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Arthroscopic Preparation and Internal Fixation of an UnstableOsteochondritis Dissecans Lesion of the Knee

Christopher L. Camp, M.D., Aaron J. Krych, M.D., and Michael J. Stuart, M.D.

Abstract: We present our arthroscopic technique for fixation of an unstable osteochondritis dissecans (OCD) lesion. Thistechnique includes arthroscopic evaluation of cartilage and bone quality of the OCD fragment, hinging open the lesion,debridement of fibrous nonunion tissue, reducing the fragment, and obtaining multi-point compression screw fixation.This technique avoids the morbidity of an open arthrotomy and should be considered when treating an unstable OCDlesion with adequate bone for fixation.

steochondritis dissecans (OCD) is characterized by

Osubchondral bone avascular necrosis and subse-quent deterioration of the overlying articular cartilage.1,2

This can lead to pain, effusion, mechanical symptoms,and early joint degeneration. With an annual incidenceof 15 to 29 per 100,000 population, OCD lesions area significant source of knee pain in high-demand skele-tally immature and mature athletes.3,4 Although theexact etiology is unclear, the multiple contributingfactors include ischemia, repetitive trauma, failure ofgrowth-center ossification, inflammatory processes, andgenetic predisposition.5-9 In the skeletally immaturepatient, comprehensive nonoperative treatment withactivity modification, physical therapy, and oral analge-sics may be a viable option. Stable, juvenile OCD lesionshave improved spontaneous healing rates comparedwith adult OCD lesions.10 However, surgical interventionis required for refractory juvenile OCD lesions and allsymptomatic adult OCD lesions.11

Surgical options include drilling, in situ fixation,open reductioneinternal fixation, and more advancedrestorative procedures such as marrow stimulation,

From the Department of Orthopedic Surgery and Sports Medicine Center,ayo Clinic and Mayo Foundation, Rochester, Minnesota, U.S.A.The authors report the following potential conflict of interest or source ofnding: M.J.S. receives support from Arthrex: paid consultancy for productevelopment not related to this submitted work. Stryker and USA Hockeyoundation: funds are provided for research support not related to thisbmitted work.Received May 23, 2013; accepted July 10, 2013.Address correspondence to Michael J. Stuart, M.D., Mayo Clinic, 200 First

t SW, Rochester, MN 55905, U.S.A. E-mail: stuart.michael@mayo.edu� 2013 by the Arthroscopy Association of North America2212-6287/13340/$36.00http://dx.doi.org/10.1016/j.eats.2013.07.005

Arthroscopy Techniques, Vol 2, No 4

osteochondral autograft transfer, osteochondral allo-graft transplantation, and combined bone grafting withautologous chondrocyte implantation. Depending onthe degree of complexity of the surgery, these proce-dures may be performed through open or arthroscopictechniques. When feasible, arthroscopy is desirableover open techniques because of decreased operativemorbidity and quicker recovery. We describe anarthroscopic technique used to treat an unstable OCDlesion of the femoral condyles. During this arthroscopicprocedure, the unstable fragment is hinged open, thebony bed is prepared by removing fibrous tissue, and thelesion is fixed with Bio-Compression screws (Arthrex,Naples, FL).

TechniqueIn our experience, the described technique works

well for stable OCD lesions with intact cartilage afterfailed nonoperative management or for unstable OCDlesions that have adequate bone for internal fixation.The preoperative radiographs and magnetic resonanceimaging are valuable to assess the bone quality andthickness of the OCD fragment and to identify any loosebodies (Figs 1 and 2).12 In our experience, 3 to 4 mm ofnon-fragmented bone is required to achieve stableinternal fixation. Each potential surgical option shouldbe discussed with the patient before embarking onthe diagnostic arthroscopy. If a large bone fragment isidentified and deemed amenable to fixation (thepreferred technique), osteochondral preservation withinternal fixation is performed. If the OCD lesion hasinsufficient bone stock or fragmentation, arthroscopicremoval is performed. If the secondary osteochondrallesion size is small, we proceed with osteochondralautograft transfer. If the osteochondral defect is too large,

(November), 2013: pp e461-e465 e461

Fig 1. Initial presenting right kneeradiographs showing an OCD lesion ofthe lateral femoral condyle on (A)posteroanterior (PA) flexion and (B)lateral views.

Fig 2. Initial (A) sagittal and (B) cor-onal T2-weighted magnetic resonanceimages obtained before initiation ofnonoperative treatment, showing theOCD lesion of the lateral femoralcondyle of the right knee. One shouldnote the increased linear signal at thebase of the lesion present on bothviews. (C) Sagittal and (D) coronalT2-weighted magnetic resonance imagesof the knee obtained after 5 monthsof nonoperative treatment showingminimal improvement or intervalhealing. We find magnetic resonanceimaging very helpful in measuring theamount of bone present on the OCDlesion and also if there is any frag-mentation present.

e462 C. L. CAMP ET AL.

Fig 3. Arthroscopic view of OCD lesion of lateral femoralcondyle from inferomedial viewing portal.

Fig 5. Arthroscopic view (from inferomedial viewing portal)of base after removal of fibrous nonunion tissue. The bleedingbone confirming vascularity should be noted.

ARTHROSCOPIC FIXATION OF KNEE OCD LESION e463

a size-matched fresh osteochondral allograft transplantis planned as a future staged procedure.The knee is examined under general anesthesia and

then prepared and draped in the standard fashion. Atourniquet is placed high on the thigh but is not inflatedduring the arthroscopic portion of the procedure. Thesurgical technique is detailed in Video 1. A thoroughdiagnostic arthroscopy is performed, including assess-ment of the suprapatellar pouch, medial and lateralgutters, and posteromedial and posterolateral compart-ments for any possible loose bodies. In addition, the

Fig 4. Arthroscopic view (from inferomedial viewing portal)of subchondral bone after lesion has been hinged open.

other articular cartilage surfaces, menisci, and ligamentsare examined.In this particular case, examination of the lateral

femoral condyle from an inferomedial viewing portalshowed a large OCD fragment involving the middle andposterior thirds of the condyle (Fig 3). The articularsurface of the lesion was largely intact with the excep-tion of a fissure along the anterior margin. We find itimportant to carefully inspect the entire periphery of theOCD fragment because a cleft or fissure is often found. Inthis case the fragment was ballotable with a blunt probe

Fig 6. Final view (from inferomedial viewing portal) of OCDlesion showing multi-point screw fixation.

Fig 7. Radiographs of knee obtained 12weeks postoperatively showing satis-factory restoration of articular surfaces:(A) anteroposterior view and (B) lateralview.

e464 C. L. CAMP ET AL.

inserted through the inferolateral portal. At that time,the fragment was deemed unstable and the decision wasmade to hinge open the fragment to prepare the base forfixation. A knife was used to open the lesion at itsanterior fissure. The posterior attachment was left intact,which allowed the fragment to be hinged open to accessthe base of the lesion (Fig 4).Once the base was fully exposed, attention was

directed to preparing the bed for fixation. The sub-chondral bone was covered with a layer of fibroustissue that is typical in unstable OCD lesions. This tissuewas removed with a curette and a motorized shaver.After all the fibrous tissue was removed, the inflow wasturned off to confirm adequate bony bleeding from theentire bed (Fig 5). After subchondral bone preparation,

Table 1. Technical Pearls for Treating OCD Lesions of Knee

Steps

Assess bone with MRI � Ensure 3 to 4 mm of� Assess possible fragme� Identify loose bodies

Discuss all intraoperative possibilitieswith patients preoperatively

� Fix stable or reducible� If fragment is �2 to 3� If fragment is �2 to 3

Open lesion as hinge � Lateral femoral condy� Medial femoral condy

Prepare lesional base � Thoroughly debride a� Ensure adequate base

Ensure secure anatomic fixation � Create accessory porta� Use K-wires for stabil� Use multi-point screw� Recess screws below a

MRI, magnetic resonance imaging; OAT, osteochondral autograft transligament.

attention was turned to removing fibrous tissue fromthe undersurface of the osteochondral fragment bylightly scraping the surface with a curette. The fragmentwas then reduced to the bony base, and anatomicreduction was confirmed by flexing and extending theknee to visualize the entire lesion.The OCD fragment was then provisionally fixed with

a single K-wire through the inferolateral portal. Afterthis, an accessory trans-patellar tendon portal wascreated to allow perpendicular access to the fragment.The lesion was fixed in place by use of a total of 4 Bio-Compression screws. Each fixation site was drilled,measured, and tapped before placement of the screws.Each compressive screw was countersunk 2 to 3 mmdeep to the articular cartilage surface, with great care

Pearls

adequate bone to allow adequate compressive fixationntation of lesion

lesions of adequate quality (preferred method of treatment)cm2 and cannot be fixed, excise and transfer OAT plug(s)cm2 and cannot be fixed, excise and plan for staged OCAle lesions can be hinged on posterior cartilagele lesions can be hinged on PCL soft-tissue attachmentll fibrous tissuepreparation by turning off inflow and observing bone bleedingls as needed to obtain perpendicular fixationization during fixationfixationrticular surface but not through the fragment compromising fixation

fer; OCA, osteochondral allograft transplant; PCL, posterior cruciate

ARTHROSCOPIC FIXATION OF KNEE OCD LESION e465

taken not to over-advance the screw and lose fixationof the fragment. The K-wire was then removed, and thelesion was tested for stability with a blunt probe (Fig 6).

Postoperative RehabilitationAfter surgery, patients are restricted to toe-touch

weight bearing for the first 6 weeks. Emphasis is placedon edema reduction to encourage early pain controland quadriceps activation. Continuous passive motionis instituted on the first postoperative day at 0� to 30� ofrange of motion, with instructions to advance to 0� to120� as able. After 6 weeks, new radiographs are ob-tained; the continuous passive motion is discontinued;and the patient is allowed to begin partial weightbearing, advancing to full weight bearing as toleratedwithout crutches by 12 weeks. Strength training in thefirst 6 weeks focuses on straight-leg raises and quadri-ceps sets for quadriceps strengthening. This is advancedas tolerated after the initial 6-week postoperativeperiod, and new radiographs are obtained at the12-week postoperative mark (Fig 7).

DiscussionKnee pain due to OCD is a common reason that

patients present to orthopaedic surgeons.3,4 In young,skeletally immature patients, these lesions can often besuccessfully treated with a comprehensive nonoperativeregimen of restricted weight bearing and activity modi-fication to offload the affected area until healingoccurs.10 However, patients with persistent symptomsdespite these modalities typically require surgical inter-vention.13 A number of surgical options, ranging fromsimple in situ arthroscopic fixation to open articularcartilage restoration and limb realignment procedures,have shown efficacy in appropriately selected patients.14

If possible, it is desirable that these lesions be fixed ina manner that maximizes healing potential whileminimizing recovery time and time out of sport foryoung athletes. Many cartilage restoration techniquesare available today, but healing of the native bone andcartilage is certainly the most desirable. In skeletallyimmature patients, Kocher et al.6 found an osseousintegration rate of 84.6%. With regard to choice offixation, bioabsorbable screws have the advantageof not necessitating removal and do not negativelyaffect subsequent magnetic resonance imaging studies.However, metal headless compression screws can alsobe used. In our experience, we have found that metalscrews with a longer guidewire can be successfully usedand later removed arthroscopically as well.This technical note describes an arthroscopic technique

for treating OCD lesions of the knee that includes as-sessment of stability, hinged opening or partial detach-ment of the lesion, preparation of the subchondral bone

base, fragment reduction, andmulti-point fixation. It hasthe benefits of being able to treat unstable OCD lesions inan arthroscopic manner that avoids the morbidity of anopen arthrotomy. Diligent preparation of the base, whichis confirmed by visualization of bony bleeding, improvesthe healing potential of these lesions. Although thistechniquemay not be technically feasible for all lesions ofthe knee, it can effectively treat most lesions of themedial and lateral femoral condyles through standardarthroscopy portals with selective additional accessoryportals as needed. Risks of the procedure potentiallyinclude persistent pain and fragment instability due toinadequate base preparation, nonanatomic reduction, orfixation failure. These risks can be minimized whenproper surgical techniques are used (Table 1).

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