Distal locking screw length for volar locking plate fixation of distal radius fractures: Postoperative stability of full-length unicortical versus shorter screws

Evaluation of Unicortical Locking Screw Placement for Torsional Loads in Distal Radius Fractures: A Biomechanical Study in Cadavers

Background We aimed to compare bio-mechanical outcomes of short-length 75%-length uni-cortical screw (SL75UCS) and full-length 100%-length screws (FL100S) under axial compression (AXC) and torsional compression (TRC) in cadaveric distal radius volar plate model. Methodology A total of 20 wrists from 10 fresh frozen cadavers were included. A 2.5 mm titanium alloy distal radius anatomical plate was placed to the distal radii in full anatomical position, just proximal to the watershed line. Three bi-cortical screws to the shaft of the radius, followed by uni-cortical drilling for distal screwing were placed. Measurement by pulling the drill once it reached the opposite cortex was applied. We selected the screw lengths such that they corresponded to the SL75UCS. In the same configuration for each of the cadavers, we delivered six screws from distal radius holes of the anatomical plate. An oscillating handsaw was used to create an extra-articular distal radius fracture model (AO 23-A3.2). We created a dorsal AP model by performing a 1-cm wedge osteotomy from the dorsal aspect. Complete separation of the volar cortex was achieved. Potting was performed by embedding the shaft of the prepared radius into the polyurethane medium. We placed aluminum apparatus into the distal end to ensure applying of AXC and TRC in bio-mechanistic tests. Results No statistically significant difference of stiffness between the SL75UCS and FL100S both under AXC (p=0.88) and TRC (p=0.82). SL75UCS and FL100S groups did not differ in elastic limit under AXC (p=0.71) and TRC (p=0.71). Maximal force on SL75UCS and FL100S groups were also similar under both AXC (p=0.71) and TRC (p=0.50). Conclusions Our study findings suggest that drilling the dorsal cortex may not be necessary in the management of distal radius fractures. Instead, utilizing SL75UCS could serve as a viable alternative. This approach offers potential advantages in reducing the risk of extensor tendon complications associated with drilling or screw protrusion. It is a safe method under torsional load to avoid drilling of the dorsal cortex and SL75UCS could be performed in order to prevent from extensor tendon complications secondary to drilling or screw protrusion.

Optimal screw length in volar locking plate osteosynthesis for distal radius fractures: a systematic review

BACKGROUND

Fractures of the distal radius represent the most common fracture of the upper limb, and can be managed surgically with volar locking plate osteosynthesis (VLPO). Uncertainty remains regarding the optimal length of the distal locking screws. The aim of this study was to determine the optimal VLPO screw length which provided adequate stability while minimizing complications.

METHODS

A systematic review of relevant literature published within Cochrane, PubMed, MEDLINE and Embase, including studies up to April 2020, was performed using the Preferred Reporting Items for Systemic Reviews and Meta-analysis (PRISMA) guidelines. Studies were included if they investigated distal radius fracture fixation with VLPO, screw lengths, complications, and associated imaging.

RESULTS

Search results identified 664 relevant studies, of which 14 studies examining 926 radii were included for review. Synthesis revealed that unicortical locking fixation with screws ~75% the depth of the radius, or 2 mm short of the dorsal cortex, provided equivalent stability to bicortical fixation. The lunate may be used as a proxy to determine radial depth at each quartile column. Inadvertent screw protrusion can be assessed by taking four images intra-operatively; anteroposterior (AP), lateral, 45° supinated and dorsal tangential views (DTVs). Radial shaft screws can have up to 2 mm prominence with no clinical significance.

CONCLUSION

Unicortical locking fixation at least 75% the depth of the distal radius provides equivalent stability to bicortical fixation in extra-articular fractures with lower complication rates. Imaging should be used to confirm that penetration of the dorsal cortex has not occurred.

Systematic use of short unicortical epiphyseal locking screws versus full-length unicortical locking screws in distal radius fracture volar plating: A prospective and comparative study

PURPOSE

Volar locking plates, used in distal radius fracture (DRF), present a risk of injuring extensor tendons with screws penetrating the dorsal cortex of the radius. Actually, even when aiming to use maximum-length unicortical locking screws, some still could be bicortical. We hypothesize the use of only short unicortical screws would allow a proper stabilization of the radial epiphysis without the risk of dorsal cortex penetration.

MATERIALS AND METHODS

A prospective monocentric non-randomized study was conducted. Patients with DRF (excepted for partial dorsal joint fractures) were treated in group A with short locking epiphyseal screws (16 mm for females, 18 mm for males) and in group B with full-length unicortical locking screws. Ultrasound was done 3 months postoperatively to evaluate the number and length of prominent dorsal screws. X-rays were performed after 6 weeks to assess stability according to volar tilt and radial inclination variations.

RESULTS

There were 37 patients in group A and 39 in group B with 148 and 156 epiphyseal screws, respectively. In group A, there were 0% of dorsal penetrating screws against 6.5% (10 screws from 8 patients) in group B (p < 0.05). There was no significant difference for the stability between the groups: mean volar tilt variation ( - 0.6° vs. - 0.7°) and mean radial inclination variation ( - 0.4° vs. - 0.4°).

CONCLUSION

For a same stability with volar locking plates for DRF, short epiphyseal locking screws should be preferred to full-length unicortical screws in order to prevent extensor tendon injuries. Based on 75% of distal radial average anteroposterior width for each sex, screw lengths of 16 mm for females and 18 mm for males seem to be the length to use. LEVEL OF EVIDENCE 2: Prospective, Comparisons made, non-randomized.