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Hip and knee surgery: Cartilage resurfacing - the last frontier

Mr Fares Haddad and Mr Kyriacos Eleftheriou consider recent advances in treating cartilage problems

Mr Fares Haddad and Mr Kyriacos Eleftheriou consider recent advances in treating cartilage problems

Case history A 38-year-old fitness instructor has been investigated for persistent right knee pain that has been limiting his lifestyle and work over the last nine months or so. He has already tried intensive physiotherapy and a period of NSAIDs but his symptoms are continuing. Clinical examination is generally unremarkable and there is no ligamentous or meniscal injury.

Plain radiographs are also normal, but a MRI scan followed by arthroscopy confirms a 3cm2 full thickness cartilage defect of the medial femoral condyle. The patient has been looking on the internet and found out about procedures to repair his defect, and so is keen to have something done to get back to work and sport.

Diagnosis and management

Cartilage defects are a major cause of knee joint disease and symptoms; they seldom heal spontaneously, and they lead to later osteoarthritis. Although in a number of individuals these can be managed conservatively, many continue to complain of severe lifestyle limiting symptoms.

Joint replacement and metal resurfacing is disproportionate to the problem in most cases, but is also inappropriate for the majority of such patients who tend to be young and active. This has led to the development of new techniques to help such patients.

'Older' new techniques

Procedures include abrasion arthroplasty, subchondral drilling and microfracture. They were initially coined 'marrow stimulation procedures'. They:

  • restore articular surface, give good, pain-free range of movement and reduce further cartilage damage
  • place subchondral mesenchymal cells into contact with the defect ­ a healing response
  • may not be effective in over-40s ­ healing ability impaired with age
  • induce fibrocartilage production (type I collagen) ­ inferior to normal type II collagen articular cartilage
  • are low-cost procedures with low morbidity.

Microfracture appears to have best results (pain relief of up to 75 per cent of young active patients at three-five years) but is less successful in non-femoral condyle defects and defects bigger than 2cm2.

'Newer' new techniques

With better understanding of hyaline cartilage biology and the limitations of the above techniques, there was a drive to develop procedures that restore rather than repair. These have been termed 'resurfacing techniques', by which articular cartilage is implanted or transferred to the defect. These include:

  • autogenous osteochondral transplantation ('mosaicplasty')
  • allograft osteochondral transplantation
  • autologous chondrocyte implantation

All of these techniques (see box below) require a stable well-aligned knee and so these procedures are often combined with osteotomies or ligament reconstructions and occasionally with meniscal transplantation.

Summing up

These new treatments appear promising for patients with cartilage defects who are either not responding to conservative measures or are not suitable for arthroscopic debridement or joint reconstruction.

Long-term follow-up studies of these techniques are needed to allow a clear picture of their benefits, indications and durability. At the moment, the choice of procedure must be made jointly by surgeon and patient, after consideration of the patient's age, size of the defect, presence of other articular problems and level of activity the patient wants to return to. Developments in understanding of cartilage repair, the development of growth/ modulating factors and genetic engineering that may enhance the effectiveness of such methods make this an exciting field of research.

The newer techniques

Autogenous osteochondral transplantation ('mosaicplasty')

  • small cylinders of bone and cartilage taken from a non-weight-bearing portion of the femoral condyle and transplanted into a hole made by removing the articular defect with its subchondral bone
  • successful for small defects of the medial or lateral femoral condyle
  • primary treatment of symptomatic small defects on femur (<2cm2) secondary treatment when other treatments have failed
  • allows immediate movement and protected weightbearing
  • main complication is technical problems with inserting the grafts
  • question-mark whether donor sites lead to problems in long-term
  • five-year follow-up suggests at least as effective, if not better, than marrow stimulation procedures

Allograft osteochondral transplantation

  • as above, but using size-matched fresh or fresh-frozen treated allografts
  • indicated for larger defects (>2cm2)
  • 75 per cent of patients reported good to excellent results up to 10 years post surgery
  • secondary treatment for failure of autologous chondrocyte implantation (see below) for defects bigger than 2cm2
  • risk of transmission of disease
  • risk of rejection response by immune system· limited availability of grafts
  • grafts must be implanted within three days

Autologous chondrocyte implantation

  • indicated for continuing symptoms, focal defect due to trauma or osteochondritis, if articular surface is generally preserved without significant degenerative arthritis or subchondral bone loss
  • healthy cartilage cells harvested arthroscopically from minor weight-bearing area in the knee
  • harvested cells are cultured· expanded, activated cells injected under a membrane that is either sewn (ACI) or glued (MACI) over the defect
  • matrix is chondrogenic· final repair tissue appears and behaves like normal hyaline articular cartilage (compared to fibrocartilage)
  • 80 per cent of patients report good results at four-year follow up
  • 90 per cent of patients return to sports or a normal lifestyle· expensive ­ involves two procedures; long nine-12 month recovery
  • reserved as a secondary procedure for small defects (<2cm2) and a primary or secondary procedure for bigger defects

Fares Haddad is consultant orthopaedic surgeon specialising in knee and hip arthroscopy, reconstruction, joint replacement and revision ­ he is clinical director at University College London HospitalsCompeting interestsNone declared Kyriacos Eleftheriou has just started his orthopaedic registrar training at University College London Hospitals after completing a MD investigating how environmental and genetic factors are involved in the regulation of bone remodelling in health, exercise and the processes of osteoporosis, bone healing and failure of joint prostheses.

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