by Dr. Frank Noyes

Based at the Cincinnati Sportsmedicine and Orthopaedic Center in the USA, Dr Frank Noyes is one of the world's most prominent figures when it comes to knee surgery. A prolific researcher and writer, he has published over 200 studies and articles in the world's top orthopaedic journals and textbooks, changing the face of sports medicine and orthopaedics as we know it. He serves on eight editorial review boards and is a manuscript reviewer for more than seven internationally respected journals.

Meniscal transplantation provides hope for the many thousands of patients in whom total meniscectomy has altered the shock-absorbing qualities of the knee, with consequent stresses in the vertical alignment of the lower limb and damage to the joint surfaces. But meniscal transplantation is still in its early days. The pioneers of this procedure are carefully reviewing their patients after the first three or four years - and presenting their findings, concerns and recommendations.

This paper summarises a peer-reviewed publication in the Journal of Bone & Joint Surgery of July 2004 (Meniscal Transplantation in Symptomatic Patients Less Than Fifty Years Old Noyes et al. J Bone Joint Surg Am.2004; 86: 1392-1404) presenting the results of thirty eight meniscal transplant patients nearly four years after surgery.

The study was prospective - i.e. evaluation was begun before surgery was undertaken, allowing comparison of the results of surgery with the pre-operative findings.

An evolving science

Meniscal surgery has evolved through a number of phases, and it is now well recognised that meniscal tears amenable to suture (stitching) should be repaired rather than removed. However, if considerable damage has occurred it may still in some cases be necessary to remove the greater part of this important shock-absorbing structure, leaving the knee vulnerable to stress.

That transplant should restore the load-bearing function is generally accepted, but amongst clinicians there is a considerable lack of agreement, not only about the actual efficacy of the procedure, but also about the methods of ‘harvesting’ and sterilising the donor meniscus.

Our patient series

The series included thirty-eight patients (20 male, 18 female, average age 30 years) but forty meniscal transplants, as two patients had both medial and lateral (inner and outer) menisci transplanted.

All patients consented to the surgery and to participate in ongoing evaluation. Official permission was obtained from the appropriate professional body for the special MRI studies.

All but one patient returned (average 40 months) for clinical evaluation, and the one who could not return posted all the questionnaires and was subsequently interviewed.

Indications for surgery

Prior to undertaking this study we had drawn up a clear list of indications for transplant surgery:

• prior meniscectomy
• age 50 or less
• pain in the tibio-femoral compartment (between tibia and femur bone)
• no radiographic evidence of advanced joint damage
• 2mm or more joint space on the affected side when X-rayed weight-bearing

Factors that we considered contraindications to meniscal transplant included -

• advanced joint surface damage
• significant axial mal-alignment (bow legs or knock knees) consequent on the loss of the meniscus
• knee joint instability where the patient had refused to have ligament reconstruction at the same time as the transplant
• very stiff or wasted knee or prior joint infection.

Patients in the series agreed to ligament reconstruction or repair where appropriate. They also agreed to joint surface repair (osteochondral autograft - where little plugs of healthy joint cartilage from less important areas are swapped with damaged bits on the weight-bearing surface).

Pre-operative Workup

The patient’s symptoms and signs were carefully documented before surgery was undertaken.

All patients underwent MRI imaging. Standing X-rays were taken with the knees bent to optimise visualisation of the joint space while load bearing. Any cruciate laxity was objectively measured and documented.

A sophisticated rating system was developed to allow us to assess the success or failure of the transplant surgery based on symptoms, clinical examination, MRI, X-rays, and follow-up arthroscopy.

The Surgical Procedure

The approach to the meniscus differed depending on whether the transplant was being done on the lateral or the medial side. Lateral meniscal transplant was performed arthroscopically, but we opened the joint for the medial side as the technique is more complex.

Both medial and lateral grafts depend on the donor meniscus being prepared with bone plugs, which are embedded into holes prepared in the recipient bone. The rim of the meniscus is sutured to the capsule.

Full details of the procedure can be obtained from our original publication.

Rehabilitation

Emphasis was given to minimising weight-bearing to allow the graft to heal without displacement, and toe-touch only was permitted for the first two weeks. A long leg brace was prescribed for eight weeks, with quads exercises and ROM (range-of-motion) exercises of 0-90 degrees from the first day.

ROM was increased to 135 degrees by four weeks. Weight-bearing was increased to 50% of body weight by the end of the first month.

Patients who had had a cruciate reconstruction underwent a more restricted protocol, and where osteochondral autograft had been done the patient was given an unloader brace to take some of the pressure off that side.

Balance, proprioception and closed chain exercises were started once the patient was fully weight bearing (see KNEEguru dictionary for explanation).

So what were the results after 40 months?

This paper is the first report, as far as we know, where the outcome of meniscal transplant has been evaluated in patients with concomitant ligament or joint surface damage.

Four of the transplants in three patients failed in the early days and had to be removed. Only 43% of the menisci looked completely normal at the end of this period. Nonetheless 89% of patients rated the knee as improved overall and 76% returned to low-impact sport without problem. None returned to high impact sport, and we want to emphasise that meniscal transplantation does not allow a patient to return to vigorous sporting activity.

In our opinion the outcome of meniscal transplant is best if done before there is much damage to the joint surface (’arthrosis’), and we want to point out to younger patients to avoid high impact loading activities after meniscectomy to protect the joint surfaces for the future.

We do not advocate prophylactic (’preventative’) meniscal transplant, but in those younger individuals who might later benefit from the procedure we advocate that their clinician keep a careful eye over time on the state of the joint surfaces and underlying bone using relevant imaging techniques (45 degree postero-anterior weight-bearing X-rays, spiral computerised axial tomography (CAT scan) and magnetic resonance imaging (MRI scan) with use of proton-density, fast-spin-echo techniques).

If deterioration becomes evident in an unsymptomatic patient under 50, then we do advocate meniscal transplant, with the aim of restoring load sharing, shock absorption and joint cartilage protection. But it is important that we point out that long-term results are simply not available at this time as the procedure is simply too new.

What our study has shown - and this is an important finding - is that osteochondral autograft, at least in his series, allowed pre-existing joint surface damage to be proactively managed without prejudicing the transplant, and the same with cruciate ligament reconstruction.