A Rare Case of Developmental Lateral Femoral Condyle Hypoplasia Managed with Lateral Distal Femoral Opening-Wedge Osteotomy using the Reversed Miniaci Method: A Case Report

Introduction

Genu valgum is a coronal plane deformity characterized by lateral deviation of the mechanical axis of the lower limb. Although physiological valgus alignment is common during childhood, persistent deformity in skeletally mature individuals can result in abnormal load transmission across the knee, increased contact stress within the lateral compartment, progressive cartilage degeneration, gait disturbance, and functional limitation ^[1,2]. When the deformity originates predominantly from the distal femur, correction at the site of deformity is important to restore limb alignment and joint biomechanics ^[3].

Distal femoral osteotomy is a well-established joint-preserving procedure for symptomatic valgus malalignment in young and active patients with preserved knee motion and limited degenerative changes ^[3,4]. By restoring the mechanical axis, distal femoral osteotomy redistributes load away from the lateral compartment, alleviates symptoms, and improves function. Lateral opening-wedge distal femoral osteotomy offers preservation of bone stock and limb length, intraoperative adjustability of correction, and the possibility of graft placement within the osteotomy gap ^[5].

Despite favorable clinical outcomes, cortical hinge fracture, loss of correction, delayed union, and non-union remain recognized concerns following opening-wedge osteotomy. Preservation of the cortical hinge is therefore important for construct stability and predictable healing ^[6,7,8,9,10]. Careful deformity analysis, pre-operative planning, and stable fixation are fundamental to successful correction. This report describes the surgical technique and clinical outcome of lateral opening-wedge distal femoral osteotomy with supplementary hinge stabilization for symptomatic genu valgum, emphasizing technical considerations that may enhance stability and promote reliable osteotomy union ^[9,10,11].

Case Report

A 17-year-old male presented to our outpatient orthopedic clinic with progressive right knee pain associated with a visible lower-limb deformity and an abnormal gait pattern. The patient reported gradual worsening of symptoms over time, with pain intensity reaching 7/10 on the Visual Analog Scale. Pain was aggravated by prolonged standing, walking, and physical activity, leading to significant limitations in activities of daily living. Due to progressive discomfort and instability during ambulation, he required a single-point cane for support.

Physical examination revealed marked right-sided genu valgum. Standing assessment demonstrated lateral deviation of the mechanical axis with an intermalleolar distance of 14 cm. Gait analysis showed an antalgic gait pattern. Knee range of motion was preserved, and ligamentous instability was detected. Neurovascular examination of the affected limb was unremarkable (Video 1).

Radiographic evaluation included standing anteroposterior, lateral, and long-leg weight-bearing hip-to-ankle radiographs. Coronal-plane deformity analysis demonstrated severe genu valgum with a tibiofemoral angle of 38°. Mechanical axis deviation measured 32 mm lateral to the center of the knee joint. Pre-operative deformity analysis revealed a mechanical lateral distal femoral angle of 65° and a medial proximal tibial angle of 100° (Fig. 1).

Pre-operative planning was performed to identify the site and magnitude of deformity and determine the correction required for restoration of normal lower-limb alignment. Clinical evaluation included assessment of knee range of motion, ligamentous stability, patellar tracking, and lower-limb rotational profile. The mechanical lateral distal femoral angle, medial proximal tibial angle, and joint line convergence angle were assessed. The reported normal reference values were 87° ± 3°, 87° ± 3°, and 0° ± 2°, respectively.

The reversed Miniaci method was used on long-leg standing radiographs to determine the correction angle and osteotomy parameters ^[5]. The desired post-operative weight-bearing line was planned to pass through the Fujisawa point, approximately 55% across the tibial plateau from the medial border. The correction angle, osteotomy level, hinge position, and required opening-wedge height were determined from this plan (Fig. 2).

Results

Post-operative radiographs demonstrated restoration of the mechanical axis restored to near-neutral alignment with maintenance of correction during follow-up. The osteotomy site showed satisfactory apposition without evidence of cortical hinge fracture or implant-related complication. Radiographic union was achieved within the expected follow-up period. The patient demonstrated improvement in gait pattern, resolution of symptoms, and improved cosmetic appearance. Functional evaluation at 6 months showed an American Knee Society Score >85, indicating excellent functional recovery. No infection, loss of correction, implant loosening, or neurovascular deficit was observed (Fig. 4, Table 1).

Discussion

Distal femoral osteotomy remains an established joint-preserving procedure for correction of symptomatic genu valgum and restoration of lower-limb alignment in young and active patients. Accurate deformity analysis and correction planning are essential for achieving favorable outcomes ^[3,4,5]. Both medial closing-wedge and lateral opening-wedge techniques can provide satisfactory clinical and radiographic correction. Lateral opening-wedge osteotomy offers advantages, including preservation of limb length and flexibility in achieving the desired correction.

The reversed Miniaci method is a graphical planning technique that allows calculation of the correction angle by transferring the desired post-operative mechanical axis onto a full-length weight-bearing radiograph ^[12]. The method uses the intended weight-bearing line and simulates correction around the planned osteotomy hinge point, facilitating estimation of the opening-wedge size and correction angle while reducing the risk of undercorrection or overcorrection ^[10,11].

Preservation of hinge integrity is critical because the intact cortex contributes to rotational stability and maintenance of the planned correction during early healing. Hinge disruption can lead to loss of correction, delayed union, non-union, and compromised fixation stability. The present case emphasizes the value of a deliberate hinge-protection strategy using a Steinmann pin during lateral opening-wedge distal femoral osteotomy.

The case also demonstrates the importance of comprehensive radiographic analysis when deformity involves more than one segment. The pre-operative Mechanical lateral distal femoral angle and medial proximal tibial angle indicated contributions from both the distal femur and proximal tibia. The decision to correct the distal femoral component with an opening-wedge osteotomy was based on the deformity analysis and the planned mechanical-axis correction.

The principal limitation of this report is that it describes a single patient and therefore cannot establish comparative efficacy of the technique. Longer follow-up and additional cases would be required to determine the reproducibility of the observed functional and radiographic outcomes.

Conclusion

Lateral opening-wedge distal femoral osteotomy planned with the reversed Miniaci method provided accurate correction of severe genu valgum in this patient. Deliberate medial cortical hinge protection, controlled wedge opening, stable lateral plate fixation, and appropriate rehabilitation were associated with maintenance of alignment, radiographic union, and satisfactory functional recovery. Further clinical experience is required to establish the reproducibility of this approach in similar deformities.

Clinical Message

In severe valgus deformity, accurate deformity localization and mechanical-axis planning are essential. A reversed Miniaci plan combined with controlled wedge opening, medial hinge protection, stable plate fixation, and appropriate rehabilitation can achieve reliable correction and osteotomy union in a symptomatic adolescent.

References

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About the Authors

• 

  Samir Gajanan Zade

• 

  Hisham Ali Khan

• 

  Pagidala Mehraj

• 

  Shubham Mohod

• 

  Shaharyar Elahi

• 

  B Meghana