Osteochondritis Dissecans Ankle and Knee



Osteochondritis Dissecans Ankle and Knee


Dennis E. Kramer

Melissa A. Christino



Ankle Arthroscopy/Arthrotomy and Treatment of OCD Lesion


Background: Lesion Location



  • 10% to 25% bilateral


  • Posteromedial lesions: 60%



    • May be traumatic or nontraumatic


    • Caused by plantarflexed ankle subjected to inversion and external rotation


    • Typically nondisplaced, cup-shaped, deep lesions (more bony involvement)


  • Anterolateral lesions: 40%



    • Usually traumatic, associated with “sprain”


    • Anterolateral talar dome impacts face of fibula with ankle in dorsiflexion and inversion stress applied


    • Shallow, wafer-shaped, displaced lesions (less bony involvement)


Operative Indications



  • Nonoperative treatment best for



    • Young patients


    • Small lesions


    • Asymptomatic lesions


  • Operative indications



    • Symptomatic patients with detached or unstable osteochondritis dissecans (OCD) lesions


    • Symptomatic patients approaching physeal closure (within 6-12 months) and unresponsive to nonoperative management


    • Symptomatic stable lesions that have not healed in 6 to 9 months



Equipment



  • Small joint arthroscopy set


  • Ankle distractor set


  • Nonsterile thigh-high tourniquet


  • 0.045 C-wires


  • Wire driver


  • Fluoroscopy (optional)


  • Ankle positional drill guide (similar to anterior cruciate ligament [ACL] drill guide)



  • Fixation devices



    • Absorbable



      • Tacks—example: SmartNail (ConMed Linvatec, Utica, NY)


      • Screws—example: Bio-Compression screw(Arthrex, INC, Naples, FL)


    • Nonabsorbable



      • Headless metal compression screws


  • If arthrotomy necessary



    • Army-navy retractors


    • Freer elevator


    • Tiny curettes


  • If bone graft necessary



    • 3.2 mm drill


    • Curved curettes


Positioning



  • Supine


  • Thigh-high tourniquet to allow for knee flexion if arthrotomy necessary


  • Foot at end of bed so surgeon can dorsiflex ankle with abdomen and have good posture during arthroscopy


Surgical Approach


Ankle Arthroscopy



  • Exsanguinate leg and inflate tourniquet


  • Insufflate ankle with 5 to 10 mL normal saline


  • Anterolateral portal lateral to peroneus tertius


  • Anteromedial portal medial to tibialis anterior (TA) (Figure 34.1)


  • Standard diagnostic ankle arthroscopy


  • Debride synovium to facilitate visualization


  • Use imaging combined with arthroscopic visualization to identify and assess lesion



    • Important to have 3-dimensional imaging (eg, magnetic resonance image [MRI]) visible during case to help interpret arthroscopic findings








  • Use ankle distractor system as necessary to facilitate visualization (Figure 34.2)



    • Note how ankle distraction device causes simultaneous plantarflexion of the ankle, which facilitates view of the talar cartilage more posteriorly


  • Palpate with probe to assess for softness and stability (Figure 34.3)


  • Evaluate the OCD



    • Probe to test overlying cartilage


    • Often will be unstable in talus OCD


  • Assess your access and decide if you need an arthrotomy


  • Low threshold for arthrotomy to best evaluate the stability of the lesion













Ankle Arthrotomy



  • Posteromedial lesions are often inadequately assessed via arthroscopic means, even with ankle distraction, as typically the unstable portion of the lesion is the posterior border of the lesion



    • For posteromedial lesions, have a low threshold to perform a posteromedial arthrotomy to evaluate and assess the lesion and decide how to proceed


  • Anterolateral lesions can often be assessed arthroscopically,



    • however, if considering fixation, have low threshold to proceed with arthrotomy to better access and assess the lesion to allow for perpendicular drilling/fixation


Posteromedial Arthrotomy (posteromedial arthrotomy ( video) Video)



  • Necessary for posteromedial lesions in skeletally immature patients for whom medial malleolar osteotomy is contraindicated


  • However, posteromedial arthrotomy is also adequate for skeletally mature patients in whom osteotomy is an option but has higher morbidity. Especially in cases of debridement, drilling, or fixation where perfect perpendicular access is not required


  • If perfect perpendicular access to the lesion is required (for example, planned osteochondral autograft transfer system [OATS] procedure), then posteromedial arthrotomy may not be adequate, and medial malleolar osteotomy may be necessary


  • Remove arthroscopic equipment


  • Place leg in figure 4 position


  • Foot and ankle can be elevated on a nonsterile or sterile bolster to help exposure and keep the contralateral leg out of the way


  • Make 3 cm incision posteromedial ankle curved about the posteromedial tibia at the level of the joint line (Figure 34.4)








  • Identify the following:



    • Posterior tibialis (PT) tendon—just off posteromedial border of tibia


    • Flexor digitorum longus (FDL) tendon—deeper and just posterior to PT


    • Neurovascular bundle—just posterior to FDL


    • Flexor hallucis longus (FHL) tendon lies posterior to neurovascular bundle and is not routinely visualized


  • Dissect in the interval between PT and FDL (Figure 34.5)


  • Army-navy retractor pulls FDL and neurovascular bundle posteriorly


  • Second army navy retractor pulls PT anteriorly


  • Identify posterior capsule deep in this interval


  • Incise capsule—look for joint fluid/arthroscopic fluid that is released following arthrotomy


  • Use arthroscopic shaver to excise the posteromedial synovium just under the capsule and facilitate visualization of the talus


  • Have assistant push ankle into maximal dorsiflexion


  • Identify and assess the lesion with probe


Anteromedial Arthrotomy



  • Less commonly necessary as most medial lesions are posterior on the talus


  • Rarely, a combined posteromedial + anteromedial approach is necessary to fully access the medial OCD lesion


  • Extend anteromedial portal proximally (Figure 34.6)













  • Dissect medial to TA


  • Make arthrotomy


  • Army-navy retractors to retract TA laterally


  • Excise fat pad to expose the anteromedial talus


  • Hold ankle in maximal plantar flexion


  • Expose and assess the lesion


Anterolateral Arthrotomy



  • Extend the anterolateral arthroscopic portal proximally (Figure 34.7)


  • Dissect lateral to peroneus tertius


  • Protect superficial peroneal nerve, which may be identified proximally in the incision


  • Make arthrotomy








  • Excise synovium to expose anterolateral talus


  • Hold ankle in maximal plantarflexion to expose lesion (Figure 34.8)


  • If exposure is still inadequate, can place freer elevator over the top of talus to attempt to sublux talus anterior


  • If exposure is still inadequate, can incise the anterior talofibular ligament (ATFL) off of the fibula to aid with anterior subluxation of the talus



    • This would necessitate repair of ATFL during closure as well as prolonged immobilization/protection postoperatively to allow for healing


Posterolateral Arthrotomy



  • Rarely necessary as most lateral lesions are anterior


  • Consider prone positioning


  • 4 cm incision centered between Achilles tendon and lateral malleolus


  • Identify and protect sural nerve


  • Dissect in interval between Achilles tendon medially and peroneal tendons laterally


  • Incise the posterolateral capsule


  • Excise synovium of posterolateral ankle joint to improve visualization of talus


  • Hold ankle in full dorsiflexion to expose posterolateral talus


Lesion Assessment



  • Use arthroscopic probe to assess the size, location, and stability of the lesion (Figure 34.9)


  • Grade/stage the lesion based on surgical appearance combined with imaging classification













Berndt and Harty Radiographic Staging



  • Stage 0—marrow edema on MRI



    • Stage I—compressed subchondral bone


    • Stage II—partially attached fragment/subchondral cyst


    • Stage III—complete detachment/nondisplaced


    • Stage IV—detached fragment displaced within joint


Hepple (1999) MRI Staging (T2)



  • Stage 1 Articular cartilage damage only


  • Stage 2a Cartilage injury, underlying fracture, edema


  • Stage 2b No edema


  • Stage 3 Detached with rim signal but nondisplaced


  • Stage 4 Displaced


  • Stage 5 Subchondral cysts (Figure 34.10)


Cheng (1995) Arthroscopic Staging



  • Stage A Smooth, intact, ballotable


  • Stage B Rough surface, stable


  • Stage C Fibrillation, fissuring, stable (see Figure 34.3)


  • Stage D Flap present, unstable


  • Stage E Loose nondisplaced fragment, unstable


  • Stage F Displaced fragment, unstable (Figure 34.11)


Treat Based on Overall Assessment of Lesion Stability



  • Intact, stable—Drilling


  • Flap lesion, cartilage breach, unstable—Hinge, curette, consider bone graft, add fixation


  • Detached—Fixation versus excision


  • Unsalvageable: Excision, microfracture versus cartilage resurfacing








Arthroscopic Trans-Articular Drilling (Figure 34.12)



  • For stable lesions with intact overlying articular surface


  • Creates channels for revascularization


  • Can go transarticular or retrograde extra-articular


Technique



  • Goal: Penetrate lesion and pass through underlying subchondral bone


  • Probe the cartilage to identify the soft spot corresponding to the OCD lesion


  • Mark out the lesion with probe


  • Medial talar lesions



    • Arthroscope positioned through anterolateral portal


    • 0.45 mm C-wires placed percutaneously, freehand



      • Start 1 cm proximal to standard anteromedial portal site, adjust as needed


      • Make sure C-wire stays medial to TA at all times


      • Aim for anterior portion of the medial talus OCD lesion


      • Plantar flex ankle


      • Determine if exposure is adequate


      • Drill to depth of approximately 2 cm


      • Place multiple drill holes several millimeters apart