External fixator-assisted versus -unassisted open reduction and internal fixation of intraarticular distal radius fractures.

Distal radius fractures (DRFs) are among the most frequent injuries presenting in the emergency room (ER) and account for approximately 15% of all fractures in adults. Multiple modalities for surgical fixation of DRFs are available: percutaneous Kirschner wires fixation, external fixators, volar or dorsal plates (locking or conventional), or a combination of these techniques. This is amplified for the AO subtypes B and C DRFs which are intraarticular in nature and may pose significant challenges with added comminution and disruption of the articular surface.

External fixators may be utilized temporarily to achieve and maintain intraarticular fracture reduction while the fracture is fixed definitively using internal fixation devices – ‘external fixation-assisted fracture reduction; this technique leverages ligamentotaxis to indirectly reduce fracture fragments, facilitating controlled and minimally invasive manipulation during internal fixation. The National Aeronautics and Space Administration Task Load Index (NASA TLX) was developed to evaluate subjective experience following aviation simulations. It has since been validated as an effective instrument for assessing surgeon workload across various surgical fields and is recognized as an effective tool to measure surgeons’ intraoperative physical and cognitive workload.

We propose to use the external fixation-assisted fracture reduction – wherein ligamentotaxis will be used to indirectly reduce fracture fragments, facilitating controlled and minimally invasive manipulation during internal fixation. This technique may allow us to achieve better articular reduction thereby achieve better functional and radiological outcomes.

Primary objectives

1. To compare the articular reduction of external fixator assisted versus unassisted ORIF of intraarticular (AO fracture subtypes B and C) DRFs in the postoperative radiographs.

2. To compare the functional outcomes of external fixator assisted versus unassisted ORIF of intraarticular (AO fracture subtypes B and C) distal radius fractures at six-month follow-up using QuickDASH and PRWE scores.

Secondary objectives

1. To quantify and compare the workload endured by the surgeon in performing the surgical procedures using the National Aeronautics and Space Administration Task Load Index (NASA TLX).

2. To compare the range of motion in wrist flexion and extension, forearm pronation and supination, and grip strength with contralateral side.

3. To study the pattern of intraarticular fracture lines on the preoperative CT scans of the wrist.

Study Design

Randomised, open-label, comparative, two-arm parallel study; randomization will be done using the maximum tolerated imbalance technique.

Methodology for primary objective 1:

Radiographs of the wrist are routinely taken as part of the fracture treatment protocol in the postoperative period usually when the patient is pain-free and comfortable to be transferred to the radiology department. The articular reduction of the distal radius would be determined on the posteroanterior and lateral digital radiographs of the wrist with a marker of a predetermined size. Any gap or step in the articular surface would be measured using a scale with 0.5 mm graduation.

Methodology for primary objective 2:

QuickDASH and PRWE scores would be obtained using the QuickDASH and PRWE questionnaires at the six-month follow-up following DRF treatment.

Methodology for secondary objective - 1

To quantify the workload endured by the surgeon while performing the surgical procedure, the NASA Task Load Index questionnaire would be administered to the surgeon after every surgery. This index would help document and compare the subjective technical difficulty of the procedure as felt by the surgeon.

Methodology for secondary objective - 2

At the time of 6-month follow-up, wrist flexion and extension, forearm pronation and supination would be measured on both upper limbs. Grip strength would be measured using hand dynamometer.

Methodology for secondary objective - 3

To study if the intraarticular fractures getting enrolled follow any classifiable pattern, the fracture lines at the articular surface of the distal radius in the axial section would be documented on a 3D model of the distal radius. This will be done using computer software.

Study Setting

Department of Orthopaedics, All India Institute of Medical Sciences, Bhopal

Study Participants

Patients with AO fracture subtypes B and C of the distal radius will be assessed. All patients having unstable fracture pattern i.e., more than 2 mm of step-off/gap in the articular surface, a dorsal tilt more than 15°, radial inclination less than 15°, or radial shortening more than 5 mm would be advised operative management for the fracture and would be approached for participation in the study. CT scan of the wrist would be performed as part of the routine DRF management protocol.

Sample Size Calculation:

For radiological outcome – articular reduction assessed in the postoperative radiographs.

The MCID for intraarticular fracture reduction post-DRF surgery is 0.5mm with SD of 0.7.

Required sample 31per group; adding 10% attrition: 35 per group (total 70).

For functional outcome assessed using QuickDASH score:

The minimum clinically important difference (MCID) for QuickDASH score post-DRF surgery is 16.

Required sample 14 per group; adding 10% attrition: 16 per group (total 32)

For functional outcome assessed using PRWE score.

The MCID for PRWE score post-DRF surgery is 11.5 with area under the curve being 0.71 (95% CI, 0.57–0.85) for the function subscale.

Required sample 32 per group; adding 10% attrition: 36 per group (total 72).

Complications

Any complication encountered during treatment and follow up will be recorded:

Loss of reduction

Superficial radial nerve injury

DRUJ pain/ instability

Reflex sympathetic dystrophy

Intervention arm

The patient will be prepared in the usual way for surgery. External fixator will be applied intraoperatively – two pins in the radial shaft and two pins in the second metacarpal. Small skin incisions will be placed before the pins are inserted. Image-intensifier will be used to aid correct pin placement and subsequent fracture reduction by manipulation. Attempt would be made to obtain acceptable reduction of the articular fragments. Distal radius plate(s) will be selected depending on the fracture configuration. Reduction of the intraarticular as metaphyseal fragments will be checked under image intensifier control. DRUJ stability will be assessed. In case of ulnar styloid fracture displacement with DRUJ instability - the ulnar styloid will be fixed with tension band wiring technique.

Once the plate has been applied, the external fixator will be removed. A plaster of Paris slab will be applied postoperatively. This will be kept for two weeks. Hand elevation will be done. Finger, elbow and shoulder mobilisation will be commenced immediately in the postoperative period. Wrist and forearm mobilisation will be commenced after plaster slab removal.

Control arm

All procedures would be the same except the use of external fixator.

Statistical Analysis

All statistical analysis will be carried out using Microsoft Excel or JASP software. All continuous variables will be reported as means and standard deviations (SD) or as median and interquartile range (IQR) after assessing the normality of the data. Descriptive statistics will be used for assessing demographic and clinical data. Intention to treat analysis would be done and reported.

• Normality will be checked for all continuous variables (Shapiro-Wilk test). If distribution is not normal, non-parametric Mann-Whitney U will be used.

• Categorical adverse events or complications (if any) would be compared using chi-squared or Fisher’s exact test.

• Covariate adjustment (baseline/preoperative value) may be performed using analysis of covariance (ANCOVA) for functional outcomes.

• Effect sizes (mean differences with 95% confidence intervals) would be reported.

• Where measures are compared to the contralateral side, ratios or percentage of normal can be calculated and analyzed.