Capitolunate Arthrodesis for Treatment of Scaphoid Nonunion Advanced Collapse (SNAC) Wrist Arthritis

Lunate-capitate arthrodesis for scaphoid nonunion: a comparative study

BACKGROUND

Scaphoid nonunion advanced collapse (SNAC) injuries are frequently associated with irreversible degenerative wrist arthritic changes that necessitate surgical intervention. Midcarpal fusion remains the mainstay of the management of SNAC II and III injuries. A successful four-corner fusion (4CF) relies on a stable lunate-capitate fusion (LCF). There have been reports of management relying solely on LCF. The outcomes of LC- and 4 C-fusions in SNAC injuries were not widely documented. The objective of this research is to provide valuable insights into the effectiveness of both fusion procedures in the management of SNAC II and III wrist injuries, with a focus on reporting associated complications, functional and radiological outcomes.

PATIENTS AND METHODS

This retrospective study encompassed 65 patients diagnosed with SNAC II and III wrist injuries who underwent limited wrist fusion procedures between 2015 and 2024, with a minimum of 2 years of postoperative follow-up. Exclusion criteria encompassed patients with carpal instability, prior wrist surgical interventions, and scapholunate advanced collapse. Following the fusion procedure performed, patients were stratified into two groups: the LCF group consisting of 31 patients, and the 4CF group comprising 34 patients. Preoperative and intraoperative data were retrieved from the patient's medical records. At their final follow-up appointments, patients underwent comprehensive radiographic and clinical evaluations. Clinical outcomes including hand grip strength, range of motion, the Disabilities of the Arm, Shoulder, and Hand Score, and the Mayo Modified Wrist Score, were compared between groups. Any associated complications were reported.

RESULTS

The average healing time was 74.7 ± 15.6 and 72.2 ± 13.2 days for the LCF and 4CF groups, respectively. At the final visit, all patients showed functional improvement relative to their preoperative status, with comparable wrist range of motions observed in both groups. The functional wrist scores were slightly better in the LCF patients (P > 0.05). The average grip strength was significantly greater in the LCF group (P = 0.04), with mean strength values of 86.8% and 82.1% of the contralateral side, for the LCF and 4CF groups, respectively.

CONCLUSION

The LCF is not less efficient than the 4CF in the treatment of SNAC II and III wrist injuries. Through a less time-consuming procedure, LCF can efficiently provide comparable results to 4CF.

LEVEL OF EVIDENCE

level IV evidence.

Clinical Outcomes of Lunocapitate Arthrodesis: A Retrograde Single-Screw Approach

BACKGROUND

A single-site retrospective study was designed to evaluate the clinical outcomes of single-screw lunocapitate arthrodesis (LCA) using a retrograde approach for the treatment of scapholunate advanced collapse (SLAC) wrist.

METHODS

We retrospectively identified 31 patients (33 cases) between September 2010 and December 2019 with SLAC wrist changes who were treated with single-screw LCA. Objective outcomes included time to fusion, union rate, range of motion, and grip and pinch strength recovery. Subjective outcomes included Disabilities of the Arm, Shoulder, and Hand (DASH) scores.

RESULTS

We report on 33 cases (7 female), mean age 58.4 years (range: 41-85), with SLAC wrist who underwent LCA. Our cohort reported a 94% union rate and a 90-day mean time to fusion. Final active wrist range of motion was 38° dorsiflexion, 35° volarflexion, 17° radial deviation, 17° ulnar deviation, 82° pronation, and 83° supination (mean: 450.8 days). Final grip and pinch strengths recovered was 75% gross grip, 84% lateral pinch, and 75% precision pinch (mean: 379.0 days) compared with the contralateral side. The mean postoperative DASH score was 27 (mean: 1203.9 days). Two nonunions were observed. Two hardware complications occurred: one symptomatic screw and one screw fatigue fracture.

CONCLUSIONS

We found retrograde single-screw LCA to be an effective salvage procedure for SLAC wrist. LCA is a less-taxing procedure, requires shorter operating time, and produces range of motion and grip and pinch strength recovery comparable to those of 4-corner arthrodesis. Furthermore, the viability of single-screw fixation may reduce hardware-related operative costs without compromising union rates.

Retrospective Comparison of Capitolunate Arthrodesis Using Headless Compression Screws Versus Nitinol Memory Staples for SLAC and SNAC Wrist: Radiographic, Functional, and Patient-Reported Outcomes

BACKGROUND

Nitinol memory compression staples have been proposed as an effective alternative to compression screws for capitolunate arthrodesis (CLA) for scaphoid nonunion advanced collapse (SNAC) and scapholunate advanced collapse (SLAC) wrist. The purpose of this study was to compare the clinical outcomes of CLA for SNAC or SLAC wrist treatment using either compression screws or nitinol staples.

METHODS

In all, 47 patients with CLA for SLAC or SNAC wrist with screws or nitinol staples were retrospectively identified. Primary outcome was fusion on radiographs and/or computed tomography. Secondary outcomes were hardware-related complications (HWCs) and other complications, range of motion, grip strength, and patient-reported outcome measures (PROMs), including Visual Analogue Pain scale; Disabilities of the Arm, Shoulder, and Hand score; and patient-rated wrist evaluation.

RESULTS

Of the 47 eligible patients, 40 (85%) were included: 31 patients in the staple group and 9 patients in the screw group. The average age was 49 (17-80) years. There was an 89% union rate for the screw group and a 97% union rate for the staple group. Two patients had screw backout: one who went onto union after screw removal and the other who went onto nonunion after hardware removal. There were 2 (6.5%) HWCs in the staple group. One patient had staple loosening requiring revision and the other dorsal impingement requiring staple removal after radiographic union. In all subsequent cases, the staples were countersunk with no impingement. No significant differences existed between any additional outcomes.

CONCLUSIONS

We found no differences between nitinol staples and screws for CLA regarding HWCs or PROMs. Nitinol staples may offer additional benefits as a safe and effective alternative to compression screws for wrist fusions.

Two-Corner Fusion or Four-Corner Fusion of the Wrist for Midcarpal Osteoarthritis? A Multicenter Prospective Comparative Cohort Study

BACKGROUND

Midcarpal osteoarthritis is a debilitating wrist pain, and a mainstay treatment is midcarpal fusion. The accepted standard for midcarpal fusion is four-corner fusion, but lately, two-corner fusion (i.e., capitolunate fusion) has gained popularity. This is the first prospective, multicenter, cohort study comparing capitolunate fusion with four-corner fusion for midcarpal osteoarthritis.

METHODS

Patients with scaphoid nonunion advanced collapse or scapholunate advanced collapse wrist of grade 2 to 3 undergoing capitolunate fusion or four-corner fusion between 2013 and 2019 were included. Sixty-three patients (34 with capitolunate fusion, 29 with four-corner fusion) were included. Patient demographics were similar between groups. Patient-Rated Wrist Hand Evaluation questionnaire score, visual analog scale pain score, grip strength, range of motion, and complications were measured at baseline and 3 months and 12 months postoperatively. Complications (i.e., nonunion, hardware migration, conversion to wrist arthrodesis, or arthroplasty) were determined.

RESULTS

A significant difference in Patient-Rated Wrist Hand Evaluation or visual analog scale pain score at 3 and 12 months postoperatively between the capitolunate fusion and four-corner fusion groups was not found. There were no differences in grip strength between patient groups preoperatively or 12 months postoperatively. At 12 months postoperatively, capitolunate fusion patients had better flexion compared with that in the four-corner fusion group (p = 0.002); there were no differences in complications and reoperation rates between groups.

CONCLUSIONS

Capitolunate fusion and four-corner fusion were comparable in terms of functional scores (i.e., Patient-Rated Wrist Hand Evaluation and visual analog scale pain scores) and complication scores. Capitolunate fusion showed favorable wrist mobility compared with four-corner fusion in treatment of midcarpal osteoarthritis. Capitolunate fusion advantages include use of less material, less need for bone-graft harvesting, and easier reduction of the lunate during fixation.

CLINICAL QUESTION/LEVEL OF EVIDENCE

Therapeutic, II.

Outcomes of Pediatric Scaphoid Nonunions Treated With Distal Radius Cancellous Autograft

BACKGROUND

The optimal management of pediatric scaphoid fracture nonunions is controversial. We hypothesize that pediatric patients with scaphoid fracture nonunions will have favorable functional outcomes with the utilization of nonvascularized distal radius cancellous autograft with open reduction and internal fixation (ORIF).

METHODS

A review was performed from 2012 to 2017 identifying skeletally immature patients with scaphoid fracture nonunions treated with ORIF and nonvascularized distal radius cancellous autograft, including demographic data, mechanism of injury, length of time from injury to treatment, operative procedure, length of immobilization, time to union, and complications.

RESULTS

Ten patients (9 males, 1 female) met inclusion criteria. Mean age was 14.3 SD 1.5 years. The majority of fractures were sustained during sports or secondary to a fall. Mean time between injury and orthopaedic evaluation was 33 weeks (SD 20 wk). Eight fractures occurred at the waist, and 2 occurred at the proximal pole. Four patients had a humpback deformity, and three presented with a dorsal intercalated segmental instability deformity. Nine patients were treated with a single cannulated compression screw with distal radius autograft. One patient also received a single Kirschner wire fixation in addition to a single cannulated screw and graft. Patients underwent a mean postoperative immobilization period of 14 SD 5 weeks. Two patients received a bone stimulator postoperatively. Radiographic union was documented after initial surgery in nine patients, with mean time to union of 17 SD 5 weeks. The 1 patient with persistent radiographic nonunion underwent revision fixation and repeat nonvascularized distal radius autograft, achieving union and resolution of symptoms. All patients ultimately reported full return to activity.

CONCLUSIONS

Pediatric scaphoid fracture nonunions that undergo ORIF using nonvascularized distal radius cancellous autograft have favorable rates of consolidation and functional outcomes. Surgeons should consider this source of grafting in operative management of scaphoid nonunions in children and adolescents.

LEVEL OF EVIDENCE

Level IV, therapeutic.

Outcomes of Arthroscopic Scaphoid Excision and Lunocapitate Fusion for Advanced Traumatic Arthritis of the Wrist

Background

Arthroscopic lunocapitate (LC) fusion can be an alternative surgical treatment for scapholunate advanced collapse (SLAC) or scaphoid nonunion advanced collapse (SNAC) of the wrist. We retrospectively reviewed patients who had arthroscopic LC fusion to estimate clinical and radiological outcomes.

Methods

From January 2013 to February 2017, all patients with SLAC (stage II or III) or SNAC (stage II or III) wrists, who underwent arthroscopic LC fusion with scaphoidectomy and were followed up for a minimum of 2 years, were enrolled in this retrospective study. Clinical outcomes included visual analog scale (VAS) pain, grip strength, active range of wrist motion, Mayo wrist score (MWS), and the Disabilities of Arm, Shoulder and Hand (DASH) score. Radiologic outcomes included bony union, carpal height ratio, joint space height ratio, and loosening of screws. We also performed group analysis between patients with 1 and 2 headless compression screws to fix the LC interval.

Results

Eleven patients were assessed for 32.6 ± 8.0 months. Union was achieved in 10 patients (union rate, 90.9%). There was improvmenet in mean VAS pain score (from 7.9 ± 1.0 to 1.6 ± 0.7, p = 0.003) and grip strength (from 67.5% ± 11.4% to 81.8% ± 8.0%, p = 0.003) postoperatively. The mean MWS and DASH score were 40.9 ± 13.8 and 38.3 ± 8.2, respectively, preoperatively and improved to 75.5 ± 8.2 and 11.3 ± 4.1, respectively, postoperatively (p < 0.001 for all). Radiolucent screw loosening occurred in 3 patients (27.3%), including 1 nonunion patient and 1 patient who underwent screw removal due to the screw migration encroaching the lunate fossa of radius. In group analysis, only the frequency of radiolucent loosening was higher in 1 screw (3 of 4) than 2 screw fixation (0 of 7) (p = 0.024).

Conclusions

Arthroscopic scaphoid excision and LC fusion for patients with advanced SLAC or SNAC of the wrist was effective and safe only in cases fixed with 2 headless compression screws. We recommend arthroscopic LC fusion using 2 screws rather than 1 to decrease radiolucent loosening, which might affect complications such as nonunion, delayed union, or screw migration.

Scaphoid excision with lunatocapitate fusion for the treatment of scaphoid nonunion with advanced collapsed wrist

PURPOSE

To investigate the union rate after lunatocapitate arthrodesis for the treatment of scaphoid nonunion advanced collapse (SNAC) wrists and to evaluate the clinical results of this technique.

METHODS

We conducted a prospective study between January 2014 and July 2017. Fifteen males with painful stage III SNAC wrists (average age, 32 years, range, 20-37 years; average follow-up time, 25.2 months, range, 20-36 months) underwent scaphoid excision and lunatocapitate fusion. Lunatocapitate fusions were fixed with headless Herbert screws with K-wire fixation (retrograde direction). Radiographs, wrist range of motion, and Mayo wrist score were examined.

RESULTS

All patients achieved radiographic and clinical union after lunatocapitate fusion during follow-up (average 10 months post-operatively). The flexion-extension arc was 70°, and the average Mayo wrist score was 74.3 points (eight with excellent, four with good, three with satisfactory, and one with poor result). Thirteen patients returned to work, whereas two with nonunion required surgical graft revision. Complete union was achieved at an average of 12 weeks after graft revision, with improved range of motion, and the patients returned to work with a change in their occupation.

CONCLUSIONS

Lunatocapitate arthrodesis is a satisfactory therapeutic alternative to four-corner fusion for SNAC wrists.

Capitolunate Arthrodesis: A Systematic Review

PURPOSE

To compile and review the indications, outcomes, and complications of capitolunate arthrodesis (CLA).

METHODS

We performed a literature search identifying 33 articles, 6 of which met inclusion criteria, including 80 patients. Included publications contained the results of CLA with minimum 12-month follow-up between 2000 and 2018. Data were pooled and analyzed focusing on the primary outcomes of union and complications.

RESULTS

Average age of patients was 48 years (range, 22-86 years), median follow-up was 34 months (range, 12-198 months), and most common indication was scaphoid nonunion advanced collapse (59%). Nearly half underwent a concomitant triquetrum excision (49%). Most patients were pain-free (78%) and returned to work (92%). Grip strength and visual analog pain scale both improved after CLA. Whereas 96% fused within a reported 42 to 210 days (median, 70 days), 11% of patients had complications including nonunion (3.8%) and loose hardware (6.3%). The reoperation rate was 14%, including wrist arthrodeses and wrist arthroplasty.

CONCLUSIONS

Capitolunate arthrodesis is a feasible option for scapholunate advanced collapse and scaphoid nonunion advanced collapse wrists with complications similar to those encountered in 4-corner arthrodesis.

TYPE OF STUDY/LEVEL OF EVIDENCE

Therapeutic IV.

Biomechanical Properties of Nitinol Staples: Effects of Troughing, Effective Leg Length, and 2-Staple Constructs

PURPOSE

Nitinol memory compression staples are a recent addition to carpal bone fixation. Compared with traditional staples, they have been shown to have superior compression at the far cortex relative to standard and traditional compression staples. The purpose of this study was to (1) determine the effective leg length of different nitinol staples, (2) confirm the effect of 1 versus 2 staples on biomechanical compression, and (3) determine the effect of troughing (countersinking the staple into bone) the bone on staple biomechanical properties.

METHODS

Three commonly used nitinol staples of various bridge and leg lengths were used in a bicortical sawbones block construct. There were 3 separate constructs tested, which included single staple, double staple, and troughed. We measured compression force, stiffness, and bending strength for each construct before and after cyclical 4-point bending. Compression mapping was used to determine the effective leg length of each staple, which included the distance that compression extended beyond the tips of the staple legs.

RESULTS

Effective leg length for each staple construct extended 2 mm distal to the tip of the shortest staple leg. Two staple constructs more than doubled compressive force and increased bending strength by greater than 90% in all staple types. There was no loss of compressive force before or after loading for single, double, or troughed constructs with any staple type.

CONCLUSIONS

This study supports that nitinol staples do not have to be placed bicortically to achieve adequate compression; placing staples 2 mm short of the far cortex has the same compression as bicortical placement; and troughing of the bone will not significantly diminish the biomechanical properties of the construct.

CLINICAL RELEVANCE

Better understanding of the effective leg length of nitinol staples provides support that bicortical placement is not necessary for adequate compression. This study supports troughing bone to minimize implant prominence.

Operative Management for Pediatric and Adolescent Scaphoid Nonunions: A Meta-analysis

INTRODUCTION

Scaphoid fractures in the pediatric population represent ∼3% of all hand and carpal fractures. Cast immobilization has been shown to yield excellent results in the acute phase, however some patients develop nonunions. Currently, there is no consensus regarding the best surgical treatment after development of a pediatric/adolescent scaphoid nonunion.

METHODS

A comprehensive literature review was performed utilizing Medline, Ovid, and Embase databases to compare surgical techniques for adolescent scaphoid nonunions on the basis of union rates, functional outcomes, and operative complications. Our initial search returned 2110 publications. Inclusion criteria consisted of a scaphoid fracture with >3 months of no clinical or radiographic improvement after cast immobilization and age less than 18 years. Ultimately, 11 studies met our criteria and were included in the final analysis.

RESULTS

A total of 176 surgically treated pediatric/adolescent scaphoid nonunions were identified from the 11 studies, including 157 nonvascularized bone graft procedures and 19 nongrafted rigid fixation procedures. Patients treated with a nongrafted method achieved union with a total random effects model revealing a union rate of 94.6%, whereas the grafted cohort had a union rate of 94.8%. Functional outcomes including range of motion and grip strength were significantly improved in both cohorts. Patients managed operatively with bone graft had 4 complications, in contrast those without bone grafting did not report complications (P=0.9).

CONCLUSION

Surgical treatment of pediatric/adolescent scaphoid fracture nonunions produce excellent union rates and functional outcomes after surgical intervention, using both grafted and nongrafted techniques. Future prospective studies are needed to assess if the outcomes of a specific technique are more favorable, as well as to determine if differences exist based on fracture location.

LEVEL OF EVIDENCE

Level III. This study is a meta-analysis of studies containing level of evidence of III or greater.

Midcarpal Arthrodesis Biomechanics: Memory Staples versus Cannulated Screws

BACKGROUND

Midcarpal arthrodesis is a treatment of choice in patients with midcarpal arthritis. Traditionally a four corner fusion has been favoured, however recent research has shown improved results when the triquetrum and scaphoid are excised. There is no clear evidence as to which remaining bones should be fused or which implants should be used. The purpose of this study is to compare the biomechanics of midcarpal arthrodesis after scaphoid and triquetrum excision, using memory staples or cannulated screws, in recognised construct patterns.

METHODS

36 identical sets of carpal bones were 3D printed from acetyl butyl styrene. Midcarpal arthrodeses were performed in three configurations with shape memory alloy staples or headless compression screws. This gave 6 treatment groups; lunocapitate single staple or screw, lunocapitate with 2 staples or screws, three corner fusion with 2 staples or screws. Peak torque to distraction was measured and analysed.

RESULTS

The peak torque to distraction was significantly greater in almost all constructs utilizing screws compared to staples, with two lunocapitate screws having the highest peak torque at both 1 and 3 mm distraction with 244 Nmm and 749 Nmm respectively (p < 0.05).

CONCLUSIONS

Constructs utilizing screws have a peak torque to distraction significantly higher when compared to staples. Our recommendation when performing a midcarpal arthrodesis after scaphoid and trapezium excision is to fuse the midcarpal joint with 2 headless compression screws.