Degenerative meniscal tears

Recent Advances

femoral ligaments, buckled menisci and gas within the joint. Fluid within a normal synovial recess must be differentiated from meniscocapsular junction separation. Meniscal tears are diagnosed when there is increased signal intensity extending to an articular surface or free edge of the meniscus and intrameniscal degenerative change is present when increased signal intensity remains confined within the meniscus and does not extend to a surface. Potential for inaccuracy exists when determining whether or not increased signal intensity extends to a meniscal surface. There is a tendency for MRI to suggest that signal intensity changes do extend to a meniscal surface although no arthroscopically visible meniscal tear is present. At the time of resection of a torn meniscus, the recognized extent of the meniscal tear at arthroscopy is invariably less than the extent of increased signal intensity within the meniscus as depicted on MRI. Consequently, following resection, it is possible to create an appearance that simulates a tear in the remaining meniscus. Caution in suggesting a recurrent tear is therefore necessary in the evaluation of post-operative menisci. The displaced bucket-handle tear may cause difficulty in interpretation if it is not appreciated that the meniscus is truncated and the displaced fragment is partially obscured in the intercondylar region. Occasionally the detached fragment may be very closely apposed to the remaining meniscus and MRI can fail to identify the tear, providing a further source of false negative examinations. MA1 has a high negative predictive value in the assessment of meniscal tears. This justifies a conservative approach in a patient in whom the requirement for surgery is in doubt and the MRI examination demonstrates normal meniscal appearances.

Meniscal problems in childhood M. Jackson

Andrew

As a general principle, meniscal problems in childhood should be treated as conservatively as possible. The quoted incidence of discoid meniscus is between a low of 1.4% up to 16% in Japan. A cadavar study in the UK found 5% of lateral menisci were discoid and had probably remained asymptomatic throughout life. Allowing for a 3 or 4% incidence of discoid meniscus at arthroscopy, the incidence in the UK would seem to be between 8% and 10%. The discoid meniscus has been classified into three types: (1) Complete ‘slab’ type of meniscus - silent unless torn. This completely divides the lateral compartment and completely covers the lateral tibia1 plateau. There is a rolled medial edge and perhaps this can be regarded as nature’s ‘interposition arthroplasty’. It is conceivable that this kind of meniscus is evolving from a phylogenetic point of view, rather than becoming extinct. The normal lateral meniscus is much larger than the medial. (2) The incomplete meniscus is in effect a wide lateral meniscus which usually has a thin medial edge lying between condyle and tibia1 plateau which is not completely covered. (3) The Wrisberg-type meniscus has a deficient, or absent, posterior attachment to the

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tibia and is attached to the femur by the ligament of Wrisberg. Probably these menisci always clunk. At arthroscopy the posterior attachment to the tibia should be sought as part of the assessment and the meniscus is inspected. The under-surface is difficult to see and a pre-operative MRI scan is extremely useful when this is a suspected diagnosis. When a discoid is suspected, the anteromedial portal should be the starting point of the arthroscopy. The origins of the discoid meniscus are still uncertain. Smillie suggested arrested embryological development, but other workers have stated that the meniscus does not have a discoid shape at any stage during fetal development. However, some state that the early embryo meniscus is a thick mesodermal plate, provided that you look early enough. Perhaps Smillie is right. Radiologically, discoid menisci are seldom detectable by simple widening of the joint space. Arthrograms provided useful information, but MRI is now the investigation of choice though the distinction between Wrisberg and non-Wrisberg is still an operative one. Treatment is along the following lines. For the Wrisberg discoid meniscus, if there are no symptoms no treatment should be recommended. A painful clunk probably requires total meniscectomy, but thought has been given to saucerizing the meniscus and perhaps securing it posteriorly. These patients have a dysplastic lateral compartment and perhaps the writing is on the wall for this sort of knee from the start. Degenerative meniscal tears Paul Aichroth

In the acute meniscal injury in the young person, the vertical tear produces a bucket-handle displacement or large tag. This is most commonly posteriorly and radial tears may occur, particularly on the lateral side. In the middle-aged patient, or in those with a long history of high physical activity or sports, the degenerative type tears are important and now constitute a large group with knee pain, irritability, tenderness, some swelling and definite loss of function. The degenerative meniscus tear is also part of an early osteoarthritic change in the middle aged or elderly knee - again particularly in the active or sports-playing group. A previous history of major activity is usually given. There are several features of the morphology of degenerative meniscal tears: The horizontal cleavage tear is the classic degenerative lesion. There may be a posterior segment tag or flap tear. The posterior segment may be shattered. The whole posterior segment may be shredded. Pain is usually over the medial aspect and occurs on weight-bearing, walking and particularly on rotation. The pressure of one knee against the other-particularly at night - procedures tenderness and then an ache. Catching is a frequent symptom and locking rarely occurs, and only then if there is a true bucket-handle element. Giving way constitutes an abnormal movement of the flap or tag tear posteriorly and produces this feeling of instability, particularly when turning corners or on stairs. Physical signs are muscle wasting, and intermittent swelling with an effusion. A cyst may be associated,

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particularly on the lateral side. Associated degenerative features include a mal-alignment and flexion contracture. At diagnosis the above clinical features are present. There may be a response to physiotherapy with substantial improvement on mobility and strengthening exercise. The Fairbank’s sign becomes positive and subsequent early degenerative radiological features are present. An abnormal signal in the posterior segment of the meniscus on MRI is common in the middle-aged and elderly. Degenerative splits within the substance of the posterior segment may be seen without the changes interrupting the surface of the meniscal structure. These degenerative changes may then disturb the surface with a cleavage-type lesion. The shattered posterior segment is easily detected on MRI. There are various modes of treatment. Physiotherapy consisting of mobility and strengthening exercises, together with increasing activity, may be enough to satisfactorily settle the symptoms from an early degenerative meniscal lesion. Weight loss is important in the middle-aged and elderly obese patient. Arthroscopic partial meniscectomy and rarely a total meniscectomy can be performed as can meniscectomy and compartment debridement. It should be noted that there is IZO indication for meniscal suture in such degenerative meniscal tears. The posterior segment may require removal, using an arthroscopic ‘banana’ knife to start the dissection. This continues with the arthroscopic punch scissors and the posterior segment is then removed with appropriate rongeurs. The degenerative segment may require removal piecemeal, using a selection of punches, duck-billed punches, posterior-segment punches and rongeurs. The powered meniscotome is then used to remove irregular fragments and rim trimming. To study meniscectomy in arthroscopic debridement of the knee affected by early osteoarthritis we reviewed over an 11 year period - 1977 to 1988 - 276 knees with degenerative changes in 254 patients. These were treated by arthroscopic debridement and the most important part of this operative procedure was the treatment of the meniscal lesion. Of the 276 total, 224 were affected by meniscal tears: 190 were medial and 45 were lateral, with the posterior one-third being the most commonly affected. The posterior flap or tag tear was the most common type. In our study, 142 knees (51%) were treated by a meniscal and chondral debridement, and this was associated with 68% excellent or good results. Those with less severe degenerative changes, and treated by meniscal debridement alone (104 knees) had 86% excellent or good results, and so in early degenerative changes, meniscal surgery is important and very worthwhile. In conclusion, degenerative meniscal tears are frequently found. The posterior segment medial meniscus lesion is most common. Horizontal cleavage ‘tears, posterior tag tears, shattered and shredded posterior segments are found in degenerative menisci. Degenerative meniscal tears occur particularly in middleaged sports-active patients. Degenerative meniscal lesions are present in early degenerative arthritis of the knee. Arthroscopic meniscectomy may be required and

in the degenerative added. Rehabilitation

joint further debridement

and successful arthroscopic

may be

surgery

Tracy Maunder The aims of rehabilitation are to restore motion, strength and a pain-free joint as rapidly as possible. Each rehabilitation programme is tailored to the physical and psychological needs of the individual patient. The patient must be encouraged and motivated to ensure maximal participation. The close involvement of the surgeon links the rehabilitation to the objectives of surgery. Progress benchmarks for partial meniscectomy without associated pathology are, at 7-10 days, no pain or effusion, and at 2-4 weeks, a return to activities; and for degenerative meniscal tears are, at 24 weeks, no pain or effusion, and at 6-8 weeks, a return to activities. Stages of rehabilitation consist of pre-operative and immediate post-operative treatment, and long-term rehabilitation. Pre-operative treatment ideally consists of physically preparing the knee for surgery using exercises and electrotherapy as appropriate, and to explain the process so the patient understands and is mentally prepared. Immediate post-operative treatment consists of reducing effusion by using cryotherapy and electrotherapy, increasing joint motion, strength and flexibility of musculature by initiating an exercise programme to include stretching, static quadriceps work, flexion exercises and gait re-education. Long-term rehabilitation should incorporate closed kinetic chain exercises as soon as pain and effusion allows. During this type of exercise, the foot is fixed while the hip, knee and ankle move simultaneously over that fixed point. Closed kinetic chain exercises result in: improved functional stability and proprioception thereby helping to regain normal neuromuscular control of the knee; achieving larger strength gains by using a combination of isometric, concentric and eccentric muscular contraction rather than any one alone during each repetition of the exercise. Improved specificity of training by using exercises that approximate the desired activity. Examples are: cycling, stair machine, stepping exercises, squats, lungs, hydrotherapy, balancing on a wobble board, sports cord exercises, and treadmill walking and running. For contact sports and where explosive strength is necessary, the patient must be taught agility skills and plyometric exercises such as cutting manoeuvres, figureof-eight running, jumping, hopping and landing. Patient’s progress can be monitored accurately by isokinetic muscle-testing machines (e.g. Cybex). These computer-based systems generate graphical and numerical data on the strength, power and endurance of individual muscles. This information highlights areas of residual weakness and whether a patient is strong enough to return to his chosen sport. The isokinetic machines can also be used as part of the rehabilitation treatment and are useful motivational tools as goals can be quantified. In conclusion successful rehabilitation has three key ingredients: psychological preparation and motivation