Meniscal Detachment


This term can be used to describe a high energy injury to the meniscus, usually in young patients. During the act of ligament rupture there is very rapid dissipation of energy with instantaneous displacement of the femur on the tibia "snap":-



This can cause severe damage to the meniscii either wrenching them from their attachment ("peripheral detachment") or by splitting off a large "bucket handle" segment. This is different to the common degenerative tear where a meniscus has gradually become weaker and weaker to finally fail following a trivial injury ("the straw that broke the Camel's back").


  

  Bucket Handle Tear                Normal


In young patients these injuries can be repaired reducing the risk of early osteoarthritis. It is important that they are recognised early to increase the success rate for repair. Meniscal detachment can accompany any pattern of ligament rupture :-


Ligament Injury

Rate of Meniscal detachment

MCL

??

ACL

  • 36% Medial Tear
  • 47% Lateral Tear

PCL

??

PLC

??

Multiligament injury

  • 2.7 % Medial Posterior Root Avulsion


Diagnosis



Hx

  • Significant force
  • Significant twisting injury
  • Immediate pain +- "pop"
  • Immediate swelling with haemarthrosis

LOOK

FEEL

  • Joint line tenderness
  • Associate ligament injury causing localised tenderness

MOVE

  • Reduced active movement due to pain
  • True locked knee: Passive flexion deformity, the knee will flex reasonably normally but cannot be straightened out.


Exclude combined MCL + Meniscus


Exclude combined ACL + Meniscus

XRAYS

AP and Lateral views

  • Usually normal


Exclude combination injuries

  • ACL: Segond fracture, Tibial spine avulsion
  • MCL: Medial opening

MRI

This is the principle reason for MRI scans in ACL rupture - not to confirm the ACL rupture which is usually clinically obvious


Emergency Room treatment


Treatment is usually dictated by the ligamentous injury. For an isolated "bucket handle tear" with a true locked knee:-



Specialist treatment


Meniscal detachments are amendable to repair with sutures if seen early. Once the femur has rolled over the meniscal fragment for a week or two it is too distorted to fix back in position. Additionally the longer this injury is left the poorer the healing capacity when the two parts are reunited.


 


The blood supply to the meniscus is normally poor (hence degeneration with age) and failure of meniscal healing leads to failure of meniscal suturing in 10-30 percent of cases. Even with this relatively high rate of failure repair is recommended because the long term benefit for the successful cases is high, and the morbidity from a second arthroscopy and resection of the failed meniscal repairs is low.


Rehabilitation


As an isolated treatment meniscal repair should be protected from shear forces for 8 weeks. This means avoiding flexion beyond 100 degrees and excessive load bearing under flexion. Braces can be used for patients who find it difficult to comply.


When repaired as part of a ligament reconstruction the meniscus can usually be ignored as patients tend to protect the knee for the first 6-8 weeks and the risk of disrupting the meniscal repair is low.

Mr Gavin Holt :: CotswoldClinics.com :: Print this frame