Meniscal Knee Injuries

Written by: Dr Jeremy Steinberg; additional contribution by: Dr Amanda Cormack – created: 17 June 2020; last modified: 15 March 2023

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Meniscal Knee Injuries

The conventional belief has been that patients presenting with clicking, catching, or locking symptoms are more likely to have a meniscal tear and that arthroscopic partial meniscectomy (APM) would yield favorable outcomes. However, current evidence does not support this traditional view. Concerns have been raised about the drift from evidence-based indications, moving from treating permanently locked knees to those with less severe mechanical symptoms.

Clinical Features

Mechanical symptoms have been proven to not be associated with the presence of meniscal tear. One systematic review found sensitivity of 0.32 - 0.69 and specificity of 0.45 - 0.74.for meniscal tear, i.e. both crossing 0.5 which is a likelihood ratio of 1.0.

There may be other explanations for mechanical symptoms. These can include patellofemoral joint giving way, which is transient and related to fatigue or overload of the quadriceps, locking or malalignment of the patella due to Q angle stiffness, loose bodies or chondral lesions causing mechanical symptoms, and ultimately, mechanical symptoms may be multifactorial in their causes.

Degenerative tears are generally not unstable and they usually don't sublux into the joint. This means they shouldn't cause "mechanical symptoms"

Treatment

There has been continuous misuse and misapplication of trial data

• Non-inferiority does not justify arthroscopy. We should expect operations to provide clinically important benefits and not merely be "non-inferior" to non-surgical treatments
• Misuse of study conclusions
• Ignoring long term follow up data
• Using cross-over percentages from non-surgical group to APM to justify surgery
• Ignoring the results of negative trials
• Ignoring the evidence that surgeons cannot predict who will benefit from APM
• Ignoring the evidence that APM may be worse than nothing with physical (increased OA) and financial harm

Conceptually the idea of going for a potentially harmful treatment that has been proven not to work because a non-operative treatment didn't work does not make logical sense.

Non-Operative Management

This is the "masterly neglect" with the aim of meniscal repair and/or knee adaptation. The greatest healing potential are those that are short (<1cm), longitudinal, stable, and asymptomatic. Stability can be evaluated arthroscopically with probing. In high level athletes there is high risk of tear progression, becoming symptomatic, and eventually requiring APM.

Operative Mx

Three broad types of surgery

1. Preservation: Long recovery but reduce risk of OA
2. Removal of damaged tissue: Speedy recovery but risk future OA
3. Replacement of damaged tissue

Meniscus Zones

Three zones in the meniscus, with reducing blood supply the more centrally located the tissue

1. Red-red zone
2. Red-white zone
3. White-white zone

Meniscal Repair

• Tear selection for repair
  • Ideal = Unstable, vertical-longitudinal tear in periphery
  • Meniscus zones: Only peripheral 10-25% of the meniscus is vascularised
  • However acceptable healing rates can occur in the other zones
  • Also beneficial: tear <12 weeks, younger patients, combined ACL repair
• Bucket handle = vertical longitudinal peripheral tear. The classical teaching is that completely locked knees should be repaired urgently to prevent long term motion loss
• Techniques
  • Inside-out (gold standard) or outside-in
  • Newer fixation devices (all inside)
  • All forms of repair require many months of prolonged rehabilitation
• Postoperative rehab
  • typically includes restrictions in knee flexion RO and weight bearing for 6 weeks.
  • Low impact exercise but no running for 2-3 months
  • Return to competition in 6-8 months

Partial Meniscectomy Classic Criteria

The traditional indication is where masterly neglect or repair have a low chance of success. The following are some typical criteria used in guidelines. However they are not evidence based:

• complex tear patterns
• chronic displaced tears with plastic deformation
• tears in white-white region (rim width > 8mm)
• Failed repair
• Degenerative tears (despite being a disproven treatment)

Contrary to received wisdom, mechanical symptoms do not confer better outcomes from APM and there is more long term OA

In middle aged and older patients having APM there is higher risk of accelerated osteoarthritic changes and the risk of TKJR is higher.

Meniscus Replacement

• Allografts
• Synthetic scaffolds
• Does not allow return to competitive sport

Degenerative Tears

Meniscal surgery is not indicated in the context of degenerative tears. This was evaluated in an RCT by Sihvonen et al

• 146 patients with degenerative meniscal tears without OA. Included those with locking symptoms.
• Partial meniscectomy vs sham surgery
• No difference from 12 months to 5 years follow up.
• Considered one of the highest quality RCTs that exist in all of the surgical literature, and one of the only placebo controlled trials in the entire orthopaedic surgery literature.

Even experienced orthopaedic surgeons cannot predict who will benefit from surgery for degenerative meniscal tears. If conservative management fails, the default isn’t to do something (surgery) that has been disproven to work (and can even make it worse with OA)

There is increased joint space narrowing after arthroscopic partial meniscectomy compared to patients managed non-surgically.

Literature Review

Literature Review

Reviews from the last 7 years: review articles, free review articles, systematic reviews, meta-analyses, NCBI Bookshelf

Articles from all years: PubMed search, Google Scholar search.

TRIP Database: clinical publications about evidence-based medicine.

Other Wikis: Radiopaedia, Wikipedia Search, Wikipedia I Feel Lucky, Orthobullets,