Accuracy of enhanced and unenhanced MRI in diagnosing scaphoid proximal pole avascular necrosis and predicting surgical outcome

Scaphoid Nonunions: Local Vascularized Bone Flaps

If untreated, scaphoid nonunions may progress to scaphoid nonunion advanced collapse in a substantial portion of cases and may require salvage procedures. Multiple different techniques have been described to address scaphoid nonunion. Vascularized bone flaps (VBFs) are associated with faster time to union compared with nonvascularized grafts. Because these are local pedicled flaps, they do not require microsurgical anastomoses and should be within the armamentarium of all hand surgeons. Appropriately chosen local VBFs, can achieve union rates up to 90% to 100% in appropriately selected patients.

Society of skeletal radiology position paper - recommendations for contrast use in musculoskeletal MRI: when is non-contrast imaging enough?

The following White Paper will discuss the appropriateness of gadolinium administration in MRI for musculoskeletal indications. Musculoskeletal radiologists should consider the potential risks involved and practice the judicious use of intravenous contrast, restricting administration to cases where there is demonstrable added value. Specific nuances of when contrast is or is not recommended are discussed in detail and listed in table format. Briefly, contrast is recommended for bone and soft tissue lesions. For infection, contrast is reserved for chronic or complex cases. In rheumatology, contrast is recommended for early detection but not for advanced arthritis. Contrast is not recommended for sports injuries, routine MRI neurography, implants/hardware, or spine imaging, but is helpful in complex and post-operative cases.

Utility of preoperative MRI for assessing proximal fragment vascularity in scaphoid nonunion

Aims

The benefit of MRI in the preoperative assessment of scaphoid proximal fragment vascularity remains controversial. The purpose of this study is to compare preoperative MRI findings to intraoperative bleeding of the proximal scaphoid.

Methods

A retrospective review of 102 patients who underwent surgery for scaphoid nonunion between January 2000 and December 2020 at a single institution were identified. Inclusion criteria were: isolated scaphoid nonunion; preoperative MRI assessing the proximal fragment vascularity; and operative details of the vascularity of the proximal fragment with the tourniquet deflated. MRI results and intraoperative findings were dichotomized as either 'yes' or 'no' for the presence of vascularity. A four-fold contingency table was used to analyze the utility of preoperative MRI with 95% confidence intervals. Relative risk was calculated for subgroups to analyze the association between variables and MRI accuracy.

Results

Preoperative MRI identified 55 proximal scaphoid fragments with ischaemia and 47 with vascularized proximal fragments. After the proximal fragment was prepared, the tourniquet was deflated and assessed for bleeding; 63 proximal fragments had no bleeding and 39 demonstrated bleeding. MRI was not reliable or accurate in the assessment of proximal fragment vascularity when compared with intraoperative assessment of bleeding. No patient or MRI factors were identified to have a statistical impact on MRI accuracy.

Conclusion

Current preoperative MRI protocols and diagnostic criteria do not provide a high degree of correlation with observed intraoperative assessment of proximal fragment bleeding. While preoperative MRI may assist in surgical planning, intraoperative assessment remains the best means for assessing proximal fragment vascularity in scaphoid nonunion. Future efforts should focus on the development of objective measures of osseous blood flow that may be performed intraoperatively.

Outcomes after arthroscopic treatment for scaphoid nonunion using ipsilateral radius bone graft and a headless compression screw: a comparison between the patients with and without avascular necrosis

PURPOSE

To determine whether avascular necrosis can affect clinical outcomes or the union incidence after arthroscopic bone grafting for the treatment of scaphoid nonunion.

METHODS

This retrospective comparative study included thirty-four patients with scaphoid nonunion that underwent arthroscopic bone graft from the ipsilateral radius and internal fixation. The patients were divided into two cohorts (group A, with avascular necrosis, n = 15; group B, without avascular necrosis, n = 19) based on pre-operative magnetic resonance imaging findings. Additionally, the patients were grouped in accordance with the location of nonunion (waist, n = 27; proximal pole, n = 7). The mean follow-up was 20.7 months (range 12.0-40.0 months). Clinical outcomes, including the visual analog scale (VAS) pain score, grip strength, range of motion (ROM), Mayo Wrist Score (MWS), and Disabilities of the Arm, Shoulder, and Hand (DASH) score, were evaluated. Radiographic measurements for carpal bone alignment were assessed as well.

RESULTS

Union rates did not differ between groups (group A, 93.3%; group B, 94.7%: p = 0.863), and the post-operative VAS pain score, ROM, and MWS were similar at follow-up for a minimum of one year. DASH and grip strength were significantly better in group B, but the intergroup differences were minimal (mean DASH 11.9 versus 9.6; mean grip strength 77.5% versus 95.4% of contralateral side). There was no significant intergroup difference in mean time to achieving union (group A, 14.9 weeks; group B, 14.6 weeks; p = 0.900). In post-operative radiographic assessments, no significant intergroup differences were noted in any of the parameters. Subgroup analysis regarding the location of nonunion showed there were no significant intergroup differences in union rates, mean time to achieving union, and clinical outcome measures at the last post-operative follow-up.

CONCLUSIONS

Arthroscopic bone grafting and internal fixation in the treatment of scaphoid nonunion provided good union rates and satisfactory outcomes regardless of vascularity status.

Vascularised versus non-vascularised bone graft for scaphoid nonunion: Meta-analysis of randomised controlled trials and comparative studies

Background

Numerous studies have investigated surgical techniques for vascularised bone graft (VBG) for scaphoid nonunion; however, their efficacies remain unclear. Thus, to estimate the union rate of VBG for scaphoid nonunion, we performed a meta-analysis of randomised controlled trials (RCTs) and comparative studies.

Methods

A systematic search was conducted using PubMed, Scopus, Web of Science, and Cochrane Central Register of Controlled Trials. The search formula was as follows: ((scaphoid nonunion) OR (scaphoid pseudarthrosis)) AND (bone graft). Only RCTs were used in the primary analysis, and comparative studies, including RCTs, in the secondary analysis. The primary outcome was nonunion rate. We compared the outcome between VBG and non-vascularised bone graft (NVBG), pedicled VBG and NVBG, and free VBG and NVBG.

Results

This study included a total of 4 RCTs (263 patients) and 12 observational studies (1411 patients). In the meta-analyses of both RCTs only and RCTs and other comparative studies, no significant difference in nonunion rate was found between VBG and NVBG (summary odds ratio [OR], 0.54; 95% confidence interval [CI], 0.19-1.52 and summary OR, 0.71; 95% CI, 0.45-1.12), respectively. The nonunion rates of pedicled VBG, free VBG, and NVBG were 15.0%, 10.2%, and 17.8%, respectively, and no significant difference was found.

Conclusions

Our results indicated that the postoperative union rate in NVBG is similar to that in VBG; thus, NVBG could be the first choice of treatment for scaphoid nonunion.

Osseous Pathology on Wrist Magnetic Resonance Imaging

Advanced imaging of the osseous structures of the wrist by magnetic resonance imaging (MRI) yields powerful information regarding marrow composition and overall bone structure. Various forms of pathology, both benign and malignant, have unique marrow signal abnormalities that can be easily detected by MRI given its high sensitivity to radiographically occult processes. In particular, osseous pathology can be seen in the setting of traumatic, degenerative, congenital, infectious, and neoplastic conditions. The acuity or chronicity of these conditions can often be determined by imaging to aid in appropriate therapy. A thorough understanding of the breadth of pathology and corresponding MRI appearances can allow the interpreting radiologist to formulate a concise and accurate assessment of an examination.

Mid-term outcome of volar plate fixation for scaphoid nonunion

AIMS

Fixation of scaphoid nonunion with a volar locking plate and cancellous bone grafting has been shown to be a successful technique in small series. Few mid- or long-term follow-up studies have been reported. The aim of this study was to report the mid-term radiological and functional outcome of plate fixation for scaphoid nonunion.

METHODS

Patients with a scaphoid nonunion were prospectively enrolled and treated with open reduction using a volar approach, debridement of the nonunion, and fixation using a locking plate and cancellous bone grafting, from the ipsilateral iliac crest. Follow-up included examination, functional assessment using the patient-rated wrist/hand evaluation (PRWHE), and multiplanar reformation CT scans at three-month intervals until union was confirmed.

RESULTS

A total of 49 patients with a mean age of 31 years (16 to 74) and a mean duration of nonunion of 3.6 years (0.4 to 16) were included. Postoperatively, the nonunion healed in 47 patients (96%) as shown on CT scans. The mean time to union was 4.2 months (3 to 12). Due to impingement of the plate on the volar rim of the radius and functional limitation, the hardware was removed in 18 patients. At a median follow-up of 38 months in 34 patients, the mean active range of motion (ROM) improved significantly from 89° to 124° (SD 44°; p = 0.003). The mean grip strength improved significantly from 52% to 79% (SD 28%; p < 0.001) of the contralateral side. The mean PRWHE score improved significantly from 66 to 17 points (SD 25; p < 0.001).

CONCLUSION

Locking plate fixation supplemented with autologous cancellous bone grafting is a successful form of treatment for scaphoid nonunion. Functional outcomes improve with the passage of time, and mid-term results are excellent with a significant improvement in ROM, grip strength, and functional outcome as measured by the PRWHE. Cite this article: Bone Joint J 2020;102-B(12):1697-1702.

Imaging of the Hand and Wrist

Imaging plays a key role in the evaluation and treatment planning of hand and wrist injuries in athletes. Depending on the suspected injury, a combination of conventional radiographs, computed tomography, magnetic resonance imaging, magnetic resonance arthrography, and/or ultrasound may be indicated. This article reviews the strengths and limitations of these imaging modalities and how they can be utilized in commonly encountered clinical questions.

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.

Radiographic/MR Imaging Correlation of the Wrist

In this review article, the authors discuss the imaging features of the most common pathologic conditions of the wrist by putting the emphasis on radiographic and MR imaging correlations. A topographic approach based on the 3 functional columns of the wrist (radial, central, and ulnar) serves as a framework. The pathologic conditions are classified, based on the structures involved, as fractures, ligament injuries, arthropathies, bone abnormalities, and tendinopathies. The authors describe and evaluate classic radiographic signs and explain how they correlate with MR imaging. The advantages and limitations of each technique are thoroughly discussed as well as other imaging modalities.

Metaphyseal Core Decompression of the Distal Radius for Early Lunate Necrosis

Background: Metaphyseal core decompression of the distal radius (MCD) is clinically effective in early lunate necrosis without changing individual wrist mechanics. Its concept is based on the induction of physiologic mechanisms known as physiologic fracture healing response. However, this biological concept does not yet have its place in the historically developed mechanical concepts about Kienböck's disease and requires more detailed clarifications to understand when a change of individual wrist mechanics might be unnecessary. Methods: Thirteen consecutive cases, Lichtman stage I (n = 1) or II (n = 12), confirmed by conventional MRI, were treated by MCD. Time off work, changes in magnetic resonance imaging of the lunate, as well as clinical outcome using modified Mayo wrist score were evaluated at final follow-up. Results: Return to work was at six (1-10) weeks after surgery. MRI controls at short-term generally demonstrated stop of progression and signs of bone healing. Independently from ulna variance complete signal normalization was observed in six and a distinct, yet incomplete decrease of lunate bone marrow edema and zones of fat necrosis was confirmed in further six cases after a mean of 21 (13-51) weeks. One patient had radiographic controls only, stating normal healing at 56 months. After a mean follow-up of 37 (12-70) months the clinical outcomes were excellent in eleven and good in two cases (mean 95% in modified Mayo wrist score). Conclusions: In stage I and II lunate necrosis MCD stops disease progression, it improves clinical symptoms and induces normalization of lunate bone signal alterations in MRI. Findings suggest that stage I and II lunate necrosis can be effectively treated without alterations of individual wrist mechanics. Future studies are necessary to readjust common concepts regarding Kienböck's disease, especially focusing on conservative therapy.

Imaging for Acute and Chronic Scaphoid Fractures

The scaphoid is the most commonly fractured bone in the wrist but 20% to 40% of scaphoid fractures are radiographically occult. Delayed or misdiagnosis can have significant consequences with late complications such as nonunion, malunion, or the development of avascular necrosis in the proximal pole. After initial negative radiographs, advanced cross-sectional imaging, including CT and MRI, ultimately may provide more accurate and rapid diagnosis than conventional radiography. With chronic fractures, the preferred modality depends on the clinical question. New techniques are evolving that will further advance imaging for diagnosis and treatment of scaphoid fractures.

Angular Stable Miniplate Fixation of Chronic Unstable Scaphoid Nonunion

Background  Around 5 to 15% of all scaphoid fractures result in nonunion. Treatment of long-lasting scaphoid nonunion remains a challenge for the treating surgeon. Healing of scaphoid nonunion is essential for prevention of scaphoid nonunion advanced collapse and the subsequent predictable pattern of radiocarpal osteoarthritis. Purpose  The purpose of this study was to investigate the feasibility of fixation of the scaphoid nonunion with a volar angular stable miniplate and cancellous bone grafting. We hypothesized that this technique could be successful, even in patients with previous surgery for nonunion and in patients with a long duration of nonunion. Patients and Methods  A total of 21 patients enrolled in a single-center prospective cohort study. Healing of nonunion was assessed on multiplanar computed tomography scan of the wrist at a 3-month interval. Functional outcome was assessed by measuring grip strength, range of motion, and by means of the patient-rated wrist and hand evaluation (PRWHE) questionnaire. Results  During follow-up, 19 out of 21 patients (90%) showed radiological healing of the nonunion. The range of motion did not improve significantly. Postoperative PRWHE scores decreased by 34 points. Healing occurred regardless of the length of time of the nonunion (range: 6-183 months) and regardless of previous surgery (38% of patients). Conclusion  Volar angular stable miniplate fixation with autologous cancellous bone grafting is a successful technique for the treatment of chronic unstable scaphoid nonunion, even in patients with long-lasting nonunion and in patients who underwent previous surgery for a scaphoid fracture. Rotational interfragmentary stability might be an important determining factor for the successful treatment of unstable scaphoid nonunion. Level of Evidence  Level IV.

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.