Arthroscopic or open fixation of an unstable osteochondral fragment | advanced
- The most critical distinction is between juvenile OCD (open physes) and adult OCD (closed physes). Juvenile lesions heal far more often with non-operative management (up to 50-60% with protected loading alone) and have a better prognosis after fixation. Always establish skeletal maturity before planning treatment.
- The classical location is the lateral aspect of the medial femoral condyle (60-70% of cases), but OCD also occurs on the lateral femoral condyle, patella and trochlea — the location changes surgical access and the angle of screw placement.
- Lesion stability is the central surgical decision point. MRI instability signs are a high-signal T2 fluid rim around the fragment, a breach of the overlying articular cartilage, and a cyst greater than 5 mm beneath the fragment. Arthroscopic probing is the definitive stability test — an unstable fragment lifts from the bed with gentle probe pressure.
- The native osteochondral fragment must be preserved whenever possible in young patients. A well-fixed, healed native fragment with congruent hyaline cartilage is biomechanically superior to marrow stimulation, osteochondral autograft transfer, or autologous chondrocyte implantation.
When & Why
Indication. Surgical fixation of an osteochondritis dissecans lesion is offered for an unstable or detached fragment in a knee that is symptomatic — mechanical locking, catching or effusions — or a lesion that has failed a fair trial of non-operative care. Two axes drive every decision: skeletal maturity (open versus closed physes) and lesion stability (probe-tested at arthroscopy). The single most important preoperative question is whether the physes are open or closed. Absolute indications - An unstable or detached OCD lesion confirmed on arthroscopic probing (Dipaola grade II-IV) in a symptomatic patient.
- A symptomatic loose body from a displaced OCD fragment with mechanical locking or catching.
- Failed non-operative management after 3-6 months of protected weight-bearing and activity modification in a juvenile patient with an unstable lesion.
- Progressive lesion enlargement or instability on serial MRI despite non-operative treatment. Relative indications - A symptomatic stable lesion (Dipaola grade I) in a skeletally mature adult with persistent pain despite 3-6 months of non-operative management.
- A lesion greater than 2 square cm with high T2 signal but intact cartilage, where fixation may prevent detachment.
- A patient approaching skeletal maturity with an unhealed juvenile lesion — fixation before physeal closure may improve healing potential.
- Adult OCD with a viable fragment and a contained bed, where fixation is preferred over marrow stimulation when the fragment is salvageable. Contraindications. Absolute: an active knee infection (defer fixation until it resolves); a completely necrotic fragment with no attached subchondral bone and no articular cartilage integrity — fixation will fail, so proceed to salvage (microfracture, OATS or allograft). Relative: advanced degenerative change (Outerbridge grade IV) elsewhere in the knee, where fixation will not alter the degenerative cascade; poor compliance with postoperative weight-bearing restrictions; and a very small lesion (less than 1 square cm) that has already healed. The healing argument that sets the threshold. Juvenile OCD with open physes heals in roughly 50-60% of cases with protected weight-bearing and activity modification over 3-6 months, because the open physis and the juvenile subchondral bone provide growth, remodelling and vascularity. Adult OCD (closed physes) heals in only about 20-30% with protected loading. This is why a stable juvenile lesion is managed without surgery first, and why the threshold for fixation is lower in adults. The one decision tree. Every pathway turns on the same two axes:
Protected weight-bearing, activity restriction and serial MRI every 3-4 months. Around 50-60% heal without surgery — the evidence-based default.
Arthroscopic fixation with bioabsorbable pins or physeal-sparing headless screws that stay within the epiphysis, plus subchondral drilling.
Arthroscopic or open fixation with metal headless compression screws, countersunk fully beneath the articular surface.
Salvage by lesion size: microfracture, OATS, ACI or osteochondral allograft (see Aftercare and Complications).
Arthroscopic or open? Arthroscopic fixation is preferred whenever feasible — minimally invasive, with direct visualisation of the articular surface for precise reduction and good access to the common lateral medial condyle site. An open medial or lateral parapatellar approach is reserved for very large lesions (greater than 3 square cm), far posterior lesions, lesions needing bone grafting, or when a perpendicular arthroscopic screw trajectory is impossible.
- Arthroscopic fixation
- Less than 2-3 square cm
- Open fixation
- Greater than 3 square cm or posterior lesions
- Arthroscopic fixation
- 2-3 portal incisions
- Open fixation
- Medial parapatellar or limited arthrotomy
- Arthroscopic fixation
- Arthroscopic, direct
- Open fixation
- Direct open visualisation
- Arthroscopic fixation
- Moderate
- Open fixation
- Higher
- Arthroscopic fixation
- Lower
- Open fixation
- Higher
- Arthroscopic fixation
- Limited (augmented techniques)
- Open fixation
- Full access to bed
- Arthroscopic fixation
- Good (fluoroscopic guidance)
- Open fixation
- Excellent (direct visual)
- Arthroscopic fixation
- 4-6 months
- Open fixation
- 6-9 months
Consent specifically for fragment fragmentation or failure of fixation, nonunion requiring revision surgery, hardware irritation needing a second arthroscopy for removal, infection (less than 1%), stiffness and arthrofibrosis, progression to osteoarthritis, and the possibility that salvage procedures (OATS, ACI or allograft) may be needed if fixation fails.
The Operation
The goal is to expose the lesion, confirm instability by probing, debride the bed to bleeding bone, reduce the native fragment anatomically, and fix it with rigid countersunk devices while protecting the physis in children and the neurovascular structures throughout. The exposure — arthroscopic portals or a mini-arthrotomy — is laid out as the first operative steps below.
Operative sequence
- Supine on a radiolucent table, with a lateral post at thigh level or a leg holder; proximal thigh tourniquet inflated to 250 mmHg after exsanguination.
- Drape the leg free to allow full movement from full extension to at least 120 degrees of flexion.
- Fluoroscopy (C-arm) is mandatory — obtain AP, lateral and notch views to confirm lesion position and size before draping; it guides screw trajectory and length and verifies fixation afterwards.
- Equipment: 30-degree and 70-degree arthroscopes; a headless compression screw set (Herbert, Acutrak or MMP, 2.0-4.5 mm); a bioabsorbable pin set (PLLA or PGA, 1.5-2.7 mm); and 1.2-2.0 mm K-wires.
- For most lesions establish standard portals: the anterolateral portal as the primary viewing portal for a lateral medial condyle lesion, and the anteromedial portal as the instrument portal.
- Add a superomedial or accessory medial portal when needed to place screws perpendicular to the fragment surface; a posteromedial portal is occasionally required for far posterior medial condyle lesions that cannot be reached from the anterior portals.
- For an open approach (lesion greater than 3 square cm, far posterior, needing bone graft, or where a perpendicular arthroscopic trajectory is impossible), use a medial parapatellar mini-arthrotomy for medial condyle lesions and a lateral parapatellar arthrotomy for lateral condyle lesions, displacing the patella to inspect the lesion directly.
- Structures at risk: the saphenous nerve and its infrapatellar branch during medial portal placement and the medial parapatellar approach (identify and protect); the common peroneal nerve posterolaterally during posterolateral portal placement; and the popliteal vessels deep posteriorly — avoid posterior capsule penetration when drilling or fixing far posterior lesions.
- Perform a systematic diagnostic arthroscopy of all compartments; document lesion size, location, cartilage integrity, stability on probing and any loose bodies.
- Probe the fragment before committing to fixation: insert the probe at the fragment edge and apply gentle lifting pressure. A rock-solid fragment that does not budge — especially in a juvenile — should prompt reassessment of whether surgery is needed at all.
- Grade the lesion (Dipaola): grade I intact cartilage, stable, in situ; grade II cartilage breached, partially detached but hinged in situ (fixation); grade III cartilage fully breached, completely detached but sitting in the crater (fixation); grade IV empty crater with the fragment displaced as a loose body (retrieve and fix, or salvage).
- If the fragment is hinged or detached but viable (intact cartilage with attached subchondral bone), prepare it for fixation: clear loose fibrous tissue from its deep surface and from the crater bed with a curette and shaver.
- Debride the crater bed back to bleeding cancellous bone — essential for healing. Remove all sclerotic bone from the base.
- Do NOT over-resect the subchondral bone plate, or the fragment will sink and the articular surface will be incongruent.
- Reduce the fragment into its anatomical position with a grasper; if it is hinged, fold it back into position from its hinge point.
- Confirm anatomical reduction from multiple angles — the fragment cartilage must be perfectly flush with the surrounding surface, with no step-off.
- A probe run across the surface should glide smoothly. A small amount of bleeding from the crater margins confirms a viable bed.
- Insert 1.2-1.6 mm K-wires percutaneously under fluoroscopic guidance to hold the reduction; place at least two from different angles to prevent fragment rotation during definitive fixation.
- Confirm reduction with fluoroscopy (AP, lateral and notch views) and direct arthroscopic vision before any definitive device is placed.
- Select screw size by fragment size: 2.0-2.4 mm for small fragments (less than 1.5 square cm), 3.0-4.0 mm for medium (1.5-3 square cm), and 4.5 mm for large (greater than 3 square cm).
- Choose an entry point and trajectory that places the screw perpendicular to the fragment surface; drill a guide pin over the K-wire with a cannulated system under fluoroscopy and measure length so the threads engage the fragment and anchor into subchondral bone beyond the lesion.
- Insert the headless compression screw (Herbert, Acutrak or MMP), countersinking the trailing thread fully beneath the cortex; confirm it is buried below the articular cartilage by direct vision and fluoroscopy.
- Typically 2-3 screws for a medium lesion, spaced to distribute compression across the fragment.
- Use bioabsorbable pins (PLLA or PGA) when the fragment is too small or thin for a screw, when the bone is osteoporotic and will not hold threads, or when avoiding hardware across an open physis is critical in a juvenile.
- Drill 1.5-2.0 mm channels through the fragment into subchondral bone, insert the pins via the delivery cannula, and tap the heads flush beneath the articular surface with a plastic impactor.
- Typically 3-5 pins are placed. Bioabsorbable devices resorb over 12-36 months (PLLA more slowly than PGA), avoiding a hardware-removal procedure but giving less rigid fixation than metal.
- After fixation, drill 1-2 mm K-wires through the reduced fragment into the bleeding cancellous bed; place 4-8 holes targeting the fragment-bed interface to stimulate fibrovascular ingrowth and bony healing.
- For stable in-situ lesions treated without displacement, retrograde drilling from the condylar cortex through the subchondral bone (away from the articular surface) may be performed without breaching the cartilage.
- In open fixation, pack morsellised cancellous autograft (from the distal femur or proximal tibia) into any cavity between the fragment and the bed before final screw compression — straightforward through the arthrotomy.
- Arthroscopic bone grafting of the bed is possible but limited, which is a driver for choosing an open approach when significant bone loss is present.
- Final arthroscopic check: anatomical reduction (no step-off or gap), all hardware fully countersunk below the cartilage, stable fixation (no movement on probe pressure), no loose bodies, and a smooth range of motion with no catching or impingement on flexion and extension.
- Withdraw the instruments, close portal incisions with 4-0 nylon, and apply a sterile compression dressing with a hinged knee brace locked in extension.
- Over-resecting the subchondral bone plate — the fragment sinks into a crater that is too deep, creating an incongruent articular surface and accelerating degeneration.
- Destroying the fragment's articular cartilage during debridement — handle the fragment carefully with graspers, never with a shaver near the cartilage surface.
- Removing too much bone from the bed, leaving a crater the fragment cannot fill — measure carefully.
- Leaving fibrous tissue at the interface — residual fibrous tissue prevents bone-to-bone healing.
- Proud hardware is the commonest and most dangerous error — any screw head or thread above the articular surface shreds the opposing tibial cartilage; countersink fully and confirm with probe and fluoroscopy.
- Fragment comminution — over-tightening fractures a small or osteoporotic fragment; use gentle compression and bioabsorbable pins if the bone is fragile.
- Screw crossing the physis in a juvenile — check the fluoroscopic trajectory against the physis; use bioabsorbable devices or keep screws within the epiphysis.
- Screw too long — posterior penetration beyond the femoral cortex can injure the popliteal neurovascular bundle; check depth on lateral fluoroscopy.
- Inadequate compression — loose fixation leads to nonunion; ensure the threads engage both the fragment and the bed.
Always probe the fragment first. Insert the probe at the fragment edge and lift gently — a fragment that will not budge, especially in a juvenile, should make you question whether surgery is needed. Look for a hinge point where the fragment is still attached as a reference for anatomical reduction, and mark the fragment and crater edges with radiofrequency ablation or a small curette to sharpen visualisation during reduction.
Reduce the fragment, hold it with a grasper, and inspect the surface from the viewing portal — look for any gap between fragment and surrounding cartilage. A probe run across the surface should glide with no step-off. Only then place temporary K-wires from different angles to hold the reduction while you set the definitive fixation.
Aim for perpendicular screw placement to the fragment surface to maximise compression and avoid shear. Enter from the non-articular cortex of the femoral condyle, drive the screw through the fragment into the subchondral bed, and countersink every screw fully beneath the articular cartilage. Run a probe over the fixation site at full visualisation — even 1 mm of proud hardware will damage the opposing tibial cartilage in flexion.
Aftercare & Complications
Rehabilitation | Phase | Timing | Weight-bearing and bracing | Therapy and milestones | |-------|--------|----------------------------|------------------------| | 1 | 0-6 weeks | Hinged brace locked in extension for ambulation (unlock for ROM); toe-touch (15-20%) for 2 weeks, 50% partial at 2-4 weeks, full by 6 weeks | Gentle passive flexion to 90 degrees within 2 weeks, full flexion by 6 weeks, full extension from day 1; active-assisted and passive only for 4 weeks; cryotherapy; optional CPM 0-90 degrees | | 2 | 6-12 weeks | Full weight-bearing without brace (extend protected weight-bearing to 8-12 weeks for bioabsorbable fixation) | Closed-chain mini-squats (0-45 degrees), leg press, stationary cycling; pool rehab; no open-chain work until 12 weeks (shear); no running, jumping or pivoting | | 3 | 4-9 months | Return to sport guided by symptoms and MRI healing | Straight-line running from 4 months if asymptomatic and MRI shows healing; sport-specific drills from 5-6 months; full return to competitive sport at 6-9 months | Juvenile patients may progress faster (return to sport at 4-6 months) when healing is confirmed on MRI and the physis is still open; adults generally require 6-9 months before full return to impact sports. Follow-up imaging - 6-week radiographs: check screw position, fragment reduction and early signs of healing.
- 3-month radiographs and MRI: assess bony healing across the fragment-bed interface; a persistent gap or fluid signal suggests nonunion.
- 6-month MRI: confirm complete healing before clearing return to sport.
- 12-month radiographs and MRI: final healing assessment; consider hardware removal if metal screws are symptomatic or prominent. Salvage when fixation fails or the fragment is unsalvageable If the fragment is necrotic, fragmented or too small, or if fixation has failed, treatment shifts from fixation to salvage — chosen by lesion size and patient age. Microfracture suits small lesions (less than 2-3 square cm) but produces fibrocartilage durable for only about 5-7 years, so it is a poor lifetime solution in the very young. OATS, ACI and allograft provide hyaline or hyaline-like cartilage for larger defects.
- Best lesion size
- Less than 2-3 square cm
- Cartilage type
- Fibrocartilage
- Key limitations
- Durable 5-7 years; less durable than hyaline; unsuitable for large lesions
- Best lesion size
- 1-4 square cm
- Cartilage type
- Hyaline cartilage (autograft)
- Key limitations
- Donor-site morbidity; limited graft area; plug mismatch at edges
- Best lesion size
- 2-10 square cm
- Cartilage type
- Hyaline-like cartilage
- Key limitations
- Two-stage procedure; 12-18 month rehab; expensive; graft hypertrophy risk
- Best lesion size
- Greater than 4 square cm
- Cartilage type
- Hyaline cartilage (allograft)
- Key limitations
- Limited donor availability; disease-transmission risk; late graft failure
Complications
- Incidence
- 5-15%
- Recognition
- Persistent pain 6 months after fixation; MRI shows no bony healing across the interface; fragment remains mobile on probing
- Prevention and management
- Prevention: bed to bleeding bone, rigid compression, subchondral drilling, protected weight-bearing for 6-8 weeks. Management: revision fixation with bone grafting if viable; salvage to OATS, ACI or allograft if persistent
- Incidence
- 5-10%
- Recognition
- Breakup of the fixed fragment; loss of articular surface congruence; mechanical symptoms; loose body formation
- Prevention and management
- Prevention: avoid over-compression; use bioabsorbable pins for thin or fragile fragments. Management: debride and salvage — microfracture, OATS or allograft for the resulting defect
- Incidence
- 2-10%
- Recognition
- Catching, locking or pain on flexion; arthroscopy shows a proud screw or pin; chondral damage on the opposing tibial plateau
- Prevention and management
- Prevention: countersink all hardware fully; confirm with probe and fluoroscopy before closure; use headless screws. Management: arthroscopic hardware removal with chondroplasty of the damaged surface
- Incidence
- Less than 5% (juvenile only)
- Recognition
- Limb-length discrepancy or angular deformity developing after fixation; scanogram shows premature fusion of the distal femoral physis
- Prevention and management
- Prevention: bioabsorbable devices or metal screws within the epiphysis parallel to (not crossing) the physis; monitor with serial radiographs. Management: physeal bridge resection if detected early; guided growth for angular correction
- Incidence
- 5-10%
- Recognition
- Loss of flexion greater than 10 degrees or extension lag greater than 5 degrees at 6-8 weeks; pain on forced flexion
- Prevention and management
- Prevention: early gentle ROM within the first 2 weeks; avoid prolonged immobilisation; hinged brace allows controlled motion. Management: structured physiotherapy; manipulation under anaesthesia beyond 8 weeks; arthroscopic arthrolysis if refractory
- Incidence
- 15-30% (long term)
- Recognition
- Progressive joint-space narrowing on radiographs years after fixation; increasing pain and stiffness; crepitus
- Prevention and management
- Prevention: anatomical reduction and rigid fixation; early treatment before displacement and cartilage loss. Management: activity modification and analgesia; realignment osteotomy if malalignment contributes; arthroplasty for end-stage change
- Incidence
- Less than 1%
- Recognition
- Erythema, warmth, swelling, pain out of proportion to the expected course; fever; raised inflammatory markers
- Prevention and management
- Prevention: sterile technique; single-dose cefazolin at induction. Management: urgent arthroscopic washout, culture-directed antibiotics, hardware removal if infection persists
Viva & Exam Focus
STABLESTABLE — OCD lesion stability assessment
FIXATEFIXATE — OCD fixation principles
The trap: treating all OCD as adult OCD — operating too early on a stable juvenile lesion, or using rigid implants that cross an open physis and risk premature physeal closure. The fix: confirm skeletal maturity with a full-leg radiograph (physes) and a hand radiograph for bone age. A stable juvenile lesion gets protected weight-bearing and activity modification for 3-6 months before surgery is considered. If fixation is needed in a juvenile, use bioabsorbable devices that do not cross the physis, or place screws entirely within the epiphysis.
The trap: discarding a displaced fragment and proceeding straight to microfracture in a young patient — the native fragment, if viable, provides hyaline cartilage superior to fibrocartilage. The fix: always assess the fragment at arthroscopy. A viable fragment has intact subchondral bone attached to the articular cartilage. If it is in situ or hinged but viable, fix it. Reserve marrow stimulation for fragments that are fragmented, necrotic or unsalvageable. In patients under 25 with a viable fragment, fixation should always be attempted before salvage.
The trap: leaving headless compression screws proud to the articular surface, causing chondral damage, catching and early osteoarthritis — even 1 mm of proud hardware shreds the opposing tibial cartilage in flexion. The fix: use headless screws (Herbert, Acutrak, MMP) countersunk fully beneath the surface; confirm burial by direct vision and fluoroscopy; run a probe over the site to ensure nothing is proud. If the bone is too soft to hold a countersunk screw, use bioabsorbable pins.
The trap: relying on MRI alone to plan surgery — MRI sensitivity for instability is about 75-85%, so some unstable lesions appear stable. The fix: diagnostic arthroscopy with probe testing is the definitive assessment. An unstable fragment lifts from the bed with probe pressure, has a fluid-filled interface, and may have a hinge of attached cartilage. Plan fixation for unstable lesions and observe stable ones non-operatively.
The trap: placing metal compression screws across an open physis, risking premature physeal arrest, limb-length discrepancy or angular deformity in a growing child. The fix: in juveniles, direct screws within the epiphysis parallel to — not crossing — the physis, or use bioabsorbable pins (PLLA, PGA) placed entirely within the epiphyseal segment. If a large lesion demands a crossing trajectory, use bioabsorbable devices that resorb without permanent physeal tethering and monitor with serial radiographs.
The trap: fixing a small, stable, healed lesion in a skeletally immature patient who would have healed with protected loading alone — fixation adds hardware complications, arthrofibrosis and infection risk. The fix: the algorithm runs on two axes — skeletal maturity and stability. Stable juvenile: non-operative. Unstable juvenile: fixation. Unstable adult: fixation or salvage. Stable adult: activity modification and monitoring, with surgery only if it destabilises. Do not operate without a clear instability indication.
Clinical Decision Scenarios
Practise clinical reasoning and management decisions out loud
“A 13-year-old male footballer presents with 6 weeks of activity-related right knee pain. MRI shows a 15 mm OCD lesion on the lateral aspect of the medial femoral condyle with an intact articular cartilage surface and a thin T2 high-signal line at the fragment-bone interface. His physes are open. How do you manage him?”
“A 17-year-old female gymnast with closed physes presents after an acute twisting injury. MRI shows a 20 mm OCD lesion on the lateral medial femoral condyle with a displaced osteochondral fragment sitting in the intercondylar notch. The articular cartilage on the fragment appears intact. Talk me through your management.”
“You are asked to see a 22-year-old man with a 3-year history of medial knee pain. Previous MRI showed a 25 mm OCD lesion on the lateral medial femoral condyle. He was managed non-operatively and his symptoms persisted. Repeat MRI now shows an empty crater on the medial condyle with no identifiable loose body and full-thickness cartilage loss. How do you proceed?”
Definition and epidemiology
- OCD equals separation of a subchondral osteochondral fragment, most commonly on the lateral aspect of the medial femoral condyle (60-70%)
- Juvenile OCD (open physes) versus adult OCD (closed physes) — skeletal maturity is the single most important prognostic factor
- Bilateral in 20-30% — always image the contralateral knee
- More common in adolescents and young adults; male predominance; association with sports and repetitive loading
- Aetiology uncertain: repetitive trauma, vascular insufficiency to the subchondral bone, and genetic predisposition
Classification
- Dipaola: grade I intact and stable; II partially detached hinge; III detached in crater; IV displaced loose body with empty crater
- MRI instability signs: high T2 signal line at the interface, fluid rim, cartilage breach, cyst greater than 5 mm beneath the fragment
- Arthroscopic probing is the gold standard for stability — probe lifts unstable fragments from the bed
Treatment algorithm
- Stable juvenile OCD: non-operative — protected weight-bearing, activity restriction, serial MRI every 3-4 months; 50-60% heal
- Unstable juvenile OCD: arthroscopic fixation with bioabsorbable pins or physeal-sparing screws
- Unstable adult OCD: arthroscopic or open fixation with headless compression screws
- Unsalvageable fragment: microfracture (less than 2-3 square cm), OATS (1-4 square cm), ACI (2-10 square cm), allograft (greater than 4 square cm)
- Failed fixation: revision fixation with bone grafting if viable; salvage procedures if not
Fixation devices
- Headless compression screws (Herbert, Acutrak, MMP): most rigid; 2.0-4.5 mm; must be countersunk fully beneath the articular surface
- Bioabsorbable pins (PLLA, PGA): avoid hardware-removal surgery; preferred in juveniles to protect the physis; less rigid than metal
- Metal screws in juveniles: must stay within the epiphysis, not cross the physis — risk of premature physeal closure
- Typically 2-3 screws or 3-5 bioabsorbable pins depending on fragment size
Operative technique — key steps
- 1. Diagnostic arthroscopy with probe stability testing — classify the lesion
- 2. Debride the fragment bed to bleeding cancellous bone — remove all fibrous tissue
- 3. Anatomical fragment reduction — no step-off greater than 1 mm acceptable
- 4. Temporary K-wire fixation (2 K-wires at different angles)
- 5. Definitive fixation: headless compression screws or bioabsorbable pins, countersunk fully beneath the articular surface
- 6. Subchondral drilling through the fixed fragment for vascular channels
- 7. Final arthroscopic confirmation: anatomical reduction, no proud hardware, no fragment motion on probing
- 8. Hinged knee brace and protected weight-bearing protocol
Complications
- Nonunion (5-15%): bed debridement, rigid fixation, drilling, protected weight-bearing; revision or salvage if persistent
- Fragment fragmentation (5-10%): avoid over-compression; salvage to microfracture or OATS if it occurs
- Hardware prominence (2-10%): countersink all hardware, confirm with probe; arthroscopic removal if symptomatic
- Physeal closure (less than 5%, juvenile only): bioabsorbable devices or epiphyseal-only screw placement
- Arthrofibrosis (5-10%): early ROM; MUA or arthroscopic arthrolysis if refractory
- Long-term osteoarthritis (15-30%): best prevented by anatomical reduction and early treatment
Rehabilitation milestones
- Weeks 0-2: toe-touch weight-bearing, hinged brace, passive ROM 0-90 degrees
- Weeks 2-4: 50% partial weight-bearing, progressive ROM
- Weeks 4-6: full weight-bearing, closed-chain strengthening
- Months 4-6: straight-line running if MRI shows healing
- Months 6-9: sport-specific drills, full return to competitive sport
- Metal screws: consider removal at 6-12 months if symptomatic or preferred
Background & Evidence
Epidemiology. Osteochondritis dissecans is separation of a subchondral osteochondral fragment from the surrounding bone. It is most common in adolescents and young adults, with a male predominance and an association with sports and repetitive loading, and it is bilateral in 20-30% of cases (so always image the contralateral knee). The aetiology is uncertain; leading theories are repetitive microtrauma, vascular insufficiency to the subchondral bone, and genetic predisposition. The classical site is the lateral aspect of the medial femoral condyle (60-70% of cases), but the lateral femoral condyle, patella and trochlea are all recognised.
- Frequency
- 60-70% (most common)
- Surgical access considerations
- Anterolateral viewing portal with anteromedial instrument portal; visible at 60-90 degrees of flexion
- Frequency
- 15-20%
- Surgical access considerations
- Anteromedial instrument portal with anterolateral viewing
- Frequency
- 5-10%
- Surgical access considerations
- Superolateral and superomedial patellar portals
- Frequency
- 5-10%
- Surgical access considerations
- Standard portals with knee flexion and probe manipulation
- Frequency
- 20-30% of cases
- Surgical access considerations
- Examine the entire joint; image the contralateral knee
Classification. Stability is graded arthroscopically by the Dipaola system, and supplemented preoperatively by MRI instability signs. Note that MRI sensitivity for instability is about 75-85% — arthroscopic probing remains the definitive test.
- Arthroscopic findings
- Intact articular cartilage, stable on probing, fragment in situ
- Management
- Non-operative (especially in juveniles)
- Arthroscopic findings
- Cartilage partially breached, fragment partially detached but hinged in situ
- Management
- Fixation
- Arthroscopic findings
- Cartilage fully breached, fragment completely detached but sitting in the crater
- Management
- Fixation
- Arthroscopic findings
- Empty crater with the fragment displaced as a loose body
- Management
- Retrieve and fix, or salvage
Key evidence. Skeletal maturity is the single most important prognostic factor. Juvenile OCD (open physes) heals in 50-60% of cases with protected weight-bearing and activity modification over 3-6 months, whereas adult OCD (closed physes) heals in only about 20-30% with non-operative care. Once fixation is indicated, the choice between metal and bioabsorbable devices does not change the outcome: Perelli et al. (2019) found good long-term healing with both and no difference between device types, so selection is guided by fragment size, bone quality and physeal status rather than by fixation material. In juveniles, bioabsorbable pins avoid a second procedure for hardware removal (Adachi 2015; Komnos 2021), while in adults metal headless compression screws give reliable rigid fixation (Barrett 2016). The overall message — preserve and fix the native fragment when it is viable, and choose the device by fragment and physis rather than by material — is a consistent viva theme.
References
Management of osteochondritis dissecans of the knee: current concepts review
- Comprehensive review of OCD natural history, classification, and treatment algorithms for both juvenile and adult presentations
- Skeletal maturity is the single most important prognostic factor — juvenile OCD heals significantly better than adult OCD with non-operative or surgical treatment
- Evidence-based treatment algorithm: stable juvenile lesion equals non-operative; unstable juvenile lesion equals arthroscopic fixation with physeal-sparing technique; unstable adult lesion equals fixation or salvage
Internal fixation of juvenile osteochondritis dissecans lesions of the knee
- Case series of juvenile OCD lesions treated with bioabsorbable fixation, demonstrating high healing rates in skeletally immature patients
- Internal fixation with physeal-sparing technique produced reliable fragment healing and return to sport in the majority of juvenile patients
- Bioabsorbable devices avoided the need for hardware removal surgery, which is particularly important in growing children with open physes
Internal Fixation of Osteochondritis Dissecans of the Knee Leads to Good Long-Term Outcomes and High Degree of Healing without Differences between Fixation Devices
- Long-term follow-up study comparing metal screws and bioabsorbable devices for OCD fixation — both fixation types achieved good outcomes with high healing rates
- No significant difference in healing or functional outcomes between metal and bioabsorbable fixation devices at long-term follow-up
- Device selection should be guided by fragment characteristics, bone quality, and skeletal maturity rather than fixation type alone
Functional and radiographic outcomes of unstable juvenile osteochondritis dissecans of the knee treated with lesion fixation using bioabsorbable pins
- Case series evaluating bioabsorbable pin fixation for unstable juvenile OCD — high healing rate and good functional outcomes at follow-up
- Bioabsorbable pins eliminated the need for a second procedure for hardware removal in all patients
- Slight limitation noted for in-situ stable lesions where fixation may be unnecessary — emphasises the importance of instability assessment before surgery
Internal Fixation of Unstable Osteochondritis Dissecans in the Skeletally Mature Knee with Metal Screws
- Case series of adult OCD (closed physes) treated with metal screw fixation — high rate of fragment healing and good functional outcomes
- Metal headless compression screws provided rigid fixation allowing early rehabilitation and reliable fragment union
- Some patients required hardware removal due to prominence, supporting the consideration of bioabsorbable alternatives in select cases
Juvenile Osteochondritis Dissecans of the Knee Joint: Midterm Clinical and MRI Outcomes of Arthroscopic Retrograde Drilling and Internal Fixation with Bioabsorbable Pins
- Midterm follow-up of arthroscopic retrograde drilling combined with bioabsorbable pin fixation for juvenile OCD — good clinical and MRI healing outcomes
- Arthroscopic retrograde drilling preserved the articular cartilage surface while creating vascular channels for healing
- Bioabsorbable pin fixation was effective for stabilising fragments while avoiding physeal injury and hardware removal in growing children