Reduction and Association of the Scaphoid and Lunate Versus Internal Brace for Scapholunate Ligament Reconstruction

Abstract

Background:

The purpose of this study is to compare outcomes in patients with isolated unrepairable scapholunate (SL) injuries treated with the reduction and association of the scaphoid and lunate (RASL) screw technique versus suture anchors with an internal brace (IB).

Methods:

Patients treated with either the RASL screw or IB technique for a complete, nonrepairable SL injury were identified. Radiographic and clinical data were recorded preoperatively, immediate postoperatively, and at final follow-up. Patients were then contacted via telephone survey, and Quick Disabilities of the Arm, Shoulder, and Hand (qDASH) questionnaire was administered. Patients with less than 6 months of follow-up were excluded.

Results:

Twenty-five patients (19 men, 6 women) with an average age of 43 (range = 23-66) years were identified (RASL = 14 and IB = 11). There were no differences between groups in radiographic parameters or range of motion at final follow-up, except for a smaller SL gap at final follow-up in RASL patients (1.5 vs 2.4 mm, P = .03). Four patients in the RASL (29%) group required additional procedures for screw removal secondary to screw breakage (n = 1) or screw migration/loosening (n = 3). One patient in the IB group had complete failure/diastasis postoperatively, and 36% (4/11) of patients had osteolysis at final follow-up. At final follow-up, qDASH was 26 versus 31 in the IB versus RASL groups (P = .79).

Conclusions:

Both RASL and IB have similar postoperative outcomes when treating SL injuries. It is important to note complications of screw breakage/loosening associated with RASL and recurrent diastasis/gapping and high rate of osteolysis with IB, although this has an unknown clinical significance.

Introduction

While the high prevalence and consequences of scapholunate (SL) instability are well known, management of these injuries remains controversial. Interventions are both numerous and lacking strong evidence regarding long-term function and mitigation of arthritic progression. Surgical options include arthroscopic debridement and pinning, capsular shrinkage, dorsal capsulodesis, reduction and association of the scaphoid and lunate (RASL) with a screw, the articulated scapholunate intercarpal screw, scapholunate axis method, bone ligament bone grafts, and a variety of tendon reconstructions.^{1 -7}

Novel suture constructs have also become more readily available and used recently, which have demonstrated good clinical outcomes in other orthopedic procedures. ⁸ Internal bracing (IB) is an augmentation method using high-strength nonabsorbable tape (Arthrex, Naples, Florida). The strength of suture augmentation constructs relative to the native SL ligament has been demonstrated via biomechanical studies, but there is a paucity of literature regarding clinical and patient-reported outcomes (PROs).^{9 -11} In addition, the differences in postoperative outcomes for RASL screw technique versus the Arthrex IB technique have not been evaluated.

More evidence comparing the long-term functional outcomes of various SL injury operative techniques is needed to optimize treatment and maximize return to function in this patient population. The primary purpose of this study was to compare postoperative outcomes (radiographic parameters, PROs, and clinical) in patients with isolated complete SL injuries treated with RASL with patients with SL injuries treated with IB. We hypothesized that in patients with isolated SL injuries, patients treated with IB would have similar postoperative outcomes compared with those treated with the RASL technique.

Methods

This was a retrospective chart review of demographic, clinical, and radiographic data with prospectively collected data for PROs at final follow-up, performed with institutional review board approval. We included patients ≥18 years of age who underwent operative treatment for an isolated SL injury by fellowship trained hand surgeons over a 5-year period at a single institution with a minimum clinical follow-up of 6 months. Of note, we did not evaluate any acute injuries amenable to primary repair.

Study Population

Patients were identified from an institutional surgical registry. All patients with diagnosis of isolated or associated SL injury between January 2018 and October 2023 were identified using the International Classification of Disease, Tenth Revision (ICD-10) codes S63.519A, S63.512A, and S63.511A. Of these patients, operatively treated patients were identified using the Current Procedural Terminology (CPT) code 25320.

Injury Classification

Patients were included if they had a complete SL injury based upon preoperative magnetic resonance imaging. Of those, 36% (n = 9) patients underwent arthroscopy prior to the procedure to confirm complete isolated SL injury. Mechanism of injury was divided into the following categories: fall on outstretched hand (FOOSH); sport, motor vehicle collision (MVC)/trauma; or other.

Surgical Treatment

Patients with isolated SL injury were further stratified by surgical treatment type. The first group consisted of patients treated with the RASL technique. In this technique, a dorsal approach to the wrist was used, and the SL interface was decorticated with a burr or a small curette was used to debride the center of SL articulation to promote the formation of a fibrous union. Two 0.45-mm Kirschner wires (K-wires) were used to assist with reduction of the SL interval. This was done by placing 1 K-wire in the proximal lunate and 1 in the distal scaphoid, joysticking the scaphoid out of flexion and the lunate out of extension, and clamping the 2 K-wires. The K-wires were strategically placed to be out of the zone of RASL screw trajectory. A separate incision, just volar to the first dorsal compartments, was made, and a radial styloidectomy was performed to get the proper trajectory of the screw, just proximal to the scaphoid ridge and into the ulnar corner aspect of the lunate. The K-wire was placed in this trajectory, and a headless compression screw with a smooth central shaft was inserted (Stryker Autofix, Kalamazoo, Michigan or Synthes Cannulated Compression Headless Screw System, Raynham, Massachusetts; Figure 1).

Figure 1.

Fluoroscopic images from reduction and association of the scaphoid and lunate technique.

The second group consisted of the Internal Brace system (Arthrex). A dorsal approach was used with a capsular sparing incision, followed by reduction of the scaphoid/lunate, as aforementioned with K-wires out of the zone of the suture anchor trajectory, and placement of the IB system dorsally. This system consists of a suture anchor-based construct (with or without tendon graft) that tethers the central portion of the lunate (single lunate anchor) to the proximal and distal poles of the scaphoid using 3.5-mm suture anchors. Of note, 73% of patients had tendon graft with extensor carpi radialis brevis (n = 5) or longus (n = 3). All patients had 1 or 2 K-wires placed in the scaphocapitate or SL interval (Figure 2). The RASL group was splinted with a thumb spica splint for 6 weeks, followed by progression with hand therapy. The IB group had a thumb spica splint, followed by K-wire removal at 6 weeks postoperatively, thermoplastic splinting for another 6 weeks, and progression with hand therapy.

Figure 2.

Fluoroscopic images from internal bracing technique.

Outcome Measures

Radiographic outcomes

Posteroanterior and lateral wrist radiographs were measured from each preoperative, immediate postoperative, and final follow-up visit to determine SL gap, SL angle, and dorsal scaphoid translation (DST). As not every patient received a clenched fist view, SL interval measurements were made separately on all available clenched fist views. Based on a prior study, osteolysis was defined as enlargement of tunnel size by >30% in the IB group as seen on follow-up radiographs. ¹²

Wrist range of motion

Available wrist range of motion (ROM) values were recorded for all patients on final follow-up by chart review. This included wrist extension, wrist flexion, radial/ulnar deviation, and pronosupination.

Postoperative complications/failure rates

From the date of surgery to the date of final follow-up, we recorded the rates of reoperation, K-wire breakage or migration, pin site infection, and re-diastasis of the SL interval.

Patient-reported outcomes

The Quick Disabilities of the Arm, Shoulder, and Hand (qDASH) Questionnaire was used to assess PROs following operative intervention for SL injury. ¹³ Lower normalized scores on the qDASH (range = 0-100) correlate to improved function. Additional survey questions included visual analog scale for pain (scale 0-10) and ability to perform open palm push-ups postoperatively if they were able to prior to their injury.

Statistical Analyses

All postoperative outcomes were quantified using descriptive statistics. Bivariate analyses (paired t test for continuous variables and χ² for categorical variables) were used to compare radiographic parameters. Postoperative complications/failure and PROs were compared between various surgical procedures. Alpha was set to .05.

Results

Study Population

We identified 58 patients with operatively managed SL injuries at our institution. Thirty-three patients did not have adequate radiographic data or follow-up and were excluded. Of the entire cohort of 25 patients, 13 patients (52%) provided PROs and completed the telephone survey.

Fourteen patients were treated with the RASL screw technique, and 11 patients were treated with IB. Table 1 summarizes patient age, sex, body mass index, hand dominance, laterality of injury, mechanism of injury, time to surgery, and mean follow-up. Most patients were men (19, 76%) and the average age was 43 (range = 23-66) years. The average follow-up from the date of surgery was 15.8 months. Mechanisms of injury included fall onto an outstretched hand (3, 12.0%), sport (7, 28.0%), trauma (12, 48.0%), and other (3, 12.0%).

Table 1.

Patient Demographics by Procedure.

Demographics	IB (n = 11)	RASL (n = 14)	P value
Age	43.2 (±12.8)	42.3 (±12.5)	.86
Gender
Female	3 (27%)	3 (21%)	.44
Male	8 (73%)	11 (79%)
Hand dominance
Left	0 (0%)	0 (0%)	.55
Right	11 (100%)	14 (100%)
Laterality injury
Left	2 (18%)	3 (21%)	.49
Right	9 (82%)	11 (79%)
MOI
FOOSH	2 (18%)	1 (7%)
Sport	2 (18%)	5 (36%)
Trauma (MVC)	6 (55%)	6 (43%)
Other	1 (9%)	2 (14%)
Time to surgery, wk	21 (5-87)	29 (6-88)	.51
Follow-up, mo	17.3 (±11.1)	14.6 (±10.4)	.09

Note. Mean (SD) (range) or n (%). IB = internal brace; RASL = reduction and association of the scaphoid and lunate; MOI = mechanism of injury; FOOSH = fall onto an outstretched hand; MVC = motor vehicle collision.

Radiographic outcomes

Across injury types and surgical techniques for isolated SL injuries (RASL = 14 and IB = 11), there were no differences in radiographic parameters on final follow-up (P > .05), except for a smaller final SL gap in RASL patients (P = .03; Table 2).

Table 2.

Radiographic Measurements and Range of Motion.

Preop	IB (n = 11)	RASL (n = 14)	P value
SL gap, mm	3.6 (±1.6)	3.0 (±1.8)	.39
SL angle, °	65.8 (±18.8)	81.2 (±12.8)	.03
Dorsal scaphoid translation, mm	1.6 (±1.5)	1.3 (±2.0)	.69
Immediate postop
SL gap, mm	1.4 (±0.9)	1.0 (±0.8)	.24
SL angle, °	51.7 (±11.6)	54.5 (±15.2)	.62
Dorsal scaphoid translation, mm	2.3 (±1.3)	1.1 (±1.7)	.06
Final follow-up
SL gap, mm	2.4 (±1.1)	1.5 (±1.0)	.03
SL angle, °	62.1 (±10.1)	62.4 (±13.9)	.96
Dorsal scaphoid translation, mm	2.2 (±1.5)	1.5 (±2.0)	.35
Range of motion, °
Final wrist flexion	56 (±16)	57 (±13)	.85
Final wrist extension	47 (±11)	49 (±14)	.71

Note. Mean (SD). IB = internal brace; RASL = reduction and association of the scaphoid and lunate; SL = scapholunate.

Range of motion

There were no significant differences in ROM on final follow-up across injury types (Table 2). Wrist flexion and extension were better in the RASL group (57° and 49°, respectively) compared with patients treated with IB (56° and 47°), although this difference was not statistically significant.

Patient-reported outcomes

QuickDASH scores were similar between those who underwent RASL versus IB (Table 3). Patient pain scores were slightly higher in IB patients than RASL patients, but this difference was not significant. Ability to perform push-ups did not vary significantly between the 2 groups.

Table 3.

Patient-Reported Outcomes Between RASL and IB Groups.

Outcome Measure	IB (n = 11)	RASL (n = 14)	P value
Patients who responded, no. (%)	3 (27%)	10 (71%)
Follow-up, y	1.6 (7 mo-3 y)	4.3 (9 mo-7 y)
qDASH (0-100)	26 (0-77)	31 (0-84)	.79
Final follow-up pain scores (0-10 VAS)	3 (0-10)	2 (0-7)	.62
Ability to perform open palm push-up, %	1 (33%)	4 (40%)	.84

Note. Mean (%) or (range). RASL = reduction and association of the scaphoid and lunate; IB = internal brace; qDASH = Quick Disabilities of the Arm, Shoulder, and Hand Questionnaire; VAS = visual analog scale.

Postoperative outcomes

The recorded complications included reoperation, hardware-related complications, infection, and osteolysis. Of 11 (36%) patients, 4 in the IB group had osteolysis around the anchors. One patient in the IB group had asymptomatic recurrence of SL diastasis postoperatively (Figure 3). There was one patient in the IB group who had a pin site infection treated with oral antibiotics. In the RASL group, 1 patient had a broken screw and 3 patients had loosening/migration of the screws, all of whom underwent removal of hardware (Figure 4).

Figure 3.

Fluoroscopic images demonstrating 1 month postoperative after internal brace (a), and at 3 months, with re-diastasis of the scapholunate interval (b).

Figure 4.

Fluoroscopic images of hardware complication with reduction and association of the scaphoid and lunate screw breakage (a), who underwent removal of hardware (b).

Discussion

A complete understanding of objective and PROs is essential for surgeons in choosing the best management strategy for patients with SL injuries. Across injury types and surgical techniques for isolated SL injuries (RASL = 14 and IB = 11), there were no differences in radiographic parameters or ROM on final follow-up (P > .05), except for a smaller final SL gap in RASL patients (P = .03). Complications included reoperation, hardware complications, pin site infection, and osteolysis. As stated by Lameire et al, ¹⁴ there is a need for studies comparing the outcomes of specific surgical treatments for SL instability to understand how to best guide management. This study contributes to this gap in the literature by reporting radiographic, clinical, and PROs of the RASL and IB approach.

The performance of the SL and RASL procedures is comparable when considering their radiographic outcomes. Radiographic outcomes play a critical role in evaluating the success of surgical interventions for SL injuries, as they provide objective markers of joint alignment and stability. Cadaveric and biomechanical studies have shown the benefit of these techniques for SL instability.^15,16 A cadaveric study of SL dissociation by Burnier et al ¹⁷ reported that RASL technique can effectively restore SL alignment, achieving improved and satisfactory radiographic parameters. Similarly, Kakar and Greene described the Scapholunate Ligament Internal Brace 360-Degree Tenodesis procedure, noting its potential in maintaining carpal alignment without the need for K-wire stabilization. ¹⁶

In this study, we reported on both RASL and IB techniques. We demonstrated comparable results in most radiographic parameters at final follow-up, including the SL angle and DST, with no statistically significant differences observed between the 2 groups. These findings suggest that both approaches effectively restore and maintain SL alignment in the short-term to mid-term postoperative period. This is supported by the available literature reporting on these techniques. ¹⁸ However, our study found a significant difference in the final SL gap, with the RASL group showing a smaller gap than the IB group (P = .03). Furthermore, the preoperative SL gap was significantly larger in the RASL group, which may signify more chronic injuries compared with the IB group (P = .03). This distinction highlights potential differences in the mechanical stability provided by these techniques, which may influence the long-term outcomes of SL ligament reconstructions. The use of a headless compression screw in the RASL procedure likely contributes to this outcome by allowing for direct and sustained compression across the SL interval. In contrast, the IB technique relies on a suture anchor construct, which, while effective, may lack the rigid fixation provided by a screw-based approach. The clinical significance of this radiographic difference warrants further investigation, as a smaller SL gap is often associated with improved joint congruency and potentially lower rates of degenerative changes in the long term.

In addition to the objective data of radiographic outcomes, it is of value to consider the more subjective outcomes as reported by patients. We used the qDASH upper extremity questionnaire to assess PROs following operative intervention for SL injury, as well as additional measures of pain, and ability to perform open palm push-ups. The current literature is lacking in data regarding PROs following operative interventions for SL injury. The qDASH is a reliable patient-reported measure of a variety of arm, shoulder, and hand disorders. ¹⁹ In this study, qDASH scores were similar between those who underwent RASL versus IB. Given the lack of data in the current literature, the intention of the study group is that the current cohort will continue to be followed and more patients recruited for more comprehensive 5-year and 10-year data in the future.

Complications remain an important consideration when evaluating the effectiveness and safety of surgical techniques for SL injuries. In this study, both the RASL and IB techniques were associated with complications, including hardware-related issues, infection, and osteolysis. Chen et al found that polyetheretherketone (PEEK) suture anchors may be associated with osteolysis, as 27% of 26 PEEK anchors demonstrated osteolysis at average follow-up of 12 months in patients undergoing hand and wrist surgery. ¹² This was similar to our finding of 36% of anchors demonstrating signs of osteolysis. Of note, there were no differences in rates of osteolysis when comparing IB with or without tendon graft. The clinical significance of osteolysis remains unknown although there is a theoretical increased risk for fracture or failure of the suture anchors, and future studies may help elucidate whether IB should be avoided in cases with smaller bone size. Previous studies have reported low complication rates with the IB technique, with both An et al (N = 17) and Wu et al (N = 14) reporting no major complications, described as reoperation or readmission. In fact, An et al (N = 17) only reported 2 patients with mild pain that subsided after 5 months.^20,21

The literature on RASL has shown a wider range of reported complication rates. Larson and Stern (N = 8) reported that 50% of cases managed with RASL required hardware removal for progressive lucency. ¹⁸ Similarly, Aibinder et al ²² (N = 12) reported 8 (67%) cases with screw lucency and 10 (83%) reoperations, where 8 required hardware removal for progressive osteolysis or pain and 2 required salvage procedures. These reoperations occurred at a mean of 9.2 months postoperatively (range = 1-24 months). In accordance with this, our study demonstrated a 29% (4/14) reoperation among the RASL group for removal of hardware. Although one may consider removal of hardware prior to such complications, we recommend leaving RASL screws in and only removing them as needed, as a second surgery could still be avoided in most patients. The complication profiles between the 2 techniques highlight critical considerations for surgical decision-making and patient counseling.

It is important to recognize the various limitations of this study. First, the patient population of this study is small, as many were excluded due to insufficient data and radiographs. Furthermore, due to patient participation, only 52% of the patients who were included for analysis have follow-up PRO data. Importantly, there was a discrepancy in the response rates, with 27% and 71% responding in the IB and RASL groups, respectively. In addition, only PRO scores at final follow-up were available as they were not collected preoperatively due to the retrospective nature of the study. Another limitation is the relatively short-term follow-up of our study. The average follow-up from the date of surgery was 15.8 months. It is our intention to continue following the outcomes of the included patients to capture long-term outcomes and potential late complications such as SLAC and SL instability in those with IB osteolysis, as well as to restudy results as the study population increases.

Conclusion

A variety of different SL surgical techniques have been described with varied success. Novel SL suture constructs are being increasingly used, with biomechanical studies showing adequate outcomes. However, there is a paucity in the literature regarding clinical outcomes and comparisons with other SL techniques such as the RASL. At our institution, RASL and IB have similar postoperative outcomes when treating SL injuries. It is important to note complications of screw breakage/loosening associated with the RASL technique and recurrent diastasis/gapping and high rate of osteolysis with the IB technique, although this has an unknown clinical significance.