Delayed Structural Failure Following Medial Femoral Condyle Flap Reconstruction of the Distal Radius: A Report of Two Cases

Abstract

Vascularized medial femoral condyle (MFC) flap transfer is a technique that may be used to reconstruct recalcitrant distal radius nonunion. Although union rates are high, the flap provides thin cortical bone requiring rigid fixation. The long-term strengthening and structural integrity of the MFC flap bone remains understudied. We describe two cases of delayed structural failure following distal radius MFC reconstruction. Two patients underwent distal radius reconstruction using vascularized corticocancellous MFC flaps stabilized with spanning fixed-angle volar plates. Both achieved radiographic union. Clinical records and radiographs were retrospectively reviewed following low-energy injuries. Late failure occurred 7 and 9 years after flap incorporation, involving deformity through the MFC bone segment. The spanning plates bent without evidence of screw loosening or hardware failure. These cases highlight a rare pattern of delayed structural failure following MFC reconstruction. Radiographic union alone may not predict long-term structural durability. Rigid fixed-angle fixation may influence load distribution and adaptive remodeling.

The free medial femoral condyle flap (MFC) is a widely used reconstructive solution for salvaging recalcitrant upper-extremity nonunions, including distal radius nonunions with segmental bone loss, infection, and/or surgical failure.^1,2 The MFC is a corticocancellous flap supported by robust periosteal and endosteal blood supply.³

In distal radius nonunion reconstructions, long fixed-angle volar plates are used to provide mechanical stability and support early motion.⁴ These constructs offer reliable fixation in compromised bone and are stiffer than native bone. Contemporary biomechanical studies demonstrate that volar locking plates function as internal fixators—offering strong resistance to axial, bending, and torsional loads—and permit early mobilization.⁵ However, while rigid volar fixed-angle constructs are effective for early stabilization, their long-term effect on load distribution and bone remodeling remains incompletely understood.

We report two cases of delayed structural failure following successful corticocancellous MFC reconstructions of the distal radius. Each patient initially achieved radiographic union and functional recovery, but later experienced failure at the reconstructed segment without hardware loosening, raising considerations regarding long-term mechanical behavior of unicortical bone flaps under rigid fixation. Written informed consent for publication of this case report and accompanying images was obtained from the living patient and from the next of kin of the deceased patient.

Case 1

In 2014, a 44-year-old woman presented with painful left distal radius malunion after fracture 18 years prior. Radiographs demonstrated 10° of dorsal tilt and 3−4 mm of ulnar positive variance, with radiocarpal and ulnar-sided wrist pain (Fig. 1A–C). She underwent corrective distal radius osteotomy with volar locking plate fixation.

Figure 1.

Case 1: Preoperative radiographs showing distal radius malunion with dorsal angulation (∼10°) and ulnar positive variance before corrective osteotomy. A Posteroanterior, B lateral, and C oblique views.

The patient reported persistent wrist pain at the osteotomy site, and a computed tomography scan obtained 7 months after surgery confirmed nonunion (Fig. 2A–C). Revision surgery was performed using a vascularized MFC bone flap measuring approximately 2.5 cm × 2 cm × 2 cm. A long stainless steel volar locking plate was used to span the defect. The cortical surface of the MFC bone was positioned on the radial column of the radius, orthogonal to the plate construct. Intraoperative fluoroscopy and radiographs from postoperative day 10 (Fig. 3A–C) confirmed restoration of radial height and volar angulation with stable fixation. Eight weeks after surgery, radiographs demonstrated early flap incorporation with maintained alignment (Fig. 4A–C), and a computed tomography scan 4 months after surgery confirmed flap incorporation and cortical continuity (Fig. 5A, B).

Figure 2.

Case 1: Computed tomography scan 7 months after corrective osteotomy showing persistent nonunion prior to MFC reconstruction. A Coronal and B, C sagittal views.

Figure 3.

Case 1: Postoperative day 10 radiographs following vascularized MFC flap reconstruction of the distal radius showing volar plate fixation and flap position. A Oblique, B posteroanterior, and C lateral views.

Figure 4.

Case 1: Radiographs at 8 weeks following MFC flap reconstruction showing early flap incorporation and maintained alignment of the distal radius. A Oblique, B posteroanterior, and C lateral views.

Figure 5.

Case 1: Computed tomography 4 months after MFC flap reconstruction showing cortical continuity across the reconstructed distal radius defect. A Coronal and B sagittal views.

Seven years later, at age 51, the patient sustained a ground-level fall on ice. Radiographs demonstrated an apex volar-angulated, extra-articular distal radius fracture through the site of her MFC flap, with deformation of the volar plate but no evidence of screw loosening or implant breakage (Fig. 6A–D). During operative intervention, the removed hardware was noted to be firmly adherent to the bone. The fracture plane appeared fresh, with high-quality cancellous bone proximally and distally, and no features suggestive of prior nonunion. The fracture was treated with open reduction and internal fixation using direct bone-to-bone coaptation and revision fixed-angle volar plate fixation (Fig. 7A–C). Based on intraoperative findings of a thin dorsal cortex, there was concern that limited cortical remodeling contributed to local mechanical vulnerability. To facilitate radial shortening and optimize compression, a distal ulnar resection was performed, and cancellous bone was packed around the fracture site. The distal radius fracture healed uneventfully. One year after this surgery, a dual x-ray absorptiometry scan revealed a lumbar spine T-score of −2.5 and femoral neck T-score of −2.1, indicative of osteoporosis; she was then referred for bone health care.

Figure 6.

Case 1: Radiographs obtained after a fall 7 years after reconstruction, demonstrating an extra-articular distal radius fracture through the old MFC flap segment, with apex volar angulation and deformation of the volar plate but intact screw purchase on bone. A Posteroanterior, B lateral, and C oblique views. D Photograph of the deformed volar plate removed at revision.

Figure 7.

Case 1: Intraoperative fluoroscopic images showing the MFC flap site and removal of the deformed volar plate. A−C Sequential fluoroscopic projections.

Case 2

In 2010, a 73-year-old right-hand-dominant woman presented with an infected nonunion of the left distal radius following prior open reduction and internal fixation, consistent with chronic osteomyelitis of the distal metadiaphysis. She underwent staged reconstruction beginning with removal of loose hardware, debridement of the nonunion site resulting in a 4-cm segmental defect, and placement of an antibiotic-impregnated cement spacer (Fig. 8A, B).

Figure 8.

Case 2: Prereconstruction radiographs showing antibiotic-impregnated cement spacer within the distal radius defect following debridement for chronic osteomyelitis. A Posteroanterior and B lateral views.

Reconstruction was performed following spacer removal and repeat debridement, leaving a 4.8-cm bony defect. This was reconstructed using a vascularized corticocancellous MFC, cancellous autograft from the distal femur, and a 12-cm stainless steel volar plate. The cortical component of the MFC was positioned dorsally with the fixation construct applied on the radius’ volar aspect. The flap incorporated, and fracture healing was confirmed radiographically (Fig. 9A–C). The patient achieved painless wrist and forearm motion with no evidence of recurrent infection or hardware loosening.

Figure 9.

Case 2: Postoperative radiographs after vascularized MFC reconstruction and volar plate fixation demonstrating complete healing of the reconstruction, restoration of length, and alignment of the distal radius. A Lateral, B posteroanterior, and C oblique views.

Nine years later, at age 82, the patient sustained a ground-level fall, resulting in visible deformity through the reconstructed segment with preserved range of motion (Fig. 10A, B). Radiographs demonstrated dorsal angulation of the distal radius, with the volar plate and screws remaining intact, in contact with the volar cortical bone and without evidence of hardware loosening. Both the bone and plate appeared deformed, suggesting load transmission through the reconstruction rather than isolated implant failure.

Figure 10.

Case 2: Radiographs 10 years after MFC reconstruction following a fall, demonstrating late dorsal angulation through the reconstructed distal radius segment with intact volar plate fixation. A Lateral and B oblique views.

The late deformity following a low-energy fall raised concern that the MFC reconstruction may not have achieved full long-term cortical strength. The injury was interpreted as a late mechanical failure of the MFC segment rather than a fracture through the adjacent radius bone. Given the patient’s minimal symptoms and preserved function, she was managed nonoperatively with splinting and hand therapy.

Discussion

The terminology “structural bone grafting” and “nonstructural bone grafting” was common in the lexicon of the reconstructive hand surgeon before the advent of modern fixed-angle devices. Before locking screw fixation, intercalary defects were reliant on a combination of conventional fixation and the structural stability afforded by the intercalary bone graft/flap. Advances in internal fixation constructs now enable surgeons to rely on the plating construct for stability and consider nonstructural grafting in settings that would previously require structural flaps.

In scenarios where vascularized bone transfer is planned, the structural support of fixed-angle fixation may influence the surgeon to use a nonstructural MFC flap where they might have previously used a more structural fibular flap. The MFC provides a unicortical flap that is nonstructural. The single cortex harvested with this flap is pliable and thin. While this serves the surgeon well when molding the flap around an atrophic nonunion site, it does not provide structural stability. While the cancellous nature of the MFC yields rapid healing rates, the surgeon should continue to be vigilant for the long-term need for structural strength.

Structural support of locking screw fixation during the healing period is desirable; however, stress shielding may limit the ability for the bone flap to hypertrophy or provide cortical strength in future years. These two cases of delayed structural failure raise important questions about the long-term structural integrity of vascularized corticocancellous bone flaps, particularly when stabilized with rigid fixed-angle hardware constructs. Both patients achieved radiographic union with functional recovery. Yet, each sustained a fracture years later localized to the reconstructed segment, without evidence of plate fracturing or screw loosening. This suggests successful biological incorporation does not guarantee restoration of physiologic bone strength.

The MFC vascular pedicle branches into smaller vessels invested within the periosteum of the single cortical surface.⁶ To avoid compression of the periosteal vessels by the plate construct, the flap’s cortical surface is typically positioned orthogonally to the plate or on the opposite side of the radius. In both presented cases, the surface facing the plate was cancellous. The subsequent dorsally angulated deformities through the reconstructed segment suggest load was transmitted through the reconstructed bone rather than adjacent to the plate’s edge.

Long-term stress shielding from rigid volar fixation may have limited remodeling within the reconstructed segment, contributing to reduced mechanical resilience. This is consistent with established models of stress shielding, wherein rigid internal fixation reduces local strain and suppresses adaptive cortical remodeling.^7,8 Using high-resolution peripheral quantitative computed tomography and microfinite element analysis, Nia et al.⁷ demonstrated that after volar plate removal, cortical remodeling continues for over a year with a 52% increase in cortical thickness and 24% increase in axial stiffness. In contrast, trabecular architecture remained impaired, suggesting that cancellous regions subjected to prolonged stress shielding may sustain long-lasting deficits in microarchitecture, even after hardware is removed.⁷

Commonly used fixed-angle volar plates have elastic moduli far exceeding that of native bone.^4,9 While providing early stability, they may divert physiologic load away from the flap−host interface, limiting the mechanical stimulus required for long-term adaptive remodeling.^8,10 In the absence of implant removal or more compliant fixation, these underloaded regions may persist as zones of mechanical vulnerability.

Both patients had bone health comorbidities (osteoporosis for case 1 and prior osteomyelitis/infection for case 2) that may have increased the risk for baseline fracture. However, each reconstruction remained intact for years and failed only through the reconstructed bone segment, with the surrounding host bone intact. The combination of localized deformity and intact hardware suggests failure arose from the flap’s insufficient mechanical durability. Consideration should be given to the long-term interaction between flap composition, fixation stiffness, and load distribution. Potential strategies include supplementing reconstruction with additional cortical bone, selecting lower-stiffness implants (eg, carbon fiber-reinforced polyetheretherketone or porous titanium),⁹ selecting bone flaps with greater cortical composition (ie, fibula, iliac crest), or removing hardware after union to promote adaptive remodeling.⁷

These two cases describe similar patterns of radius fractures through regions reconstructed by MFC flaps several years prior. The MFC flap is powerful in achieving osseous healing; however, achieving radiographic union does not ensure the subsequent restoration of normal mechanical strength. In high-risk cases, the surgeon may consider tactics to improve long-term remodeling and durability.

Ethics declaration

Written informed consent to take part in the study and to publish the article has been obtained from all participants or their legal representatives. The privacy rights of participants have been observed.

This study was performed in compliance with relevant laws, regulatory frameworks and guidelines where the research took place. Ethics committee approval was not required under relevant laws and institutional guidelines. No IRB review and approval was needed. Only 5 or more cases require IRB review/approval, and this case series studied 2 cases.

This research follows the CARE guidelines and the CARE checklist.

Patient Consent

Written informed consent for publication of this case report and accompanying images was obtained from the living patient and from the next of kin of the deceased patient.

Conflicts of Interest

Given his role as Deputy Editor-in-Chief of Journal of Hand Surgery Global Online, Dr Giladi had no involvement in the peer review of this article and has no access to information regarding its peer review. Full responsibility for the editorial process for this article was delegated to Dr Fowler. No benefits in any form have been received or will be received by the other authors related directly to this article.