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Structural Versus Nonstructural Bone Grafting for the Treatment of Unstable Scaphoid Waist Nonunion Without Avascular Necrosis: A Randomized Clinical Trial
We evaluated the impact of structural versus nonstructural bone grafting on the time to union, scaphoid deformity correction, and clinical outcomes in adults with unstable scaphoid waist nonunion without avascular necrosis. We hypothesized that nonstructural grafting would provide earlier time to union, restoration of scaphoid anatomy, and equivalent clinical outcomes compared with structural grafting.
Methods
We prospectively randomized 98 patients to undergo open reduction, iliac crest bone grafting with either corticocancellous (CC group) or cancellous bone only (C-only), and internal fixation using a Herbert screw. The lateral intrascaphoid angle (LISA) and scaphoid height length ratio (HLR) were measured on wrist computed tomography scans along the scaphoid longitudinal axis before surgery and an average of 84 weeks afterward. Pain, range of motion, grip strength, and Quick–Disabilities of the Arm, Shoulder, and Hand (QuickDASH) score were measured before surgery and an average 84 weeks afterward.
Results
The trajectory of scaphoid union showed a higher union rate of the C-only group at 12, 14, and 16 weeks after surgery. However, at 24 weeks after surgery, there was no difference between the groups, The union rate was 94% in patients treated with C-only and 90% with CC grafting. In patients with preoperative LISA less than 70° and/or HLR less than 0.80 (n = 53), there were no differences between the CC and C-only grafting techniques for radiographic and clinical outcomes, QuickDASH scores, and malunion rate. In patients who had preoperative LISA greater than 70° and/or HLR greater than 0.80 (n = 45), radiographic outcome measures, range of motion, and QuickDASH scores were significantly better in the CC than in the C-only group. Scaphoid malunion was observed in 9 of 22 of C-only patients (41%) and 4 of 23 of CC patients (18%).
Conclusions
The severity of the scaphoid deformity may be a factor in determining the best graft type, because this may affect the rate of successful deformity correction. Corticocancellous grafting in patients who had a high degree of scaphoid deformity provided consistent deformity correction and superior QuickDASH scores. Otherwise, C-only grafting provides earlier time to union and equivalent clinical and radiographic outcomes compared with CC grafting.
An unstable scaphoid nonunion alters wrist biomechanics and is often associated with concomitant dorsal intercalated segmental instability deformity that leads to progressive degenerative changes, known as scaphoid nonunion advanced collapse. Therefore, attempts to obtain union should pursued with internal fixation and bone grafting to restore the scaphoid height, length, and alignment.
reported that CC grafting is required to correct scaphoid deformity.
The purpose of this study was to evaluate the impact of CC compared with C-only bone grafting on the time to union and scaphoid deformity correction as measured using the lateral intrascaphoid angle
Measurement of the scaphoid humpback deformity using longitudinal computed tomography: intra- and interobserver variability using various measurement techniques.
Measurement of the scaphoid humpback deformity using longitudinal computed tomography: intra- and interobserver variability using various measurement techniques.
(HLR). We also compared clinical outcomes (pain, range of motion [ROM], and grip strength) and Quick–Disabilities of the Arm, Shoulder, and Hand (QuickDASH) score.
Development of an upper extremity outcome measure: the DASH (disabilities of the arm, shoulder and hand) [corrected]. The Upper Extremity Collaborative Group (UECG).
We hypothesized that C-only grafting would provide earlier time to union, restoration of the scaphoid anatomy, and equivalent clinical outcomes compared with the technique of CC grafting.
Materials and Method
We received approval from our institutional review board before beginning the study. Between July 2013 and December 2018, 142 consecutive patients with scaphoid fracture nonunion who were enrolled at the clinic at our university hospital were evaluated to participate in the study.
Inclusion criteria were patients aged 18 to 60 years with unstable scaphoid waist fractures that had not healed 6 months after the initial injury. Unstable scaphoid waist fracture was defined as a scapholunate (SL) angle greater than 60,°
Measurement of the scaphoid humpback deformity using longitudinal computed tomography: intra- and interobserver variability using various measurement techniques.
Exclusion criteria were transscaphoid perilunate or lunate dislocations, previous surgical treatment, stage 2 or higher scaphoid nonunion advanced collapse, and scaphoid nonunions with avascular necrosis. The diagnosis of nonunion was based on 4 radiographic views of the wrist (standard posteroanterior [PA], lateral, 45° pronation oblique, and PA with ulnar deviation), computed tomography (CT) scan of the wrist along the longitudinal axis of the scaphoid, and magnetic resonance imaging of the wrist to exclude avascular necrosis.
Thirty-four patients did not meet entry criteria and 6 refused to participate in the study (Fig. 1). The remaining 102 patients were given an information sheet; risks and benefits of operative treatment were discussed and written informed consent was obtained. They were randomized to undergo open reduction, iliac crest bone grafting with either CC or C-only, and internal fixation with a Herbert screw. Fifty-one patients were block-randomized using a computer-generated random number assignment to receive a CC graft (CC group), and 51 patients were randomized to receive a C-only graft (C-only group). One patient discontinued the intervention and 3 patients were lost to follow-up after 2 weeks. Finally, 98 patients, including 49 in the CC group and 49 in the C-only group, were analyzed (Fig. 1). Table 1 lists demographic data for both groups.
Figure 1Flowchart of the study showing the number of included, excluded, and actually analyzed patients in both groups.
Bisphosphonates for treatment of complex regional pain syndrome type 1: a systematic literature review and meta-analysis of randomized controlled trials versus placebo.
evaluated radiographic and clinical parameters. Average measurements taken by the 2 observers were recorded. After surgery, 2 other independent orthopedic surgeons who had level 3 experience
and who were blinded to the preoperative data evaluated radiographic and clinical outcomes. The average measurements of the 2 observers were recorded in both instances.
Before surgery and at an average of 84 weeks afterward, all patients were evaluated for clinical (pain, ROM, grip strength, and QuickDASH score) and radiographic parameters. The SL angle, RL angle, and CHR, based on Youm et al,
were evaluated using standard PA and lateral wrist radiographs. The LISA and HLR were evaluated on sagittal CT scans of the wrist along the longitudinal axis of the scaphoid (Fig. 2). Pain was assessed according to a self-reported visual analog scale (VAS) score.
The score was determined by measuring the distance (in millimeters) on a 10-cm line between the “no pain” mark and the patient's mark, providing a range of scores from 0 to 100, in which 0 indicated no pain and 100 indicated the worst possible pain. The total arcs of wrist motion (expressed as a percentage of the healthy side) were measured using a 2-arm goniometer.
Figure 2A The LISA is the angle between 2 perpendicular lines drawn from the distal (1) and proximal (2) articular joint surfaces, respectively. B The height to length ratio is measured using a baseline along the volar scaphoid, in which the length (L) is represented by 2 lines at right angles from the most proximal and distal points and height (H) is measured at right angles to the most dorsal point.
Surgery was performed under general anesthesia using an upper-arm tourniquet. The scaphoid was approached through a 4-cm longitudinal volar incision centered over the scaphoid tuberosity lateral to the flexor carpi radialis tendon. The sheath of the flexor carpi radialis was incised in line with the skin incision and the radioscaphocapitate ligament was incised longitudinally to expose the fracture. The scaphoid was inspected, and the fibrous tissue and sclerotic bone at the nonunion site were resected to the normal-appearing bone. The scaphoid was reduced, and its length was restored by introducing a lamina spreader into the gap. The dorsal intercalated segmental instability deformity was corrected and confirmed using the image intensifier.
In all patients, we used the radiograph of the normal scaphoid as a template for the nonunion defect and graft size. In patients in the CC group, the wedge dimensions were determined by measuring the gap using a 2-in flexible ruler. A tricortical CC graft was harvested from the ipsilateral iliac crest and prepared and placed into the gap. Then, the scaphoid was fixed and the fracture was compressed using a 3-mm Herbert bone screw (Zimmer), in a retrograde manner under image intensifier guidance. In the C-only group, after scaphoid reduction, the guide wire and a derotational Kirschner wire were inserted to maintain the reduction. A C-only bone graft was harvested from the ipsilateral iliac crest, prepared as chips, and packed into the gap. The scaphoid was then fixed without creating compression (to avoid shortening scaphoid length) using a 3-mm Herbert bone screw in a retrograde manner under the image intensifier guidance. The screw simply drew the scaphoid fragments closer together and acted like a threaded nail or a bridge plate. After the guide and derotational wires were removed, any residual gap was packed with graft.
Finally, the capsule and radioscaphocapitate ligament were repaired and the skin was sutured. The procedures were performed either by a senior author with level 4 experience
or by a surgeon who was under his direct supervision.
Postoperative follow-up
From baseline to 2 weeks after surgery, all patients were immobilized in a dorsal plaster thumb spica orthosis that extended above the elbow, and pain control medication was prescribed. Patients were advised to elevate the arms as much as possible throughout the day to reduce swelling. Active finger motion and shoulder exercises were allowed immediately after surgery and were performed several times a day. At week 2, skin sutures were removed and the above-elbow orthosis was replaced by a short-arm waterproof fiberglass cast thumb spica. At week 8, the cast was removed and a removable orthosis was applied until radiographic union was achieved. Patients commenced hand physical therapy sessions under the supervision of a specialized hand physiotherapist, with gentle hand and wrist exercises followed by more aggressive wrist exercises; heavy activities were allowed after scaphoid union.
Four radiographic views of the wrist (standard PA, lateral, 45° pronation oblique, and PA with ulnar deviation) were obtained at 2-week intervals until union. Scaphoid union was defined on the radiographs (in at least 3 of the 4 views)
Once union was suspected on plain radiographs, the patient underwent CT scans of the wrist along the longitudinal axis of the scaphoid to confirm union. If union was not confirmed, additional CT scans were obtained at 2-week intervals (Fig. 3). Union was considered to have been achieved when the CT demonstrated greater than 50% trabecular bridging across the nonunion site or graft interface.
Nonunion was defined when adverse features on the radiographs or less than 50% trabecular bridging on CT scan was identified at 24 weeks after surgery. Scaphoid malunion was defined as LISA of 45° or greater
Measurement of the scaphoid humpback deformity using longitudinal computed tomography: intra- and interobserver variability using various measurement techniques.
Measurement of the scaphoid humpback deformity using longitudinal computed tomography: intra- and interobserver variability using various measurement techniques.
on CT scan at the 84-week visit. Return to work depended on the nature of the patient's occupation. Gradual return to an office job was allowed within the confines of the cast, but manual work was allowed only after scaphoid union and within the limits of pain. Full return to work and recreational activities were allowed after union and pain relief. The time of full return to work and complications were recorded.
Figure 3Postoperative imaging follow-up chart to assess union.
A sample size estimate was performed on the time to union, LISA, HLR, and QuickDASH score, which were considered to be the primary outcome variables of the study.
The sample size required in each group to provide 90% power to detect a 10% difference with P < .05 was 49 patients for the time to union, 21 patients for LISA, 20 patients for HLR, and 23 patients for the QuickDASH score. Outcome measures were compared before surgery and at 84 weeks after surgery using an independent t test for continuous parametric variables and Mann–Whitney U test for continuous nonparametric variables. Categorical variables (sex, occupation, injured side, hand dominance, fracture classification, smoking, and complications) were compared using chi-square test. The rate of union, nonunion, and malunion were compared using Fisher exact test. P < .05 was considered statistically significant.
Results
The 2 groups were found to be similar for age, sex, hand dominance, side of injury, mechanism of injury, occupation, fracture classification,
time elapsed from initial injury to surgery, and smoking (Table 1). Both groups were also similar in terms of preoperative radiographic parameters (SL angle, RL angle, CHR, LISA, and HLR), clinical parameters (VAS, ROM, and grip strength), and QuickDASH score (Table 2).
Table 2Preoperative Radiographic and Clinical Parameters for Both Groups
The trajectory of scaphoid union showed a higher union rate for the C-only group at 12, 14, and 16 weeks after surgery; however, at 24 weeks there was no difference between groups (Fig. 4). Union was observed in 94% of patients treated with C-only (n = 46) and 90% with the CC grafting technique (n = 44). There were no differences between the C-only and CC groups for time to full return to work and complications (P > .05) (Table 3). We stratified patients into 2 subgroups according to the preoperative measurements of LISA and HLR. Group A had LISA less than 70° and/or HLR less than 0.80 (n = 53) and group B had LISA of 70° or greater and/or HLR of 0.80 or greater (n = 45). In group A, there were no differences in radiographic or clinical outcomes, QuickDASH score, or the rate of malunion in the CC technique compared with the C-only grafting technique (P > .05) (Table 4). In group B, there was significantly better improvement in radiographic outcomes, ROM, and QuickDASH scores in patients who underwent the CC technique compared with the C-only grafting technique (P < .05). In addition, the rate of malunion was 41% with the C-only technique compared with 18% with the CC technique (P < .05). However, we found no differences between the techniques for the VAS score and grip strength (P > .05) (Table 5).
Figure 4Chart graph comparing trajectory of union rate of both groups represented in 2-week intervals. ∗P value is statistically significant.
Complication rates for the fixation procedure were 10% and 12% (P > .05), whereas those for the graft donor site were 16% and 15% (P > .05) in the C-only and CC groups, respectively. Superficial wound infections were treated with oral antibiotics and wound care. Complex regional pain syndrome was treated with physiotherapy, nonsteroidal anti-inflammatory drugs, and bisphosphonates.
Bisphosphonates for treatment of complex regional pain syndrome type 1: a systematic literature review and meta-analysis of randomized controlled trials versus placebo.
Three patients had an injury to the palmar cutaneous branch of the median nerve, which caused a painful neuroma treated by neuroma excision. Nonunion was observed in 5 patients in the CC group and 3 in the C-only group. No apparent technical errors were reported in cases of nonunion, except an eccentric screw placement in one patient in the C-only group and graft displacement in 2 patients in the CC group. One patient in the C-only and 2 in the CC group were tobacco smokers (20 cigarettes/d). The nonunion patients were treated using revision surgeries (open reduction and cancellous iliac bone graft with Kirschner wire fixation). All of these patients were completely united at an average of 16.5 weeks (range, 12–19 weeks) after the revision surgery.
Discussion
The study demonstrated earlier scaphoid union in patients treated with the C-only grafting technique. Cancellous bone–only grafting simplifies operative procedures because reshaping of the CC graft is not required. Although there was no significant difference between groups regarding union rate at the end of the study, the trajectory of healing (Fig. 4) showed an accelerated union rate with the C-only versus CC grafting technique. Cancellous iliac bone graft has a higher concentration of osteoblasts and osteocytes, which suggests superior osteogenic properties compared with the CC graft.
However, the CC bone graft has a higher trabecular density, which may lend better mechanical support and structural integrity. This density comes at the cost of a comparatively limited supply of osteoblasts, osteocytes, and other cellular progenitors.
We preferred to use iliac crest bone grafting rather than distal radius because we think that the distal radius has a lower bone volume, more slender trabecular architecture, and lower bone turnover than the iliac crest, and the osteoblasts in the distal radius have a lower range of functional activity.
Local distal radius bone graft versus iliac crest bone graft for scaphoid nonunion: a comparative study [published correction appears in Musculoskelet Surg. 2013 Aug;97(2):115. Garg, Bhavuk [removed]; Kotwal, Prakash P [removed]].
studied the biomechanical properties of compression screws and concluded that the Herbert screw can resist bending forces, but it is unable to withstand cyclical multiaxis loading or rotation. Therefore, we prefer to continue to use a removable wrist orthosis until union. However, there was no significant difference between groups regarding return to work (P > .05). We think that the time taken for return to work depends on many factors including the nature of the patient's occupation and the attitudes of the patient, employer, and insurer, which makes it questionable outcome measure in any event.
There is controversy regarding union rate between studies that used C-only
A comparison of the rates of union after cancellous iliac crest bone graft and Kirschner-wire fixation in the treatment of stable and unstable scaphoid nonunion.
grafting to treat scaphoid nonunions. Our study reported similar rates of union of 94% (n = 46) in patients in the C-only group and 90% (n = 44) for the CC group. Compared with reports in the literature, these discrepancies might be related to differences in the fixation method (Kirschner wires or Herbert screws), graft site choice (distal radius or iliac crest), and/or sampling size errors.
To evaluate the impact of graft choice (structural vs nonstructural) on scaphoid deformity correction, we classified the scaphoid deformity according to the degree of preoperative LISA into 2 categories composed of a lesser degree of deformity and a high degree of deformity. The lesser degree of deformity was defined as a preoperative LISA of less than 70° and the high degree of deformity was LISA greater than 70°. There were no differences between the CC and C-only grafting techniques with respect to the correction of deformity and rate of malunion in patients who had the lesser degree of scaphoid deformity. This might be related to impaction of the cancellous chips into the nonunion gap, avoidance of compression at the fracture site, and/or the nature of the graft site choice (cancellous iliac crest graft). However, in patients who had a high degree of scaphoid deformity, the rate of malunion was significantly higher and associated with lower QuickDASH scores with the C-only grafting technique. Sayegh and Strauch
systematically reviewed 23 retrospective studies composed of 604 patients with unstable scaphoid waist fracture nonunions, who were treated with iliac or distal radius CC or C-only grafts fixed using a screw or Kirschner wires. They concluded that the C-only graft provided the shortest interval to union and poorer deformity correction, but the CC patients were associated with consistent deformity correction and superior Mayo wrist scores. Kim et al
retrospectively compared C-only and CC grafts for the treatment of 35 scaphoid nonunions with preoperative LISA less than 70° and HLR less than 0.80. They stated that C-only grafting led to earlier bone union than CC grafting; the 2 procedures were similar in wrist function and deformity correction. Moreover, Cohen et al
treated 12 scaphoid nonunions with a mean preoperative LISA of 49° using headless compression screw fixation and C-only grafting, and they stated that all patients had noteworthy postoperative deformity correction as measured by the LISA. Based on our results, we suggest that the severity of the scaphoid deformity may be considered a prognostic factor in determining the type of grafting, success rate of deformity correction, and subsequent outcomes. Therefore, we think that using CC grafting in patients who have a high degree of scaphoid deformity (LISA >70° and/or HLR >0.80) provides consistent deformity correction and a superior QuickDASH score; otherwise C-only grafting is more appropriate because it provides an earlier time to union and equivalent clinical and radiographic outcomes compared with the CC grafting technique.
Measurement of the scaphoid humpback deformity using longitudinal computed tomography: intra- and interobserver variability using various measurement techniques.
Development of an upper extremity outcome measure: the DASH (disabilities of the arm, shoulder and hand) [corrected]. The Upper Extremity Collaborative Group (UECG).
Bisphosphonates for treatment of complex regional pain syndrome type 1: a systematic literature review and meta-analysis of randomized controlled trials versus placebo.
Local distal radius bone graft versus iliac crest bone graft for scaphoid nonunion: a comparative study [published correction appears in Musculoskelet Surg. 2013 Aug;97(2):115. Garg, Bhavuk [removed]; Kotwal, Prakash P [removed]].
A comparison of the rates of union after cancellous iliac crest bone graft and Kirschner-wire fixation in the treatment of stable and unstable scaphoid nonunion.
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