Scaphoid blood flow and acute fracture healing

Perfusion of the proximal scaphoid pole: correlation between preoperative ge-MRI and intraoperative findings

BACKGROUND

Gadolinium enhanced MRI (ge-MRI) is considered as gold standard for perfusion evaluation in case of scaphoid nonunion (SNU). However, its clinical value and specificity is still not clearly evaluated. This study compares preoperative ge-MRI-based perfusion assessment and intraoperative proximal pole (PP) perfusion after scaphoid reconstruction by vascularized bone grafts. In addition, the postoperative osseous consolidation (OC) was correlated to intraoperative perfusion findings.

METHODS

Between 08/2010 and 01/2020, 60 of 271 patients with scaphoid nonunion received a vascularized radius bone graft for reconstruction. Medical reports were checked for intra-op perfusion findings. Consolidation rate was assessed at mean follow-up of 3 months by CT evaluation. In 50 cases (83.2%), complete medical and radiological history could be obtained. Preoperative ge-MRI was reevaluated by a blinded radiologist for advanced analysis of sensitivity and specificity.

RESULTS

Preoperative ge-MRI (initial finding, IF) showed 23 avascular, 20 malperfused, and seven vital PP. Blinded radiological follow-up (second finding, SF) revealed 14 avascular, 28 malperfused, and 8 vital PP, with a concordance of 65.3% (n = 35). After correlation with the intra-op findings, a specificity of preoperative ge-MRI of 76.5% (IF) and 88.2 (SF), respectively, was revealed for exclusion of avitality. For detection of malperfusion, there was a sensitivity of 92.7% (IF) and 85.4% (SF), respectively. Complete OC was seen 12 weeks postoperatively in 37 (73.5%), partial OC in 9 (18.3%), and nonunion in 4 cases (8.2%) on CT-scans. Of the 41 malperfused/avascular PP, 31 (75.6%) progressed to complete and 6 (14.6%) to partial (at least 2 adjacent CT-layers of 2 mm) OC, with 4 nonunions.

CONCLUSION

The sensitivity and specificity of ge-MRI for detection/ exclusion of malperfusion/avitality of the PP was lower than expected. Therewith, the intraoperative assessment of PP perfusion regains a high value in decision-making for the appropriate graft. We recommend preservation of the dorsal radial vascular plexus initially until the vascularity of the proximal pole has been estimated. Patient education for all contingencies and retraction options should be obtained.

A meta-analysis of union rate after proximal scaphoid fractures: terminology matters

Heterogeneity in the anatomical definition of 'proximal' affects the comparison of outcomes of these scaphoid fractures. This study aims to review published outcomes of all variants to determine both, differences in terminology, and union rate based upon definition. A literature search was conducted to identify articles that reported descriptions and union rate of all acute (<8 weeks of injury) proximal scaphoid fractures in adult patients (>16 years old). Proximal fractures were grouped as reported ('third', 'pole', 'fifth' or 'undefined'). The data were pooled using a fixed-effects method, and a meta-analysis was conducted to compare relative risk (RR) of non-union against non-proximal fractures. Qualitative analysis of 12 articles included three main definitions: 'proximal' (1 article), 'proximal third' (3 articles), and 'proximal pole' (8 articles). Only 6 articles adopted a specific anatomical or ratio description. In a pooled meta-analysis of union rates (15 articles), 'proximal third' and 'proximal pole' fractures demonstrated a relative risk (RR) of non-union of 2.3 and 3.4 in comparison to non-proximal fractures, respectively. Operative management yielded lower non-union rates than non-operative for all fracture types (6% vs. 18%). In conclusion, non-union risk varies depending on definition, with non-standardised classifications adding heterogeneity to reported outcomes. We recommend an approach utilizing fixed anatomical landmarks on plain radiographs (referencing scaphoid length and scapho-capitate joint) to standardise reporting of proximal fracture union in future studies. Abbreviations: CI: confidence intervals; CT: computer tomography; Df: degrees of freedom; DL: dersimonian and laird estimator; MRI: magnetic resonance imaging; NICE: national institute for health and care excellence; OTA: orthopaedic trauma association; PA: posterior-anterior; PRISMA: preferred reporting items for systematic reviews and meta analyses; RCT: randomised controlled trial; RR: relative risk; SNAC: scaphoid non-union advanced collapse; UK: United Kingdom.

Posttraumatic Avascular Necrosis After Proximal Femur, Proximal Humerus, Talar Neck, and Scaphoid Fractures

Posttraumatic avascular necrosis (AVN) is osteonecrosis from vascular disruption, commonly encountered after fractures of the femoral neck, proximal humerus, talar neck, and scaphoid. These locations have a tenuous vascular supply; the diagnosis, risk factors, natural history, and treatment are reviewed. Fracture nonunion only correlates with AVN in the scaphoid. In the femoral head, the risk is increased for displaced fractures, but the time to surgery and open versus closed treatment do not seem to influence the risk. Patients with collapse are frequently symptomatic, and total hip arthroplasty is the most reliable treatment. In the humeral head, certain fracture patterns correlate with avascularity at the time of injury, but most do not go on to develop AVN due to head revascularization. Additionally, newer surgical approaches and improved construct stability appear to lessen the risk of AVN. The likelihood of AVN of the talar body rises with increased severity of talar injury. The development of AVN corresponds with a worse prognosis and increases the likelihood of secondary procedures. In proximal pole scaphoid fractures, delays in diagnosis and treatment elevate the risk of AVN, which is often seen in cases of nonunion. The need for vascularized versus nonvascularized bone grafting when repairing scaphoid nonunions with AVN remains unclear.

Success of scaphoid nonunion surgery is independent of proximal pole vascularity

We followed 35 consecutive patients with scaphoid nonunions in a prospective longitudinal registry. All nonunions were treated with curettage, non-vascularized autogenous grafting and headless screw fixation. Preoperative magnetic resonance imaging, intraoperative bleeding points and histopathological analysis of cancellous bone in the proximal pole were recorded as measures of viability. Healing was categorized as ≥50% bony bridging on computed tomographic images in the plane of the scaphoid. Nine of 23 proximal poles demonstrated ischaemia on magnetic resonance imaging but none were interpreted as infarcted. Twenty-eight of 33 were found to have impaired vascularity as assessed by intraoperative bleeding. Fourteen of 32 demonstrated ≥50% trabecular necrosis and four of 33 demonstrated ≥50% tissue necrosis on histopathological analysis. Thirty of 33 demonstrated focal or robust remodelling activity. Despite pathological evidence of impaired vascularity in over half of the patients, 33 of the 35 scaphoids had healed by 12 weeks. We conclude that proximal pole infarction is decidedly rare and that vascularized bone grafting is seldom required.

LEVEL OF EVIDENCE

IV.

Fixation of proximal pole scaphoid nonunion with non-vascularized cancellous autograft

We present 20 patients with established proximal pole scaphoid nonunions treated with curettage and cancellous autograft from the distal radius and screw fixation. Fractures with significant proximal pole fragmentation were excluded. Patients were treated at a mean of 26 weeks after injury (range 12-72). Union occurred in 18 of 20 patients (90%) based on computed tomographic imaging. The two nonunions that did not heal were treated with repeat curettage and debridement and iliac crest bone grafting without revision of fixation. Union was achieved in both at a mean of 11 weeks after the revision procedures. Our findings suggest that non-vascularized cancellous autograft and antegrade fixation is a useful option for the treatment of proximal pole scaphoid nonunions.

LEVEL OF EVIDENCE

IV.

Changes in Scaphoid Bone Density after Acute Fracture

The radiographic density of the proximal fragments of 16 scaphoid fractures was assessed on scaphoid series radiographs taken at 6 to 12 weeks. In addition, dual energy X-ray absorptiometry measurements of bone mineral density in the distal radius and proximal and distal fracture fragments were performed at 1 to 2 weeks and 6 to 12 weeks. Median reductions of 9% and 10% were observed in bone mineral density in the proximal fracture fragment and the distal radius respectively, but these did not correlate with the radiographic density of the proximal fragment. A greater median reduction in bone mineral density (27%) was observed in the distal fracture fragment and more bone loss occurred at this site when there was an apparent increase in the radiographic density of the proximal fragment (median fall of 0.23 g/cm2 versus 0.14 g/cm2). Thus, apparent increased radiographic density of the proximal fragment may be due to increased bone loss from the distal fragment.

Dorsal vascularized grafting for scaphoid nonunion: a comparison of two surgical techniques

OBJECTIVES

To compare the radiographic and functional outcomes of 2 surgical techniques for treating scaphoid nonunion.

DESIGN

Randomized prospective study.

PATIENTS/PARTICIPANTS

Researchers assessed the outcomes every 2 weeks until bone healing and at discharge.

INTERVENTIONS

(1) Vascularized bone grafting (VBG) using the 1, 2 intercompartmental suprareticular artery and (2) a distal radius nonvascularized bone graft.

MAIN OUTCOMES/INTERVENTIONS

Time to union (primary), union rate, and functional outcomes.

RESULTS

Seventy-five patients were followed for 29 months; 2 were lost to final follow-up. Both groups had similar baseline characteristics. The VBG group reached bone union earlier by 12 days (P = 0.002), but union rates were similar (P = 0.312). There was also less ulnar deviation in the VBG group (P = 0.03). There were no other differences between either intervention groups.

CONCLUSIONS

Although the VBG group attained earlier union, this may not be clinically meaningful, nor justify the greater technical difficulty and use of resources associated with this intervention.

LEVEL OF EVIDENCE

Therapeutic Level II. See instructions for authors for a complete description of levels of evidence.