Combined Treatment of Recurrent Patellofemoral Instability Associated with Genu Valgum and a Patellar Osteochondral Lesion.

Authors:

Rubén D. MD
Resident in Orthopedics and Traumatology. Universidad Pontificia Bolivariana, Medellin. Colombia.
Alejandro Jaramillo Q. MD
Orthopedic Surgeon, Knee and Shoulder Surgery. Salud Sura, Medellin. Colombia.
Paula A. Sarmiento R. MD
Orthopedic Surgeon, Knee Surgery. Clínica del Campestre, Medellin. Colombia.

Corresponding author: E-mail: rubenarper@gmail.com

All the authors declare no conflict of interest.

INTRODUCTION

Lateral patellar dislocation predominantly affects young and physically active patients, with an estimated incidence ranging from 5.8 to 77 cases per 100,000 person-years ^[1]. Following a first-time dislocation, approximately 15% to 44% of patients experience recurrent instability ^[2]. The risk of recurrence increases in the presence of predisposing anatomical factors, including trochlear dysplasia, patella alta, an increased tibial tubercle–trochlear groove distance, and coronal or rotational malalignment ^[2,3].

Medial patellofemoral ligament (MPFL) reconstruction is one of the principal surgical procedures used to treat recurrent patellofemoral instability ^[4]. However, isolated MPFL reconstruction may be insufficient when relevant mechanical risk factors, such as genu valgum, remain uncorrected because valgus alignment increases the lateralizing force acting on the patella and adversely affects patellofemoral tracking ^[5]. Distal femoral varus osteotomy can restore mechanical alignment and decrease lateralizing forces; nevertheless, redislocation rates of up to 20% have been reported when osteotomy is performed without an additional patellar stabilization procedure ^[6]. Therefore, combined coronal-plane correction and MPFL reconstruction may be appropriate in selected patients ^[5,7].

Patellar dislocations may also result in osteochondral lesions and intra-articular loose bodies. Osteochondral injuries occur in approximately 30% of acute patellofemoral dislocations and may contribute to persistent pain, functional impairment, and the development of patellofemoral osteoarthritis ^[12]. Osteochondral allograft transplantation provides simultaneous restoration of the articular cartilage and subchondral bone while avoiding the donor-site morbidity associated with autograft harvesting ^[13].

The purpose of this video is to present the combined treatment of recurrent patellofemoral instability, genu valgum, and a patellar osteochondral lesion using a biplanar lateral closing-wedge distal femoral varus osteotomy, osteochondral allograft transplantation, MPFL reconstruction, and arthroscopic loose-body removal.

TECHNIQUE DESCRIPTION

A 34-year-old woman presented with progressive pain and functional limitation after two episodes of left lateral patellar dislocation. Physical examination demonstrated asymmetric left genu valgum, joint effusion, a knee range of motion from 0° to 130°, and a positive patellar apprehension test. No clinically relevant rotational malalignment was identified. The J-sign and ligamentous and meniscal tests were negative.

Diagnostic imaging demonstrated Dejour type A trochlear morphology, a tibial tubercle–trochlear groove distance of 13.6 mm, and a Caton–Deschamps index of 1.03. A grade IV osteochondral lesion involving the medial patellar facet and an intra-articular loose body were identified. Standing long-leg radiographs demonstrated a mechanical-axis deviation of 10.3 mm, a lateral distal femoral angle of 83.5°, and a medial proximal tibial angle of 89°.

The surgical procedure was performed as follows:

1. Arthroscopic evaluation and loose-body removal
Diagnostic arthroscopy was performed to evaluate patellar tracking, confirm the location and extent of the osteochondral lesion, and identify any associated intra-articular abnormalities. The intra-articular loose body was subsequently identified and removed.

2. Coronal-plane correction planning
The correction was planned to use standing long-leg radiographs. A 7° mechanical-axis correction was selected and performed through a lateral closing-wedge distal femoral varus osteotomy.

3. Biplanar distal femoral osteotomy
A biplanar distal femoral osteotomy was performed with an approximate osteotomy length of 44 mm. A 5-mm bone wedge was removed, and the osteotomy was progressively closed until the planned correction was achieved. Coronal alignment was verified fluoroscopically before definitive osteotomy fixation.

4. Osteochondral lesion preparation
The full-thickness osteochondral lesion of the medial patellar facet was outlined and debrided to obtain stable margins. Two circular recipient sockets, each measuring 8 mm in diameter, were prepared while preserving as much surrounding healthy cartilage as possible.

5. Osteochondral allograft transplantation
Two 8-mm osteochondral allograft plugs were harvested and adjusted according to the depth of the recipient sockets. The plugs were inserted using press-fit fixation, ensuring that the graft cartilage remained flush and congruent with the surrounding patellar articular surface.

6. MPFL reconstruction
MPFL reconstruction was performed using a semitendinosus tendon allograft. The graft was fixed to the patella using two 3-mm threaded anchors. The anatomical femoral attachment of the MPFL was identified using anatomical landmarks and fluoroscopic guidance. Femoral fixation was performed using a bioabsorbable interference screw.

7. Final assessment of patellar tracking
Graft tension was adjusted while avoiding medial over constraint of the patella. Arthroscopy was subsequently used to evaluate graft tension, patellar position, and patellofemoral tracking throughout knee flexion and extension.

RESULTS

At the 12-month follow-up, the patient demonstrated appropriate lower-limb alignment and a knee range of motion from 0° to 130°. She returned to her usual daily activities and experienced no recurrent patellar dislocation, clinically significant pain, or procedure-related complications. The International Knee Documentation Committee Subjective Knee Form score improved from 54 points preoperatively to 92 points at 12 months. 

Previous clinical studies have shown that distal femoral osteotomy combined with MPFL reconstruction can provide reliable correction of lower-limb alignment, improve knee function, and reduce recurrent instability in patients with genu valgum ^[5,7,9]. Potential advantages of a closing-wedge osteotomy include avoidance of bone grafting, a lower risk of altering patellar height, reduced irritation of the iliotibial band, and favorable bone-healing characteristics ^[10]. Furthermore, the biplanar configuration increases the available bone-contact area and may allow simultaneous correction of coronal and rotational deformities when both are present ^[11].

For the treatment of osteochondral lesions of the knee, osteochondral allograft transplantation has demonstrated favorable clinical outcomes, with reported graft survival of approximately 86% at 5 years ^[13]. In the present case, simultaneous treatment of patellofemoral instability, coronal malalignment, and the patellar osteochondral lesion resulted in patellar stability, functional improvement, and restoration of lower-limb alignment at short-term follow-up.

PATIENT CONSENT

The patient provided written informed consent for the publication of the clinical information, diagnostic images, and audiovisual material related to this case. Her identity and confidentiality were protected.

REFERENCIAS

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• Combined Treatment of Recurrent Patellofemoral Instability Associated with Genu Valgum and a Patellar Osteochondral Lesion.