The authors performed an ultrasound assessment of 46 distal radius fractures that were treated with palmar locking plates at an average follow-up period of 18 months (range, 6 to 43 months). Of the total 230 locking screws in the distal limb of the plate, 59 screws were found to protrude through the dorsal cortex by 0.5 mm or more (range 0.5 – 6.1 mm). Asymptomatic extensor tenosynovitis was detected in association with 4 prominent screws and symptomatic extensor tenosynovitis was detected in association with 14 prominent screws. The authors opined that distal screw penetration greater than 1.5 mm in the 3rd and 4th compartments may cause problems.
Evaluation of distal locking screw placement with standard radiographs and fluoroscopy may not provide a precise assessment of dorsal cortical penetration due to the irregular shape of the distal radius. Surgeons may find it necessary in some cases to purposely capture the dorsal cortex with screws for adequate fracture stability. However, in most cases, dorsal cortical penetration is not necessary with locking implants and thus surgeons should “size down” from what is measured distally in most cases. Uncertainty remains about what length of screw prominence is sufficient to irritate extensor tendons and about the duration of irritation needed to cause rupture (Thomas and Greenberg, JHS Am 2009). In cases of suspected extensor tendon irritation, ultrasound may be a valuable tool in assessing for screw/peg prominence and tendon pathology.