INJURY TREATMENT

and deliver bone marrow cells to the area of injury, and also to perforate the proximal ligament itself to produce a blood clot - 'nature's glue'. This technique is only possible for genuine partial tears and very proximal ACL injury where the ligament virtually peels off the bone. The results have excited interest but are by no means certain.

THE FUTURE One day, a few weeks after aspirating bone marrow cells in the clinic from a patient with an ACL tear, a 'made to measure' ACL derived from the stem cells isolated from the bone marrow, will be delivered to the surgeon for implantation. Whilst feasible, and despite encouraging developments in laboratory work, and even clinically, this reality is years off. The various bodies involved in this work have a vested interest in creating excitement and expectancy but clinically useful techniques really remain distant.

TREATING ACL TEARS IN CHILDREN AND ADOLESCENTS These injuries are becoming more frequent. Since the patients are children and there is the possibility for causing growth disturbance from damaging the growth plates at reconstruction there was a desire to treat this patient group non-surgically. Unfortunately if left without surgery several studies show that these patients do very badly indeed, largely because it is hard to control their activity, causing severe damage to their knees. In fact by using hamstring grafts the risk to the growth plate is minimal despite the potential for significant growth post-operatively (figure 6).

RESULTS As with all surgical procedures the results published from surgeons in series paint a rather rosy picture. In uncomplicated cases I would expect, barring a complication, a professional athlete to get back to the same level of activity in virtually all cases unless they are a track athlete. Most studies quote a 95% good or excellent result rate. There is however no doubt that results in professional athletes are optimal. The real challenge is getting you or I back to the same level of activity. The reason that athletes do best is presumably related to the quality of their rehabilitation, their drive, but also their God-given neuromuscular skills which mean they can get round their problem if need be.

The quality of the result from ACL reconstruction depends on three things. Firstly the quality of the surgery which unfortunately does remain a significant variable, the quality of the patients' rehabilita- tion and their commitment to it, but importantly the state of the knee at the time of surgery.

Figure 6: Radiograph a few years after an ACL reconstruction undertaken at age 12 years showing migration of fixation devices away from the growth plate and elongation of the bone tun- nels. Furthermore comparison with the contralateral knee confirms no significant growth disturbance.

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The more 'collateral' damage par- ticularly to menisci and joint sur- faces, the more cautious one has to be about the long term out- look. In particular, loss of lateral meniscal tissue and chondral injury are worrisome.

COMPLICATIONS FOLLOWING SURGERY Serious complications are thankfully rare after this operation. Nevertheless there are some common problems.

Deep infection Deep infection in the knee should occur in only around 1 in 500 cases. This is a serious problem, but if detected promptly and dealt with by arthroscopic washout of the joint combined with high dose intravenous antibiotics and then prolonged oral antibiotics a good outcome can be achieved. In most cases the graft can be retained.

The loss of joint motion/arthrofibrosis True arthrofibrosis in which the whole joint cavity scars up is actually very rare. The most common problems are related to fat pad scarring and graft misplacement. An excessively anteriorly placed tibial tunnel will cause graft impingement on the intercondylar notch and restrict extension causing fixed flexion deformity. A build up of scar tissue at the front of the ACL graft perhaps related to impingement producing a so-called 'Cyclops' lesion will cause a block to extension. This can be remedied by resection of the scar tissue. Excessively anterior placement of the ACL graft in the femur will restrict flexion. In addition, if the ACL graft impinges on the posterior cruciate ligament flexion will also be restricted.

The most common cause of failure to achieve full extension is in cases where ACL reconstruction is undertaken prior to achievement of full extension after the initial injury (figure 7).

Fat pad scarring is the usual cause of this. If this is established, an arthroscopic resection of the scar in the fat pad and particularly opening up of the interval between the anterior inter-meniscal ligament/front of the superior tibia and the patellar tendon can overcome this problem.

In long standing cases, whilst the initial cause of fixed flexion is almost always at the front of the joint (ie. the fat pad) a secondary contracture at the posterior capsule may require treatment. Rarely a posterior capsular release is required. Via an incision allowing a posteromedial approach to the knee the capsule can be opened and the capsule and gastrocnemius tendons dissected off the posterior aspect of the distal femur from medial to lateral across the whole of the back of the knee.

Failure to get the knee straight is a source of significant problems and unhappiness. The patient can sprint with a bent knee but having a fixed flexion deformity means that the patient can never comfortably stand or walk with the knee straight, thereby having to use the quadriceps more - causing overload symptoms. Fixed flexion will tend to increase forces on the patello-femoral joint which can result in chondral damage. The fat pad scarring extending to the anterior horns of the menisci and the inter- meniscal ligament may also restrict the ability to flex by restricting posterior translation of the menisci during knee flexion.

Quite simply, fixed flexion should not be accepted even after only a few weeks. Early intervention is more likely to succeed than that undertaken later. Sadly patients are often left with this problem untreated, or simply told that 'physio' is required only to hear at later clinic visits that now 'more physio' is needed.

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