Osteochondral Lesions of the Talus - Allograft Repair



Co-Authors:  Milford H. Marchant Jr., M.D.; Mark E. Easley, M.D.; James A. Nunley II., M.D.



Osteochondral Lesions of the Talus Review
       
       Etiology
               - Primary Causes
                       - Trauma
                       - Ischemic Necrosis
                       - Embolic phenomenon
                       - Ossification Defects
               - Predisposing Factors
                       - Endocrine Disorders
                       - Peripheral vascular disease
                       - Genetic Predisposition?
                               - 10-25% Bilateral Lesions

       Evaluation
               - Presentation
                       - Acute inversion injury
                       - Chronic Ankle pain
                               +/- history of trauma
                               +/- instability
                       - Known History of OLT +/- prior treatment
               - Symptoms
                       - Pain
                       - Catching, grinding
                       - Feelings of instability and give-way episodes
       
       Diagnosis and Staging
               - Radiography
                       - X-ray – initial evaluation
                       - MRI – modality of choice for suspected lesions
                       - CT-Scan – modality of choice for known lesions
               - Arthroscopy
                       - Gold standard for diagnosis and determining optimal treatment modality

       Treatment Plan
               - Acute vs. Chronic symptoms
               - Radiographic Staging / Severity of Lesion
               - Location of the Lesion
               - Quality of Subchondral Bone
               - Ankle Instability
               - Prior Interventions

       Treatment Modalities
               - Non-Tissue Transplantation
                       - Activity Restriction
                       - Internal Fixation
                       - Arthroscopy
                               - Excision
                               - Curettage / Abrasion
                               - Drilling
                               - Micro-fracture

               - Tissue Transplantation
                       - Modalities
                               - Autologous Bone Grafting
                               - Autologous Chondrocyte Transplantation
                               - Carticel
                               - Osteochondral Autograft Transplantation (OATs)
                                       - Single Osteochondral Plug
                                       - Mosaicplasty
                               - Osteochondral Allograft Transplantation
                       - Benefits
                               - Provides the ability to fill in a larger defect
                               - Provides an articulating surface
                               - Prevents excessive weight bearing loads on the remaining portion of the talus which would accelerate ankle joint arthritis



Osteochondral Allograft Transplantation
       - Allograft Transplantation is proving to be beneficial for large osteochondral defects where duplication of the anatomy would be difficult with autologous tissue.
               - Osteochondral Autograft Transplantation Limitations
                       - Lesion size = Limited “extra” cartilage
                       - Only Carticel can fill irregular shaped lesions
                       - Flat surface required
                       - Attempts at angular repairs have been challenging

       - Allograft Talus is size matched = Custom fit
               - Able to treat the “shoulder lesion”
                       - Defect involving more than one articulating plane (Figure 1)

       - Allograft Benefits
               - In Fresh Allografts, Viable Chondrocytes are present within an intact Hyaline Cartilage Structure
                       - Arthroscopy and Mosaicplasty rely on fibrocartilage ingrowth
               - Shorter procedure
               - No second operative site for harvest
                       - Compared to OATs or Mosaicplasty
               - Single surgical procedure
                       - Compared to Autologous Chondrocyte Transplants (Carticel)

       - Allograft Risks
               - Transmission of Disease
               - Immune Response
               - Resorption and fragmentation of the graft
               - Procedure-based risk
                       - Osteotomy Non-union
                       - Post-op Arthritis

       - Specimens
               - Tissue Banks uphold strict guidelines and protocol established by American Association of Tissue Banks
               - Allograft procurement is performed in patients 18 - 45y within 24h
               - Transplantation occurs with 72 hours for fresh grafts
                       - Extension for up to 5 - 7 days has been reported
               - Donor patients are screened to eliminate possible disease transmission.
                       - Extensive medical and social histories  
                       - Multiple Cultures and serologic studies are performed
               - Articular cartilage is examined in a class-100 clean room
                       - Particle count < 100 particles per cubic foot of a size 0.5µ (micron) and larger.

       - Fresh vs. Fresh-Frozen Allograft
               - Storage
                       - Fresh grafts  = 4 degrees Celsius in Ringers lactate
                               +/- Antibiotics (Ancef, Bacitracin) added to the milieu
                               +/- Cryopreservative (dimethylsulfoxide DMSO, glycerol)
                       - Frozen Grafts  = -70  -80 degrees Celsius
                               + Cryopreservative
               - Differing Chondrocyte Viability

                       - Ohlendorf, et al (1996)
                               - Studied effects of Cryopreservation to -80 deg on Calf Cartilage using con-focal and conventional fluorescent microscopy
                               - Rapid freezing (2 deg/min)  = non-viable chondrocytes
                               - Slow freezing (0.5 deg/min)  = superficial chondrocyte layer viable only
                               - Slow freezing with cryopreservative  = superficial chondrocyte layer viable only
                               - Chondrocyte survival in cryopreserved osteochondral articular cartilage.

                       - Rodrigo, et al (1987)
                               - Compared rat chondrocyte viability in fresh vs. fresh-frozen osteochondral allografts
                               - Chondrocytes stored at 4 deg had 75% viability in 24 hours, and 47% at 48 hours
                               - Bone viability declined rapidly to 10% in 24 hours
                               - Significant decline in viable chondrocytes after freezing
                               - 8/10 specimens had 0% viability
                               - 2/10 showed almost 100% viability
                               - Immunogenicity also declined with freezing 
                               - Deep-freezing versus 4 degrees preservation of avascular osteocartilaginous shell allografts in rats.

               - Differing Immunogenic response
                       - Chondrocytes are imbedded in Hyaline Matrix
                       - By nature of location inside a synovial joint are somewhat immunopriveleged.1
                       - Presently, there are no requirements to immunologically match donor and host
                       - Acute rejection has thus far not been a clinical problem
                       - Marrow depletion is necessary via high pressure pulse lavage prior to implantation

                       - Stevenson, et al. (1989)
                               - Evaluated allograft cartilage implanted in dogs
                               - 4 categories based on Canine Leukocyte antigen matching and fresh vs. cryopreserved grafts
                                       - Antigen mismatched Frozen
                                       - Antigen mismatched Fresh
                                       - Antigen matched Frozen
                                       - Antigen matched Fresh
                               - No dog had any noticeable clinical abnormality
                               - All cartilage specimens were thinned
                               - Inflammatory response in synovium most severe in Fresh, Antigen mismatched allografts
                               - The worst specimen was seen in Frozen, antigen mismatched
                                       - Both histologically & biochemically
                               - Fresh Antigen matched grafts performed the best 
                               - The fate of articular cartilage after transplantation of fresh and cryopreserved tissue-antigen-matched and mismatched osteochondral allografts in dogs.

               - Allograft Choice
                       - Most Literature is leaning towards the use of Fresh Osteochondral Allograft
                               - Based on the viability of the chondrocytes and the maintenance of the cartilage matrix
                       - Grafts that have shown to be most viable when they are slow cooled to 4 deg Celsius and preserved

       - Outcomes
               - Literature has cited its use in Berndt and Harty Stage II, III, and IV lesions.

               - Thomas, et al (1997)
                       - Fresh-frozen Talar allograft
                               - Used during reconstruction for a benign osteochondral tumor of the talar dome.
                       - 18 months s/p surgery pt was participating in normal activity pain free.
                       - Repair of an osteochondral tumor of the talus utilizing a fresh-frozen cadaveric graft.

               - Gross, et al (2001)
                       - Evaluated 9 cases Clinically and Radiographically
                       - Pre-op:  All subjects had an area of Fragmentation and Collapse that could not be reattached
                               - Lesion at least 1 cm in diameter / 5 mm in depth
                               - All patients had prior procedures
                       - Average graft life = 9 years (3 – 19)
                       - 3/9  patients required fusions at 3, 5, 9 years out for graft fragmentation and collapse
                       - 6 pts with intact grafts required no assistive device
                       - 5 / 6 had no pain; 1 /6 had mild intermittant pain 
                       - Osteochondral defects of the talus treated with fresh osteochondral allograft transplantation.

               - Caylor and Pearsall (2002)
                       - Case report:  16-year-old female with 3 years pain after ankle sprain
                       - 2 Allograft Bone plugs used to treat a 18mm x 18mm lesion on posteromedial talus
                       - Post – op Protocol
                               - Immobilized 2 weeks
                               - ROM exercise only from 2 – 6 weeks
                               - Partial weight bear 6 – 12 weeks
                               - Full weight bear from 12 – 20 weeks
                               - Unlimited activity at 20 weeks
                       - F/U at 1 year, patient had no pain or limitations 
                       - Fresh osteochondral grafting in the treatment of osteochondritis dissecans of the talus.



Surgical Technique - Lateral
       - Care to avoid damage to the Sural n. & Peroneal artery posteriorly, & superficial peroneal n. anteriorly.
       - Removal of Osteophytes at Talofibular Joint
       - Fibular Osteotomy - Pre drill holes for plate
       - Removal of Osteochondral Lesion and Curettage
       - Preparation of Graft Site
       - Template (Figure 2)
       - Allograft Placement (Figure 3) 

       - Articulation Testing and Screw Fixation with Countersinking
       - Osteotomy Repair
       - Intra-operative Radiographs (Figures 4 & 5) 

Surgical Technique - Medial
- Utilizes Medial Malleolar Osteotomy (Figure 6)



Summary
       - Cartilage injuries and Osteochondral Lesions of the talus remain a challenge within Orthopaedics
       - MRI & CT scan is useful with identifying and defining pathology in patients with suspected lesion
       - Arthroscopy is the Gold Standard for diagnosis and treatment planning
       - For large, abnormally positioned lesions, or those that have failed prior intervention, Allograft Transplantation is a promising treatment modality
       - Further investigation and research is still needed in regards to
               - graft storage options
               - long term immunologic reactions
               - clinical outcomes



Original Text by Clifford R. Wheeless, III, MD.

Last updated by Data Trace Staff on Monday, January 7, 2013 2:40 pm