Can CT-Scan Measurements of Humpback Deformity, Dislocation, and the Size of Bony Cysts Predict Union after Surgery for Scaphoid Nonunion?

Abstract

Objective Scaphoid fractures are associated with high rates of late- or nonunion after conservative treatment. Nonunion is reported to occur in approximately 10% of all scaphoid fractures. It is known that the union of scaphoid fractures is affected by factors such as location at proximal pole, tobacco smoking, and the time from injury to treatment. Same factors seem to affect the healing after surgery for scaphoid nonunion. While the impact of preoperative humpback deformity on the functional outcome after surgery has been previously reported, the impact of humpback deformity, displacement, and the presence of bony cysts on union rate and time to healing after surgery has not been studied. Purpose The primary purpose of this study is to assess the association of humpback deformity, fragment displacement, and the size of cysts along the fracture line with the union rate and union time, following surgery of scaphoid nonunion. The second purpose of the study is to investigate the interobserver reliability in the evaluation of computed tomography (CT) scans of scaphoid nonunion. Patients and Methods From January 2008 to December 2018, 178 patients were surgically treated in our institution. After exclusion criteria were met, 63 patients with scaphoid delayed- or established nonunion, and preoperative CT scans of high quality (<2mm./ slice), were retrospectively analyzed. There was 58 men and 5 women with a mean age of 30 years (range: 16–72 years). Four orthopaedic surgeons and one radiologist independently analyzed the CT scans. The dorsal cortical angle (DCA), lateral intrascaphoid angle (LISA), the height-to-length ratio, the size of the cysts, and displacement of the fragments were measured. Healing was defined by CT scan, or by conventional X-ray, and status of no pain at clinical examination. Thirty-two of the patients had developed nonunion (>6 months postinjury), while 31 were in a stage of delayed union (3–6 months postinjury). Results Open surgery with cancellous or structural bone graft was the treatment of choice in 49 patients, 8 patients were treated with arthroscopic bone grafting, and 6 patients with delayed union were operated with percutaneous screw fixation, without bone graft. Overall union rate was 86% (54/63) and was achieved after 84 days (12 weeks) (mean). The failure rate and time to healing were not associated with the degree of the humpback deformity, size of the cysts, or displacement of the nonunion in general. However, greater dislocation, and the localization of the nonunion at the scaphoid waist, showed significant influence on the union rate. Dislocation at nonunion site, in the group of the patients who united after surgery, was 2.7 mm (95% confidence interval [CI]: 1.5–3.7), and in the group who did not unite was 4.2 mm (95% CI: 2.9–5.7); p = 0.048). Time from injury to surgery was significantly correlated with time to union (p < 0.05), but not associated with the union rate (p < 0.4). Patients treated arthroscopically achieved faster healing (42 days), (standard deviation [SD]: 22.27) as compared with patients treated by open techniques (92 days; SD: 70.86). Agreement among five observers calculated as intraclass correlation coefficient was for LISA: 0.92; for height-to-length ratio: 0.73; for DCA: 0.65; for size of cysts: 0.61; and for displacement in millimeters: 0.24, respectively. Conclusions The degree of humpback deformity and the size of cysts along the fracture line of scaphoid nonunion have no predictive value for the result, neither for the union rate nor the union time after surgery for the scaphoid nonunion. However, larger dislocation of the fragments measured at the scaphoid waist showed lower union rate. Time to healing following surgery is mainly influenced by the time from injury to the surgical treatment and may be influenced by the choice of the surgical technique. Interrater reliability calculation was best with LISA measurements, and worse with the measurements of the dislocation. Level of evidence This is a Level III, observational, case–control study.

Results of arthroscopic cancellous bone grafting for treatment of scaphoid nonunion in comparison with open cancellous bone grafting

“…All the patients from the AG group were followed prospectively by obtaining pre- and postoperative data, while data for the OG group were obtained retrospectively from a historic cohort (Gvozdenovic et al., 2021). Baseline data collected included gender, age, profession, side of injury, hand dominance, tobacco smoking and alcohol habits, comorbidity, dates of injury, details of surgery and union rates.…”

“…In addition, the morphological data on the scaphoid injury, such as the location of the fracture and humpback deformity measurements, were collected. Furthermore, displacement at the fracture site of >2 mm was included in the baseline data as a possible poor predictor for union rate at the scaphoid waist (Gvozdenovic et al., 2021).…”

Subchondral Radial and Ulnar K-Wire Positioning With Cancellous Bone Graft Shortens Union Time in Scaphoid Waist Nonunion

“…The presence of humpback deformity was defined as when lateral intrascaphoid angle was >45°and the heightto-length ratio was >0.65 on preoperative CT scans. 13,14 To evaluate the presence of avascular necrosis (AVN), we performed magnetic resonance imaging of the wrist if indicated on simple radiographs or CT scans. Suggestive AVN was confirmed intraoperatively by the presence of white sclerotic bone and absence of punctate bleeding after the tourniquet was released.…”

“…1A–C). The presence of humpback deformity was defined as when lateral intrascaphoid angle was >45° and the height-to-length ratio was >0.65 on preoperative CT scans 13,14 . To evaluate the presence of avascular necrosis (AVN), we performed magnetic resonance imaging of the wrist if indicated on simple radiographs or CT scans.…”

Extracorporeal shock wave treatment for post‑surgical fracture nonunion: Insight into its mechanism, efficacy, safety and prognostic factors (Review)

“…Prognostic factors of fracture union in PSFN. Certain studies have explored the predictive factors for fracture union in patients with PSFN receiving secondary surgery (57)(58)(59)(60)(61). These prognostic factors mainly focused on demographic characteristics (such as tobacco usage) and the recovery status of the fracture nonunion (including the dislocation distance, nonunion site and the occurrence of callus in the cortex) (57)(58)(59)(60)(61).…”