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    Management of End-Stage Patellofemoral Post-Traumatic Chondromalacia with Fresh Osteochondral Allograft

    A 40-year-old with a history of recurrent patellar dislocation resulting in post-traumatic patellofemoral chondromalacia has persistent anterior knee pain and swelling 2 years after patellofemoral chondroplasty and synovectomy. Will fresh osteochondral allograft transplantation offer pain relief?

    Authors

    Zaira Chaudhry, MPH, and Robert W. Frederick, MD

    Disclosures

    The authors have no disclosures relevant to this article.

    Background

    Articular cartilage disease of the patellofemoral joint presents a rather unique challenge in orthopaedic practice due to the tissue’s limited potential for spontaneous healing and the highly complex biomechanical forces experienced within the patellofemoral compartment during weight-bearing activity. [1]

    Patellofemoral cartilage injuries may result from: [2]

    • Direct trauma to the anterior knee
    • Patella fracture
    • Patellar instability (dislocation and subluxation)
    • Dysplasia (trochlea)

    Patellofemoral cartilage injuries may present with the following symptoms:

    • Anterior knee pain at rest
    • Activity-related pain
    • Crepitation with active range of motion
    • Difficulty with kneeling, squatting, climbing stairs, and rising from a low chair
    • Catching or locking with knee extension

    Chondral lesions of the knee are quite common, especially in young, active patients. A study of 31,000 consecutive knee arthroscopies found chondral defects in 63% of patients regardless of the surgical indication. [3]

    Most chondral lesions are localized to the medial femoral condyle, with the patella being the second most common site. [4] Moreover, in 1 study, 95% of patients with acute patellar dislocation had intraoperative evidence of chondral or osteochondral defects involving the patella. [5]

    Case Presentation

    A 40-year-old male presented with persistent left anterior knee pain and swelling 2 years post-arthroscopic patellofemoral chondroplasty, subtotal synovectomy, and synovial biopsy revealing mild-to-moderate chronic synovitis.

    He reported that the pain, which varied in severity from 3/10 to 7/10, significantly limited his work as well as activities of daily living and sometimes necessitated taking hydrocodone at night so he could sleep. He also reported a sense of insecurity with certain motions and positions of his left knee, particularly when negotiating stairs.

    The patient’s history was significant for recurrent lateral patellar dislocation and subluxation. He sustained an initial injury to his left knee 20 years earlier resulting in acute lateral patellar dislocation. Following this injury, the patient had mild intermittent discomfort and modified his activity to some degree. Three years ago, he experienced a repeat dislocation followed by a second repeat dislocation approximately 1 month later.

    The patient was initially treated conservatively, which included activity modification, rehabilitation, intra-articular corticosteroid and viscosupplementation injections, and a lateral J knee sleeve. However, the patient’s discomfort persisted and he subsequently opted for diagnostic knee arthroscopy.

    During his initial left knee arthroscopic surgery, the patient was found to have severe grade IV post-traumatic arthritis affecting the majority of his patella articular surface and the lateral half of his trochlea. In addition, there was evidence of a diffuse synovial process; a synovial biopsy was positive for pigmented villonodular synovitis (PVNS).

    The patient was referred to a total joint specialist for consideration of patellofemoral replacement. Due to the abnormal synovium and his relatively young age, he was not found to be an appropriate candidate.

    Physical Examination

    • BMI: 32.74 kg/m2
    • 1+ effusion
    • Range of motion: 5-130° with mild discomfort at extremes
    • 3+ patellofemoral crepitation with active knee extension
    • Lateral patellar tracking (mildly positive J-sign)
    • Positive patellofemoral compression sign
    • Q angle of approximately 20°
    • Mild quadriceps atrophy

    Differential Diagnosis

    • Post-traumatic patellofemoral chondromalacia/degenerative arthritis
    • Patellar instability
    • Patellar/trochlear dysplasia
    • Osteochondritis dissecans

    Imaging

    Plain radiographs (weight-bearing AP, lateral, sunrise, PA flexion) demonstrated (Figures 1-2):

    • Tricompartmental degenerative arthritis
    • Degeneration of the lateral patellofemoral articulation and the lateral compartment of the left knee, patella alta
    • Insall-Salvati ratio of 1.66 (normal reference range: 0.8 to 1.2)
    • Evidence of previous Osgood-Schlatter disease

    Figures 1-2. Preoperative lateral radiograph of the left knee (left) demonstrates degeneration of the lateral patellofemoral articulation and patella alta. Preoperative sunrise radiograph of the left knee (right) demonstrates degeneration of the patellofemoral articulation and lateral tracking of the patella.

    MRI scan of the left knee demonstrated grade IV posttraumatic changes affecting the lateral patellofemoral articulation as well as a subchondral cyst (Figure 3). Both valgus alignment and a mildly elevated tibial tuberosity-trochlear groove (TT-TG) distance were also noted, using a distance of < 15 mm as the normal TT-TG reference value.

    Figure 3. Preoperative sagittal T1- and T2-weighted images of the left knee demonstrate grade IV patellofemoral cartilage degeneration and a subchondral cyst.

    Diagnosis

    • Lateral patellofemoral compartment post-traumatic chondromalacia/degenerative arthritis
    • Recurrent lateral patellar subluxation, remote history of recurrent patellar dislocation

    Treatment

    The patient underwent fresh osteochondral allograft transplantation of the patella and lateral trochlea with medialization tibial tubercle osteotomy, Z-plasty lengthening of the lateral retinaculum, and anterior compartment fasciotomy.

    • The patient was placed supine under general anesthesia.
    • Using a bolster, his left lower extremity was placed in a neutral position, and a well-padded tourniquet was placed on his proximal thigh.
    • Z-plasty lengthening was used to perform the lateral parapatellar arthrotomy. An incision was made through the superficial lateral retinacular layers adjacent to the patella and extending proximally into the distal quadriceps tendon and distally along the lateral border of the patellar tendon.
    • An anterior compartment fasciotomy was performed using Bovie electrocautery, with the anterior compartment musculature dissected posteriorly about 1 cm with a Cobb elevator.
    • A tibial tubercle osteotomy was performed using an AO 2.5-mm drill bit passed from proximal lateral to distal medial just posterior to the anterior tibial cortex. These holes were connected with a half-inch Lambotte osteotome to perform the osteotomy while keeping the distal periosteal hinge intact. Once it was able to be plastically deformed medially, where the proximal end was pushed medially approximately 15 mm, it was provisionally fixed with a smooth K-wire.
    • The patella was everted and marked. Post-traumatic grade IV changes were noted along the majority of the patella articular surface (except the superomedial portion) and the lateral half of the trochlea (Figure 4).
    • Once the sizing block was positioned on the lateral facet of the patella, the perpendicular guide pin was drilled. The trephine was placed over it, and the reamer was used to ream to the appropriate depth (approximately 6 mm).
    • Next, the 22.5-mm patellar allograft was placed on the cutting jig and, once the cylindrical reaming hole was properly positioned, the donor graft drill was passed through the patella after marking the 12 o’clock position.
    • The graft was then trimmed to the appropriate thickness, and the bony portions of the graft were smoothed with a rongeur (Figure 5).
    • Grafton and allograft chips were used to achieve the appropriate height of the graft resulting in a secure fit.
    • The patella osteochondral allograft was gently press-fit into place and settled to the appropriate depth (Figure 6).
    • Two 18-mm trochlear allografts were prepared for the trochlear lesion in a similar fashion to the technique outlined above. The sizing block was placed perpendicular to the lesion, the guide pin was advanced, the trephine was placed over it, and the reamer was used to ream to the appropriate depth.
    • The femoral condyle osteochondral allograft was placed on the cutting jig and proper positioning of the harvesting reamer was used to obtain the 18-mm diameter graft, followed by trimming to the appropriate depth and smoothening with a rongeur before the graft was press-fit into place.
    • A second plug was placed in a similar fashion distal to the first without overlap (Figure 7).
    • The Z-plasty lengthening was reapproximated by suturing the more lateral superficial layer to the deeper medial layer, and approximately 2 cm of lengthening was achieved.
    • The distal quadriceps tendon that had been opened in its midline was reapproximated with #2 FiberWire sutures in a figure-of-eight fashion.
    • Distally, the tibial tubercle osteotomy was secured with two AO 3.5-mm screws.

    Figure 4. Intraoperative photograph of the left knee following lateral parapatellar arthrotomy demonstrates grade IV post-traumatic changes affecting the patella and lateral trochlea.

    Figure 5. Intraoperative photograph of the size-matched patellar osteochondral allograft following harvest of the donor plug alongside the recipient’s patella after reaming.

    Figure 6. Intraoperative photograph of the recipient’s patella after press-fitting the donor osteochondral allograft into the reamed area.

    Figure 7. Intraoperative photograph of the recipient’s patella and lateral trochlea after the donor osteochondral allografts were press-fit into the reamed areas.

    Postoperative Care

    Immediately following surgery, the patient was placed in a knee brace locked in full extension.

    Partial weight-bearing with crutches was allowed initially (50% at 0-2 weeks, 75% at 3 weeks), and full weight-bearing was allowed at 4 weeks. Early range of motion of the knee (0-45°) was allowed for the first 3 weeks, followed by 0-90° by 6 weeks and then progression to full range of motion as tolerated.

    The brace was discontinued at 4 months.

    Most Recent Follow-up

    At the 4-month follow-up, the patient stated that he was “feeling great overall” and reported sleeping well and not using any pain medication. Range of motion was 5-125° with minimal pain. Trace patellofemoral crepitation was detected with active knee extension.

    Discussion

    This case highlights the challenges of treating a young patient with end-stage patellofemoral post-traumatic chondromalacia. Although conservative measures, such as physical therapy and intra-articular corticosteroid or viscosupplementation injections, may provide relief for some patients, others may require surgical intervention to achieve long-term relief. Physical therapy has been shown to produce modest short-term improvements in knee pain scores and quadriceps muscle strength in patients with patellofemoral osteoarthritis, although its long-term effectiveness has not been well documented. [6]

    Alternative surgical treatment options include autologous chondrocyte implantation (ACI) or matrix-induced ACI (MACI), ACI or MACI in combination with an allograft, and patellofemoral replacement. However, the patient was not deemed to be an appropriate candidate for the latter. While favorable results have been reported in patients treated with ACI for patellofemoral full-thickness chondral defects, a decline in clinical scores was noted in patients with multiple and patellar lesions. [7]

    Many autologous chondrocyte implantation procedures are currently performed in 2 stages to allow for cell culture, which is costly and necessitates additional recovery time. In general, these procedures are most appropriate for younger patients with acute, full-thickness osteochondral lesions. Moreover, given the advanced degenerative changes noted in this patient, ACI/MACI procedures were not considered to be appropriate treatment options.

    Fresh osteochondral allograft (OCA) transplantation is a single-stage technique that is indicated for primary treatment of large (>4cm2) chondral or osteochondral defects, as well as for salvage of failed cartilage repair. [8]

    This procedure can be used to treat:

    • Post-traumatic arthritis
    • Osteochondritis dissecans
    • Focal osteonecrosis
    • Fracture malunion

    When used to treat post-traumatic arthritis, OCA transplantation may delay or eliminate the need for future knee arthroplasty, which is an important consideration for young, active patients.

    However, it is important to note that this procedure can be very challenging from both a technical and logistical standpoint. Unique challenges associated with fresh OCA transplantation include: [8]

    • Tissue availability
    • Serologic testing for infectious disease
    • Graft storage and size matching
    • Cell viability
    • Immunologic graft response

    Osteochondral allograft tissue is harvested within 12 to 24 hours of the donor’s death, and it is recommended that the time between harvest and transplantation not exceed 28 days. [8] Allograft storage beyond 28 days is associated with decreased chondrocyte viability. [9] Moreover, there is a direct correlation between chondrocyte viability and the clinical efficacy of OCA transplantation. [9]

    The graft matching and procurement process is complex, as it entails ensuring that the harvested donor graft matches the size, shape, and precise location of the defect. The mediolateral dimension of the tibia is used for sizing. [7] Moreover, once a match is found, the graft must undergo processing and serologic testing.

    In addition to being technically demanding, this procedure is associated with significant costs. Unfortunately, the use of fresh osteochondral allografts for bipolar patellofemoral lesions may not be covered by some insurance companies. However, with proper indications and documentation of failed conservative treatment, the senior author has not experienced issues obtaining approval for fresh OCA transplantation as a salvage procedure.

    Although reports on the outcome of OCA transplantation limited to the patellofemoral joint are variable, 1 study found that 10% of knees initially treated with fresh OCA transplantation required further allografting, and the rate of subsequent knee arthroplasty was 10%. [10]

    The existing literature suggests that, depending on the amount of tissue that is transplanted, fresh OCA transplantation limited to the patellofemoral joint has the potential to provide arthritic symptom relief, improve function, and delay knee arthroplasty. [11]

    Patient characteristics associated with favorable outcomes following OCA transplantation include body mass index less than 35 kg/m2 and increased preoperative activity levels. [12]

    Although fresh OCA transplantation may be an effective procedure for treating patellofemoral chondral lesions, there is a need for further research on long-term outcomes as well as optimization of graft viability and healing.

    Author Information

    Zaira Chaudhry, MPH, and Robert W. Frederick, MD, are from The Rothman Institute, Philadelphia, Pennsylvania.

    Sports Medicine Section Editor, Rothman Institute Grand Rounds

    Sommer Hammoud, MD

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