Trần Khôi Luân Trần Quốc Doanh, Nguyễn Ảnh Sang, Vũ Quốc Hưng, Nguyễn Văn Bình, Bùi Văn Phúc, Võ Thành Nhơn, Đỗ Hải Nam [1]
1. Orthopedic and Trauma Institute, Military Hospital 175, Ho Chi Minh City, Vietnam
Mục Lục
Abstract
Introduction: Scaphoid fractures are the most frequently encountered fractures of the carpal bones, representing 50-80% of these injuries. They often present with nonspecific symptoms, which can lead to diagnostic challenges. Although most scaphoid fractures heal with proper treatment, approximately 10% may result in nonunion, and around 3% may progress to avascular necrosis (AVN) of the proximal pole. Addressing this complication requires surgical intervention to promote bone healing, restore the scaphoid’s structure, relieve pain, and enhance wrist functionality. Vascularized bone grafting, particularly using a pedicled graft from the dorsal region of the distal radius, has shown promise in treating AVN of the scaphoid proximal pole. This report discusses two cases managed with this technique at Military Hospital 175.
Case presentation: We present two patients treated for scaphoid proximal pole AVN using vascularized bone grafts at the Upper Limb Department of Military Hospital 175. The surgical approach involved harvesting a pedicled vascularized bone graft from the dorsal side of the distal radius, utilizing either the Zaidemberg or Sotereanos method. Postoperative evaluations indicated successful bone healing and significant pain relief in both patients. Additionally, they achieved substantial recovery of wrist and hand function, with 90% of the contralateral wrist’s range of motion and 85% of grip strength restored during follow-up assessments.
Conclusion: This case series highlights that, with appropriate indications, vascularized bone grafting from the dorsal distal radius can provide positive early outcomes for patients with AVN of the scaphoid proximal pole. The procedure demonstrated both anatomical and functional improvements, allowing patients to return to their work and daily activities. These results support the need for further research through larger, prospective studies to confirm the long-term benefits of this technique.
Case 1 Presentation
Case 2 Presentation
Discussion
Treating scaphoid nonunion, especially when complicated by avascular necrosis, poses a considerable challenge for orthopedic surgeons. A systematic review by Munk et al. involving 5,246 patients found that non-vascularized bone grafts (NVBGs) have a union rate of 84% for scaphoid nonunion generally, which is statistically similar to the 91% union rate achieved with vascularized bone grafts (VBGs). However, in cases with avascular necrosis, the success rate of NVBGs drops significantly to 47%, as indicated by a systematic review conducted by Merrell et al. This suggests that NVBGs have limited osteogenic potential compared to the 88% success rate of VBGs. Studies in animals and biomechanics have demonstrated that VBGs possess superior biological and mechanical properties, such as the preservation of osteocytes and osteoblasts, which may enhance revascularization, improve bone remodeling, accelerate graft integration, and maintain bone mass, ultimately fostering better bony union. In a prospective randomized study by Ribak et al. involving 46 patients, VBGs from the distal radius were shown to result in a significantly higher bone fusion rate of 89.1% compared to 72.5% for NVBGs. Furthermore, another randomized prospective study by Caporrino et al. with 75 patients reported that VBGs resulted in earlier bone healing by 12 days with the same fusion rate..
Numerous studies have explored various vascularized bone graft (VBG) techniques to tackle the challenge of avascular necrosis. Among these are pedicled grafts from the distal radius, which are based on the volar carpal artery, the pronator quadratus, the 1,2 intercompartmental supraretinacular artery (ICSRA), and the dorsal capsule. More recently, free vascularized bone grafts from the iliac crest and the medial femoral condyle have been investigated.
In the first case, we utilized the dorsal pedicled graft based on the 1,2 ICSRA for treating proximal scaphoid fractures with associated avascular necrosis. This technique, originally described by Zaidemberg et al. in 1991, achieved a 100% union rate in 11 patients with scaphoid nonunion and has since gained widespread acceptance among hand surgeons as a preferred treatment option for scaphoid nonunion.
The vascular anatomy of the 1,2 ICSRA was initially detailed by Sheetz et al. and further examined by Waitayawinyu et al. in cadaver studies. This artery is consistently present in 94-100% of cases, originating from the radial artery and traveling superficially over the extensor retinaculum between the first and second extensor compartments. It has an average pedicle length of 22.5 mm and supplies 3-7 perforating vessels from the pedicle to the cortical bone. The authors suggested that a 10 mm bone graft positioned 8 mm proximal to the articular surface would incorporate most of the perforators, and the pedicle length would be adequate for graft transposition to the proximal scaphoid. Nonetheless, the success rate of union has varied across studies when using Zaidemberg’s technique for managing avascular necrosis in proximal scaphoid nonunion. Boyer et al. observed a 60% union rate in 10 patients with avascular necrosis, while Chang et al. reported a 50% union rate in 24 cases. They noted a significant link between humpback deformity and surgical failure, indicating a limitation of the 1,2 ICSRA graft in restoring scaphoid geometry due to its relatively short length and limited biomechanical support. In contrast, Waitayawinyu et al. reported excellent results, achieving a 93% union rate in 30 patients with avascular necrosis treated with the 1,2 ICSRA graft, along with concomitant radial styloidectomy in all cases, emphasizing a technical tip to prevent pedicle kinking.
In the second case, we employed a vascularized graft technique based on the dorsal capsule of the wrist, as thoroughly detailed by Sotereanos et al. and Papatheodorou et al. This reverse-flow graft is supplied by the 4th extensor compartment artery, which was found to be consistently present in a cadaveric study by Sheetz et al., affirming its dependability. Key benefits of this graft include straightforward dissection and harvesting without the need for intricate dissection of small vessels or microsurgical anastomosis. Its proximity to the scaphoid fracture site and a short rotation arc (10-30 degrees) reduce the risk of vascular compromise from pedicle kinking, which is a common issue with the 1,2 ICSRA graft. Consequently, radial styloidectomy is not necessary. Due to its location, this pedicled graft has also been used for treating lunate osteonecrosis in Kienböck’s disease. However, like the 1,2 ICSRA and other dorsally based grafts, it is not suitable for correcting humpback deformity, which requires a volar approach, and its effectiveness may be compromised if the patient has had previous dorsal wrist surgery or severe injury. Sotereanos et al. reported a bone union rate of 76.9% in 13 patients, with an average union time of 13 weeks (range, 6-23 weeks). In a more extensive study, Papatheodorou et al. treated 64 patients using a similar technique, achieving an 86% union rate at an average of 12 weeks (range, 6-24 weeks) post-surgery. These outcomes are comparable to other VBG techniques, which report union rates ranging from 60% to 100%, and are particularly promising given that their studies focused exclusively on cases with avascular necrosis.
For Patient A, bone union was achieved at the three-month follow-up. By the 12-month follow-up, wrist extension improved from 45 to 60 degrees, radial deviation increased from 5 to 10 degrees, grip strength improved by 27% from 30 kg to 38 kg, pain was completely relieved, and Mayo’s wrist function score improved by 23% from 65 to 80.
Patient B showed bone union on radiographs at the four-month follow-up after a three-month period of immobilization followed by one month of physiotherapy. During evaluation, wrist tenderness during hyperextension decreased from a VAS score of 2 to 1, but some tenderness persisted. There was a 10-degree decrease in wrist flexion and extension, and grip strength decreased by 13% compared to preoperative levels. There was no improvement in Mayo’s wrist score, which could be attributed to the extended immobilization period and may improve with further physiotherapy sessions, especially since bone union was confirmed.
The time to union in our cases aligns with the average reported in other studies involving dorsally based grafts, which range from 5 to 40 weeks, including studies by Steinmann et al. (11.1 weeks), Chang et al. (15.6 weeks), Lim et al. (14 weeks), and Morris et al. (11.4 weeks). However, some studies have reported longer union times, with Boyer et al. noting a mean time of 4.6 months and Waitayawinyu et al. observing a mean time of 5.1 months.
There is variability in studies regarding improvements in range of motion and grip strength. Some clinical studies, such as those by Malizos et al. and Lim et al., found that patients experienced pain relief but no significant improvements in range of motion or grip strength. In contrast, other studies reached different conclusions. A prospective cohort study by Barrera-Ochoa et al. reported an overall gain of 20 degrees in each range of motion set compared to preoperative levels, along with a significant improvement in grip strength, with an average increase of 41% from 52.9% to 95.3% relative to the contralateral side. Similarly, Rahimnia et al. found that postoperative radial-ulnar deviation improved significantly, and grip strength in patients who achieved union was 73% compared to the healthy contralateral hand, significantly higher than those who did not achieve union. They concluded that achieving union helped restore grip strength. Similar results were noted in studies using dorsal capsular-based grafts, with Papatheodorou et al. and Sotereanos et al. both reporting significant improvements in postoperative wrist extension, flexion, and grip strength. The observed differences among studies can be attributed to various factors, including differences in study design, patient chronicity, proportion of avascular necrosis, fixation methods, postoperative immobilization techniques, union assessment criteria, and the surgeon’s experience.
At the final follow-up, Patient A’s Mayo’s wrist score improved from 65 to 80, consistent with findings from other studies, where authors noted differences in individual categories but agreed on significant improvements in overall functional outcomes, including pain, return to work, range of motion, and grip strength.
Conclusion
Various vascularized grafts have proven effective in treating avascular necrosis linked to scaphoid nonunion. Without conclusive evidence favoring one particular graft, careful diagnosis and classification have allowed for successful outcomes using vascularized bone grafts taken from the dorsal aspect of the distal radius at Military Hospital 175. These grafts have shown promising initial results in terms of bone union and postoperative wrist function, facilitating patients’ return to work and daily activities. This success provides a strong basis for future prospective studies.
