Apparent spontaneous healing of complete ACL tear

Case contributed by Dr Chris O'Donnell

Presentation

Acute injury whilst rollerblading with instablity and pain. No active treatment. Now knee feels unstable ? extent of ACL injury

Patient Data

Age: 60
Gender: Female
MRI

Initial MRI scan following acute injury (fall while rollerblading)

Complete disruption to the anterior cruciate at its femoral attachment (arrow). The posterior cruciate remains intact.

On the medial side there is a large horizontal cleavage tear involving the meniscus extending predominantly into the posterior horn. Articular cartilage is preserved. There is partial disruption to the medial collateral ligament posteriorly at its femoral attachment.

On the lateral side meniscus and articular cartilage are normal. There is, however, a definite crack fracture involving the lateral femoral condyle. No deformity. Lateral collateral ligament and posterolateral corner structures are normal including popliteus.

Minor chondromalacia involves the apex of the patellar facet. Moderate joint effusion. Small Baker cyst.

Conclusion:

This patient has had a substantial valgus force injury with complete disruption to the anterior cruciate ligament, marked horizontal cleavage tearing of the medial meniscus, possibly minor disruption to the medial collateral ligament and an undisplaced crack fracture involving the lateral femoral condyle together with minor bone bruising on the posterior aspect of the lateral tibial plateau.

MRI

Follow-up scan 5 years later

There is a persistent horizontal cleavage tear involving the body and posterior horn of the medial meniscus. Associated minimal parameniscal cyst formation. Medial collateral ligament is intact.

Thinning of articular cartilage overlying the medial femoral condyle. There is actually a small flap-type tear. Minimal reactive bone marrow oedema.

The anterior is now in continuity. Laterally the meniscus and articular cartilage are relatively normal. The lateral collateral ligament and posterolateral corner structures are normal including popliteus. Minimal chondromalacia at the apex of the patellar facet. No obvious intra-articular loose body. No recent bone injury.

Conclusion:

Previously noted complete ACL tear appears to have healed in continuity.

Small flap-type tear involving articular cartilage overlying the central weight bearing portion of the medial femoral condyle associated with a horizontal cleavage tear involving the body and posterior horn of the medial meniscus together with a small medially projecting meniscal cyst.

No other signs of substantial internal joint derangement apart from the apex of the patellar facets where there is minor chondromalacia.

Case Discussion

Although uncommon it is recognized that in some patients the ACL will spontaneously heal with return of function.

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Case information

rID: 49672
Case created: 29th Nov 2016
Last edited: 30th Nov 2016
Inclusion in quiz mode: Excluded

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