academic trauma facility.

Patients/participants

Thirty-six patients; isolated tibial plateau fractures.

Intervention

(3) Closed treatment, ex-fix (temporizing/definitive), and open reduction internal fixation.

Main outcome measurements

Collagen X serum biomarker levels (CXM bioassay).

Results

Twenty-two men and 14 women (average age: 46.3 y; 22.6-73.4, SD 13.3) enrolled (16 unicondylar and 20 bicondylar fractures). Twenty-five patients (72.2%) were treated operatively, including 12 (33.3%) provisionally or definitively treated by ex-fix. No difference was found in peak CXM values between sexes or age. Patients demonstrated peak expression near 1000 pg/mL (average: male-986.5 pg/mL, SD 369; female-953.2 pg/mL, SD 576). There was no difference in peak CXM by treatment protocol, external fixator use, or fracture severity (Schatzker). Patients treated with external fixation (P = 0.05) or staged open reduction internal fixation (P = 0.046) critically demonstrated delayed peaks.

Conclusions

Pilot analysis demonstrates a strong CXM peak after fractures commensurate with previous preclinical and clinical studies, which was delayed with staged fixation. This may represent the consequence of delayed construct loading. Further validation requires larger cohorts and long-term follow-up. Collagen X may provide an opportunity to support prospective interventional studies testing novel orthobiologics or fixation techniques.

Level of evidence

Level II, prospective clinical observational study.

Introduction

The modified Radiographic Union Score for Tibia (RUST) fractures was developed to better describe fracture healing, but its utility in resource-limited settings is poorly understood. This study aimed to determine the validity of mRUST scores in evaluating fracture healing in diaphyseal femur fractures treated operatively at a single tertiary referral hospital in Tanzania.

Methods

Radiographs of 297 fractures were evaluated using the mRUST score and compared with outcomes including revision surgery and EuroQol five dimensions questionnaire (EQ-5D) and visual analog scale (VAS) quality-of-life measures. Convergent validity was assessed by correlating mRUST scores with EQ-5D and VAS scores. Divergent validity was assessed by comparing mRUST scores in patients based on revision surgery status.

Results

The mRUST score had moderate correlation (Spearman correlation coefficient 0.40) with EQ-5D scores and weak correlation (Spearman correlation coefficient 0.320) with VAS scores. Compared with patients who required revision surgery, patients who did not require revision surgery had higher RUST scores at all time points, with statistically significant differences at 3 months (2.02, P < 0.05).

Discussion

These results demonstrate that the mRUST score is a valid method of evaluating the healing of femoral shaft fractures in resource-limited settings, with high interrater reliability, correlation with widely used quality of life measures (EQ-5D and VAS), and expected divergence in the setting of complications requiring revision surgery.