Abstract

Ulnocarpal impaction (UCI) is a common cause of ulnar-sided wrist pain. UCI typically occurs in wrists with positive ulnar variance, which causes altered loading mechanics between the ulnar head, lunate and triquetrum. However, many individuals with positive ulnar variance never develop UCI, and some with neutral or negative ulnar variance do experience UCI. This suggests that other variables contribute to the development of UCI. Suspected culprits include lunate morphology, and dynamic changes with loaded (grip) pronation. If these anatomic variations are contributing to UCI, we expect them to influence functional impairment scores. Therefore, the objective of this study was to evaluate the relationship between radiographic parameters and pre-surgical upper extremity patient-rated outcomes scores (PROS) in patients with a diagnosis of UCI.

Retrospective cohort study of patients undergoing ulnar shortening osteotomy or arthroscopic wafer procedure for UCI. Data derived from prospectively collected departmental database that captured demographic, clinical, functional and radiographic information. Radiographic parameters evaluated were: lunate morphology [presence vs. absence of hamate facet; Antuna-Zapico (A-Z) classification], and dynamic changes on grip view [difference in lunate-ulnar head distance (LUD); difference in lunate uncovering index (LUI)]. PROS assessed were QuickDASH and Patient-Rated Wrist Evaluation (PRWE) scores, collected at patient enrolment. ANOVA was used to assess for differences in PROS between A-Z classification groups. Student's t-test was used to assess for differences in PROS based on presence/absence of a hamate facet. Regression analysis evaluated a relationship between change in LUD with grip and PROS, and change in LUI with grip and PROS.

Preliminary analysis included 23 wrists, with a mean patient age of 48.9 years [standard deviation (SD) 14.5 years]. Forty-eight percent were male, and the dominant limb was involved in 52.2% of cases. Average QuickDASH and PRWE scores at enrolment were 50.9 (SD 22.2) and 62.2 (SD 22.0), respectively. Assessment of radiographs revealed 17 patients (73.9%) without a hamate facet. Five patients (21.7%) had A-Z Type I lunate morphology, and nine (39.1%) had Type II and Type III morphology, respectively. ANOVA revealed no differences in enrolment QuickDASH (p = 0.185) or PRWE (p = 0.256) scores between A-Z classification groups. Similarly, Student's t-test found no difference based on presence/absence of a hamate facet (QuickDASH p = 0.594; PRWE p = 0.573). Regression analysis revealed no relationship between change in LUD with grip and PROS (QuickDash R2 = 0.020, p = 0.619; PRWE R2 = 0.009, p = 0.733), and no relationship between change in LUI with grip and PROS (QuickDash R2 = 0.000, p = 0.913; PRWE R2 = 0.010, p = 0.722).

Preliminary results suggest no relationship between A-Z classification lunate morphology, presence/absence of a hamate facet, change in LUD, or change in LUI and pre-surgical PROS. It is unclear if our findings represent the true relationship between these radiographic parameters and PROS, or reflect our preliminary sample size. Data analysis is ongoing to add clarity to this question.