Knee injuries in sports

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Dr John Orchard, sports physician, Sports medicine at Sydney University , NSW

Inside

§         The impact of knee injuries in sport

§         Diagnosing knee injuries

§         Diagnosis and management of specific knee injuries

§         Preventing knee joint injuries

 

KNEE injuries are common in many sports and the knee joint gives rise to more surgical procedures worldwide than virtually any other structure in the body.

In AFL players knee injuries comprise more than 12% of all injuries and account for more than 20% of missed playing time. Injuries to the anterior cruciate ligament (ACL) alone account for almost 10% of total missed playing time (table 1).

Table 1: Numbers of injuries and missed games due to knee injuries in AFL players

Diagnosis	Injuries per team per season	Missed games per team per season
Anterior cruciate ligament injuries	0.9	12.8
Knee medial ligament injuries	1.0	3.6
Posterior cruciate ligament injuries	0.5	2.9
Knee cartilage injuries (meniscal and articular)	1.1	6.2
Patellar tendon injuries	0.7	2.9
Patellar instability	0.1	0.8
Other knee injuries	1.1	2.9
All knee injuries	5.4	32.1
All injuries	39.3	142.3

 

The combination of increasing average life expectancy and increasing body mass index means that most of the population will suffer a knee complaint at some time during their life.

Sporting activity is a double-edged sword for the knee joint. Although chronic knee problems often have their genesis in old sporting injuries, lack of exercise and sporting activity in later life often leads to weight gain, which increases the forces through the knee joint and makes knee pain more likely.

Clinical and imaging

BECAUSE the knee is an accessible peripheral joint it is generally easy to make an accurate diagnosis of many knee injuries using clinical examination.

For the GP assessing a knee injury it is most important to recognise the diagnostic possibilities from the history (table 2) and to be aware of which clinical diagnoses can be made without need for either imaging or specialist assessment.

A specific diagnosis is important and in many cases the diagnosis can be made through history and relatively simple physical examination findings such as localised tenderness.

Clinical diagnosis of some injuries such as those to the ACL can be difficult for examiners who lack regular exposure to managing such injuries. However, a GP with a special interest in sports injuries and who is confident with using the Lachman’s and pivot shift tests (see next section) can often make this diagnosis.

It is equally appropriate when this diagnosis is suspected to refer for specialist assessment when the GP has not had experience in knee examination or when the diagnosis is in doubt.

Although modern radiological techniques such as MRI can assist in the diagnosis of knee injuries, there is a tendency for overuse of investigations in cases where the diagnosis can be clearly established using clinical examination alone. It is important to remember that a high incidence of abnormality in normal asymptomatic knees detected on knee MRI. ²

Contact and pivoting sports injuries (usually acute injury mechanism)

·       Medial collateral ligament tear

·       Anterior cruciate ligament tear

·       Posterior cruciate ligament tear

·       Meniscal tears (in the young)

·       Prepatellar bursitis

·       Tibio-fibular sprains/posterolateral complex injuries

Running and jumping sports ‘overuse’ injuries

·       Patellar tendinopathy

·       Iliotibial band syndrome

·       Patellar tendon rupture

·       Osgood-Schlatter syndrome (adolescents)

Injuries that can occur with or without ballistic movements

·       Patellofemoral pain syndrome

·       Meniscal tears (in the older athlete)

·       Patellofemoral instability

·       Articular cartilage injuries

·       Hamstring insertional tendinopathy

 

In general the attitude towards investigation of knee injuries should fall somewhere between the potential mismanagement in an emergency department when a normal knee X-ray is used to declare than the injury is ‘minor’, and the modern (equally inappropriate) tendency to use MRI scanning to confirm every clinical diagnosis.

After an acute knee injury, ligament injuries and meniscal tears need to be diagnosed accurately, but in most cases diagnosis can be based on clinical examination (table 3). Although MRI scans are the most sensitive test for finding knee joint pathology, they are quite non-specific.

Table 3: Diagnosing the major knee injuries (clinical and imaging)

Diagnosis	Clinical diagnosis	Investigations
Anterior cruciate ligament tear	History of sudden giving way. Experienced examiners can confirm with Lachman’s and pivot shift tests in most cases	MRI useful for high-level athletes with haemarthrosis when early diagnosis is required
Posterior cruciate ligament tear	Contact injury to the ground (on a flexed knee) or clash of knees (AFL ruckmen). Positive posterior drawer	Usually not necessary
Medial collateral ligament tear	Contact valgus injury, increased valgus stress	Usually not necessary
Tibio-fibular sprains/posterolateral complex injuries	Generally hyperextension mechanism (rare injury)	MRI to assess severity and whether surgery may be required (only required in severe cases)
Meniscal tears	Combination of medial or lateral pain and joint-line tenderness, mechanical symptoms, effusion and positive McMurray’s test (see figure 5)	MRI scanning useful for assuring surgery is indicated
Articular cartilage injuries	Knee effusion and history of locking or catching may indicate a significant lesion	X-ray to assess overall state of knee degeneration. MRI for pinpointing specific lesions, but X-ray is more likely than MRI to alter management
Knee inflammatory or infective conditions	Knee effusion, pain, fever, no history of trauma (or history of invasive procedure, eg, injection or arthroscopy)	X-ray and pathology tests indicated (FBC, ESR, C-reactive protein, uric acid)
Patellar tendinopathy (or Osgood-Schlatter syndrome in adolescents)	History of sporting activity, gradual onset of pain, tenderness at either end of the patellar tendon	Ultrasound or MRI may assist with prognosis but do not generally alter management. Use X-ray instead in adolescents
Patellar tendon rupture	Sudden-onset injury, inability to support weight	Investigations indicated before surgery (ultrasound or MRI)
Hamstring insertional tendinopathy	Tenderness on medial side below joint line	Usually not necessary
Iliotibial band syndrome	History of running (or cycling), pain on slow running. Tenderness on lateral side above joint line	Usually not necessary
Patellofemoral pain	Pain with the knee bent (sitting or squatting)	Usually not necessary
Prepatellar bursitis	History of kneeling or landing on kneecap. Swelling cannot be balloted underneath the patella	Usually not necessary
Patellofemoral instability	Patellofemoral apprehension, history of dislocations	X-ray (with skyline view of patellofemoral joint) helpful

 

Plain X-rays should still be the first-line investigation for knee injuries, particularly in children, where fractures and growth plate injuries are more common, and the middle-aged or elderly, where knee joint degenerative change is very common and best assessed with an X-ray as being absent, mild, moderate or severe.

Ultrasound is rarely indicated for knee injuries: the only common indications are to assess severity of a tendon lesion such as patellar tendinopathy or to confirm that a posterior knee swelling is a Baker’s cyst.

CT scan and bone scan are also rarely required in the workup of knee injuries but are used to assess or confirm an extra-articular fracture, which is quite rare.

Anterior cruciate ligament injuries

THE knee ACL injury is rightly considered the most important acute diagnosis of the sporting knee because of its frequency and devastating impact on athletes. A report of permanent disability from soccer in Sweden showed that more than half the cases involved the ACL

Because of the high rate of osteoarthritis caused by previous ACL injury, it has been estimated that up to 10% of the total long-term cost of sports injuries is due to ACL injuries.

Although the absolute number of ACL injuries occurring in Australia is greater in males (due to their greater likelihood to play at-risk sports), numerous studies have shown that the relative risk for ACL injury in females in much greater when they play the same sports.

The most common mechanisms for ACL injury are:

·      A non-contact change of direction when the foot becomes ‘stuck’ to the surface.

·      A hyperextension on landing from a jump

·      A direct valgus force from a blow to the leg from the outside.

The clinical diagnosis of ACL instability can be made in most cases using the Lachman’s and pivot shift tests. With the Lachman’s test (figure 1), the amount of anterior drawer at 30° of flexion is relevant, but the ‘end point’ feel to movement is even more important for determining an intact ACL.

Figure 1 : Lachman's test for torn anterior cruciate ligament.

When the pivot shift test (figure 2) is performed on a deficient ACL the tibia can be subluxed forward in internal rotation (relative to the femur) with an extended knee, and relocates with passive flexion.

Figure 2 : Pivot shift test for anterior cruciate ligament instability.

Successful use of these tests requires substantial exposure to examining stable and unstable knees, which is normally not part of medical school curriculum. Most sports physicians and orthopaedic surgeons who treat knee injuries can make the diagnosis clinically, particularly in either chronic cases or in the immediate acute scenario (on the sideline).

The most difficult time to diagnose an ACL injury is in the days immediately after the injury, when there may be a large, tense haemarthrosis. At this time the accuracy of MRI examination (figure 3) may be greater than that of an experienced examiner.

Figure 3 : Anterior cruciate ligament tear seen on MRI scan (T1 sagittal).

The natural history of an ACL injury is that the ligament generally heals in a suboptimal position, meaning that the knee is prone to instability (and therefore secondary cartilage injuries) during twisting movements.

After a diagnosis of ACL injury has been made, the patient is faced with difficult decisions about surgical reconstruction and whether to return to twisting sport. A recently published algorithm recommends that the decision about reconstruction depends on a combination of patient choice, degree of knee laxity on clinical testing and desire to return to pivoting or twisting sports on a regular basis.¹

Younger patients are more likely to fail conservative treatment for ACL injuries. However, even surgical reconstruction cannot promise a completely normal knee. On return to sports such as football after reconstruction, the player has a 4-10-fold increase in the risk of re-injuring the ACL (on either the graft or contralateral side), and further surgery for cartilage injuries is not uncommon.

It has been suggested recently that amateur athletes with ACL injuries should seriously consider retiring from pivoting and twisting sports, even after reconstruction, to prevent late knee osteoarthritis.

The choice of graft for ACL reconstruction is made by the surgeon, but there have been many RCTs comparing the two most popular choices (patellar tendon graft and four-strand hamstring tendon grafts).

A consistent finding has been equivalent levels of function and patient satisfaction for each type of graft, but with trends towards greater stability in the patellar tendon graft groups and less secondary morbidity from the graft site in the hamstring tendon groups.

This means certain patients can be recommended to have certain grafts based on their relative needs for stability versus avoiding morbidity, but either graft choice is satisfactory in the hands of an experienced knee surgeon.

Other knee ligament injuries

Compared with the ACL, the clinical diagnosis of other common knee ligament injuries is easier. The posterior cruciate ligament can be diagnosed using the posterior drawer test, and medial ligament injuries assessed using valgus stress testing.

The posterior drawer is performed with the knee in 90° with the patient’s foot stabilised (figure 4); the tibia can be subluxed posteriorly in a positive test. The medial ligament is tested in 15° of flexion with a valgus force on the tibia.

Figure 4 : Posterior drawer test for posterior cruciate ligament tear.

In general, optimal management of knee ligament injuries (other than the ACL) is conservative, except in the uncommon case of multiple torn structures. Combined posterior cruciate ligament and posterolateral corner (lateral ligament plus biceps femoris insertion) injuries are best treated surgically.

Meniscal tears and articular cartilage lesions

Meniscal lesions are extremely common and can often be found on MRI in asymptomatic individuals.

Although MRI has assisted with greater accuracy in diagnosis, the decision to undergo surgery should be made on clinical grounds. Traditionally these are:

·      Mechanical symptoms (catching and/or locking).

·      Restrictions in range of movement (in the extremes of flexion or extension [figure 5]).

·      Positive McMurray’s test, being a feeling of pain and/or catching when the examiner rotates the tibia with the knee close to full flexion.

·      Recurrent knee joint effusions.

These indications should not be altered by the presence of in-substance signal change in the meniscus on an MRI scan

Figure 5 : McMurray's test for meniscal tear.

The information gained from MRI can be useful to avoid or delay surgery in a patient with knee pain due to low-grade articular cartilage degeneration (figure 6).

Figure 6 : Medial knee osteoarthritis.

A recent controversial but landmark randomised controlled trial cast serious doubt on the value of knee ‘chondroplasty’ (smoothing of roughened areas of degenerate chondral surfaces) for mild-moderate degenerative articular cartilage change, showing no improvement with chondroplasty compared with placebo surgery.²

Although the authors claimed that many thousands of unnecessary arthroscopes are performed each year, there has been no reaction from orthopaedic surgery bodies, insurance companies or government in Australia to limit the indications for this potentially lucrative procedure.

It is still felt there is a role for arthroscopic management of certain chondral lesions, but the indications should probably be limited to cases in which there are loose bodies, mechanical symptoms of locking, or recurrent large effusions rather than knee pain with evidence of degenerative change on X-ray or MRI.

In the case of a large grade-4 (full thickness) chondral lesion causing these symptoms, the standard treatment is still microfracture (or, osteoplasty, in which the surgeon deliberately damages the exposed bone to stimulate fibrocartilage growth) despite promising results with articular hyaline cartilage grafting.³

Where there are degenerative changes in the knee causing pain (but not to a degree that indicates joint replacement is needed) the best management is to recommend moderate activity, quadriceps strengthening, glucosamine tablets (which are available in many probably equivalent over-the-counter formulations) and hyaluronic acid injections.

Hyaluronic acid injections are normal given as a series of three 2mL injections on a weekly basis. Despite evidence that outcomes are improved in knee osteoarthritis,⁴ these injections are not funded by the PBS (although some private health funds provide benefits) so the patient must decide if promised benefits are worth the outlay of about $500 per course.

Patellofemoral pain syndrome

The history in this condition usually includes pain on activities that involve prolonged knee bending (such as sitting) and during knee squatting, sometimes with obvious wasting of the vastus medialis muscle.

Although patellofemoral pain syndrome is primarily a clinical diagnosis best managed conservatively, investigations using MRI suggest that subtle patellofemoral joint articular cartilage lesions are common.

Treatment includes strengthening of the muscle plus taping (figure 7) or bracing the patella (usually into a more medial position) to assist the muscle in holding the patella in its correct alignment.

Figure 7 : Patellofemoral taping.

Patellar instability

Patellar instability (dislocation or subluxation) generally affects young patients and develops either during sport or, in someone with a highly unstable patellofemoral joint, during everyday activities.

Almost all patellar dislocations are lateral because of the natural valgus angle of the leg at the knee. On first presentation a trial of conservative treatment is warranted, including use of an anti-dislocation brace and strengthening of the vastus medialis obliquus in a similar fashion that in to patellofemoral pain syndrome.

Recurrent patellar instability is best managed surgically using either a soft tissue procedure (medial augmentation and lateral release), which allows a more rapid recovery, or a bony procedure (tibial tubercle medial transfer) which is more definitive.

Patellar tendinopathy and Osgood-Schlatter syndrome

The patellar tendon is one of the major load-bearing tendons in the body, hence its tendency to overuse injury. Diagnosis of tendinopathy is clinical with a history of well-localised pain and tenderness usually just below the tip of the inferior pole in adults, or at the tibial tubercle in adolescents.

In adults the pathology is an enthesopathy (under-surface degenerative change at the bone-tendon junction), with a tendency towards chronicity, perhaps due to stress shielding of the under-surface of the tendon.

There is a combined underuse-overuse injury, with the weakened under-surface of the tendon not bearing enough load and the normal outer portion of the tendon often overloaded. Treatment therefore rarely includes either continuing with abusive loads or complete rest.

Moderate loading within pain limits, followed by gradual increases in load as the weakened section of the tendon repairs itself, and eccentric strengthening (figure 8) is often successful.

Figure 8: Eccentric quadriceps strengthening.

In adolescents the condition is an epiphyseal overload and, because this growth plate (at the tibial tubercle) is not a critical one, the condition is somewhat self-limiting. In most cases there is little need to investigate; when this is necessary, plain X-ray in adolescents and ultrasound in adults are the modalities of choice.

As with other knee pathologies, there is a high incidence of patellar tendon imaging abnormalities in asymptomatic athletes.

Management of patellar tendinopathy includes encouraging moderate loading, eccentric quadriceps strengthening (loading the muscle only as it lengthens, particularly useful for this condition when performed on a downward slope) and calf and gluteal strengthening.

Because inflammation and impingement are not generally considered significant pathologies in this condition, NSAIDs and cortisone injections are not generally recommended and surgery is also of limited value. Other newer treatment options successfully used for patellar or similar tendinopathies include nitrate patches, extracorporeal shock-wave therapy and aprotinin (Trasylol) injections.

Iliotibial band syndrome

Iliotibial band friction syndrome is a cause of lateral knee pain generally affecting distance runners. The most important diagnostic clues are in the history: the syndrome is the only knee problem in which the pain will be consistently worse during slow straight line running than in multidirectional movement.

Pain is also worse on downhill rather than level running, because the knee is in a more extended position during foot-strike. Management includes avoiding aggravating activities, local corticosteroid injection and surgery for long-standing cases.

Medial hamstring tendinopathy and pes anserinus bursitis

Tendinopathy at the insertion of the medial hamstring tendons is quite common and can even be caused by activities such as prolonged walking or cycling. The pathology usually involves the pes anserinus bursa, which lies deep to the tendon attachments.

The diagnosis is made by finding localised tenderness on the medial side of the knee distinctly below the joint line.

Although cortisone injections are losing favour as a treatment for overuse tendinopathy, they can still be justified for this condition because of the involvement of the bursa and the relative lack of concern regarding potential medial hamstring tendon rupture (as two of the four tendons that insert here are routinely sacrificed during ACL surgery, with minor consequences only).

Other knee joint diagnoses

One diagnosis that can mimic knee joint effusion or haemarthrosis is prepatellar bursitis, caused by the direct pressure when kneeling or by repetitive landing (eg, a football player who is repeatedly tackled and thrown to the ground).

Unlike an effusion that can be balloted underneath the patella from the medial to lateral side of the joint, the prepatellar bursa sits directly superficial to the patella. This bursa, which is not of major structural importance, can give rise to very significant swelling, so early aspiration and injection of cortisone is indicated. Occasionally surgical removal may be required.

Lateral knee structures, including the iliotibial band and hamstring tendons.

Medial knee structures, including medial cruciate ligament and hamstring tendons.

Some less frequent diagnoses can also mimic the common ones. For example, Hoffa’s syndrome is an intra-articular bleed of the infrapatellar fat pad that can be caused by a hyperextension injury. This may mimic ACL injury but fortunately the swelling usually settles within a few weeks with rest, and the patient can return to their sport.

The knee joint may present as one of many inflamed joints in a polyarthritis, which is diagnostically quite distinct. If the knee is a single joint affected by an inflammatory disorder, the diagnosis is often more difficult. Likely causes include gout, pseudogout (chondrocalcinosis) and seronegative inflammatory disorders.

Knee joint infection should be suspected in children and in anyone who has had a recent invasive procedure such as intra-articular injection or arthroscopy. In these scenarios blood tests to measure FBC, ESR and CRP and microscopy and culture of knee joint aspirate plus referral to a rheumatologist are indicated.

Table 4: Recommended management (conservative versus surgical) for the major knee injuries

Diagnosis	Conservative management	Surgical management
Anterior cruciate ligament tear	In patients who do not have symptomatic instability, older athletes and/or those prepared to avoid multidirectional sports	ACL reconstruction is the management of choice for the young athlete who wishes to continue with multidirectional sports
Posterior cruciate ligament tear	Usually rest for 6-8 weeks is sufficient	Rarely indicated (?only when combined with posterolateral instability)
Medial collateral ligament tear	Rest (+/– knee brace) for 1-12 weeks, depending on severity	Rarely indicated (?high level athletes with complete ruptures at the tibial insertion)
Tibio-fibular sprains/posterolateral complex injuries	Minor lateral ligament sprains can recover with 2-6 weeks’ rest	Biceps tendon ruptures and/or combined lateral and posterior cruciate ligament injuries (rare) are managed surgically
Meniscal tears	Degenerative tears in the older athlete that do not give rise to mechanical symptoms can be managed conservatively	Arthroscopic partial meniscectomy is generally the treatment of choice for mensical tears. Meniscal repair can occasionally be successful in acute peripheral tears in younger athletes
Articular cartilage injuries	Almost all mild-moderate articular cartilage injuries (extremely common) should be managed conservatively, even though complete cure is unlikely	Arthroscopic surgery for articular cartilage lesions is probably over-performed (as it also fails to cure), although it is still indicated when there are mechanical symptoms such as locking. Total knee replacement in severe cases
Patellar tendinopathy	Physiotherapy, eccentric strengthening, activity within pain limits and some other therapeutic treatments (although COX-2 inhibitors and cortisone are not recommended)	Rarely indicated
Patellar tendon rupture	Treat surgically	Acute surgical repair is the most appropriate treatment
Osgood-Schlatter syndrome (in adolescents)	Activity within pain limits, calf and gluteal strengthening, reassurance	Rarely indicated (?when impingement caused by excessive ossification)
Hamstring insertional tendinopathy	Anti-inflammatory gel, cortisone injection, eccentric strengthening	Occasionally indicated for chronic cases with bursa formation
Iliotibial band syndrome	Cortisone injection, avoidance of aggravating activities (eg, downhill jogging)	Indicated for cases resistant to conservative treatment
Patellofemoral pain	Physiotherapy, taping, strengthening	Rarely indicated (?when there is persistent knee joint effusion)
Prepatellar bursitis	Aspiration and cortisone injection (+/– antibiotics)	Indicated for cases resistant to conservative treatment
Patellofemoral instability	Physiotherapy, bracing, strengthening	Indicated for recurrent dislocations
Knee infections or inflammatory conditions	Cortisone injections for proven inflammatory conditions (eg, gout)	Hospital admission (antibiotics, lavage) for knee joint infections

 

Referral

Knee pain that does not settle requires a definite diagnosis and, when the diagnosis is not known, referral for imaging or to a specialist is required. Many, but not all, knee problems may require surgical opinion (see table 4).

Comparing tables 2 and 4 reveals that athletes participating in multidirectional sports are far more likely to suffer from problems that should be managed surgically. However, given the financial incentives in our health system favouring use of knee arthroscopy, referring all knee problems to orthopaedic surgeons, irrespective of the diagnosis, may lead to unnecessary and therefore potentially harmful operations being performed.

Knee arthroscopy.

If the diagnosis is known, failure to respond to first-line treatment is also an indication for referral. The appropriate specialist for referral depends on the provisional diagnosis.

Referral to an orthopaedic surgeon is usually the most appropriate option for advanced osteoarthritis that may require knee replacement and when multidirectional injuries in young people (ACL tears, meniscal injuries, patellofemoral instability) are confirmed or suspected.

For conditions in which even second-line treatment will be conservative (table 4), it is more appropriate to refer to either a physiotherapist (for conservative management), a sports physician (for diagnostic advice or newer non-surgical drug therapies) or a rheumatologist (for inflammatory joint disease).

GIVEN the enormous costs of sporting knee injuries and the even greater costs of inactivity (meaning that avoidance of sport cannot be recommended by health authorities), it would be assumed that preventing these injuries would be a priority for all health systems.

However, there is limited knowledge regarding prevention. In Australia, sporting bodies (such as the AFL) have led the way in funding research into preventing knee injuries, with government bodies to date largely ignoring the impact that sporting knee injuries have on the community.

Unfortunately there is a misguided cynicism associated with sporting injuries whereby they are considered basically self-inflicted and therefore not worthy of government interest. This response to sporting knee injuries can only be addressed by highlighting the worsening epidemics of obesity and inactivity in the hope that the attitude towards sports injuries changes.

A recent study showing that a structured warm-up (including balance exercises) can lower the rate of knee and ankle injuries in young athletes playing handball,⁵ should encourage further trials in this area.

There is also some evidence that playing surfaces and shoes that lead to greater shoe-surface traction increase the risk of knee injuries in football. In general, softer surfaces (such as grass or, in particular, sand) lead to greater loads being absorbed by the ankle joint and calf-Achilles complex, reducing the load on the knee joint. An athlete with a knee injury may therefore find running on sand more comfortable (as opposed to an Achilles tendon injury where the opposite may apply).

Another generalisation is that downhill running loads the quadriceps and knee to a greater extent whereas uphill running loads the hamstrings and calf more.

Having greater body weight undoubtedly puts extra load through the knee joint, so that weight loss is a sensible measure to reduce the risk of knee injuries.

A recent decision by the AFL to limit ruckmen to a 10m diameter circle at the centre bounce has the potential to reduce the rate of posterior cruciate ligament injuries, which have been shown by research to be common in this scenario.

When the diagnosis is obscured by swelling

A 27-year-old social netball player lands from a jump and feels her knee collapse beneath her. She is carried from the court and presents to your practice the next day on crutches with a painful, very swollen knee that is difficult to assess.

Examination confirms the swelling is a haemarthrosis. Range of motion is limited, but patellar apprehension is not present and the medial ligament feels intact on valgus testing. However, Lachman’s and pivot shift tests are equivocal because of knee joint spasm and swelling.

Management

An ACL tear may be suspected based on this history, with a meniscal tear the most likely differential diagnosis. Although both these diagnoses may require surgery, they are not surgical emergencies. Aspiration of the haemarthrosis is probably unnecessary, but referral to physiotherapy to reduce swelling and maintain quadriceps tone is appropriate.

If the swelling is very tense, taking NSAIDs may be worthwhile. Detailed imaging is probably not required at this stage but a plain X-ray is indicated, especially if weight-bearing is not tolerated.

Even at this early stage it is important to elucidate what the patient’s long-term goals are with respect to her sport. If she is a dedicated netball player who will definitely want to return to her sport, early surgical referral (for diagnosis and surgical management) is indicated. If she is an occasional player who would prefer to play alternate sports than undergo surgery, then a wait-and-see approach is reasonable.

The clinical diagnosis of an ACL injury becomes easier to make over time as the swelling reduces. ACL reconstruction is readily available in the private system in Australia but is unfortunately more difficult to access through the public system. For a patient who wishes to have surgical reconstruction but does not have private health insurance (a common scenario) there are three choices:

·      Join a public hospital waiting list and avoid twisting sport until recovery from 6-12 months after the operation.

·      Join a private health fund and wait the minimum (12 months) period for pre-existing complaints before arranging surgery privately (also avoiding twisting sports in the meantime).

·      Have the operation privately and pay cash (which may cost $5000-8000, but will allow a more rapid return to sport).

The management option that is definitely not recommended is to ignore the injury and continue to play multidirectional sports on an unstable knee, which can lead to rapid cartilage degeneration.

Too much too soon

A 45-year-old overweight man presents with medial knee pain, having decided to take up jogging for the first time in 20 years. He does not have a knee effusion but has well localised tenderness on and just below the medial joint line. He gets medial knee pain on squatting but can move his knee from full extension to full flexion without any catching or locking.

Management

It may be difficult to localise the exact area of tenderness in someone who is overweight; however, iliotibial band friction syndrome is ruled out because the pain is medial. This patient definitely requires a knee X-ray, because he may have early medial compartment osteoarthritis (see figure 6).

Surgical management is unlikely to be indicated because there is no mechanical restriction of movement. Even if he has a degenerative posterior horn tear of the medial meniscus (which is possible), in the presence of medial compartment osteoarthritis, surgery is unlikely to offer him a cure that would allow him to run again.

Although they may seem less significant considerations, medial hamstring insertional tendinopathy and patellofemoral pain syndrome are probably the most important diagnoses to make because conservative management of these conditions may allow the patient to return to running with minimal pain.

If the diagnosis of medial compartment osteoarthritis is made, he may benefit from weight loss, glucosamine, hyaluronic acid injections, valgus knee bracing and being encouraged to play lower-impact sports such as cycling, swimming, golf and perhaps doubles tennis.

In this scenario, it is foreseeable that he might need surgery (total or unicompartmental knee replacement) in the future, but hopefully not for 10-20 years if he manages the knee sensibly (which, ironically, may include avoiding surgery at the present time).

 

1. Fithian D, et al. Prospective trial of a treatment algorithm for the management of the anterior cruciate ligament–injured knee. American Journal of Sports Medicine 2005; 33:335-46.

2. Moseley J, et al. A controlled trial of arthroscopic surgery for osteoarthritis of the knee. N Engl J Med 2002; 347:81-88.

3. Knutsen G, et al. Autologous chondrocyte implantation compared with microfracture in the knee. A randomized trial. J Bone Joint Surg Am 2004; 86:455-64.

4. Wang C, et al. Therapeutic effects of hyaluronic acid on osteoarthritis of the knee. A meta-analysis of randomized controlled trials. J Bone Joint Surg Am 2004; 86:538-45.

5. Olsen O, et al. Exercises to prevent lower limb injuries in youth sports: cluster randomised controlled trial. BMJ 2005; 330:449.

Online resources

injuryupdate.com.au — information about elite sports injuries: www.injuryupdate.com.au

Australian Knee Clinic: www.kneeclinic.com.au

HealthInsite — knee injuries: www.healthinsite.gov.au/topics/Knee_Injuries

Brukner and Khan’s Clinical Sports Medicine. Chapter 23. Acute knee injuries: www.clinicalsportsmedicine.com/chapters/23.htm

DR ROSS WHITE
Beecroft, NSW

MR TG is a 54-year-old obese (BMI 32) lecturer who presented with a painful swollen left knee two days after jogging. At age 28 his left knee was forced into a valgus and posterior position during a trail bike accident

The X-rays at the time showed no fracture. An examination under anaesthetic by a base hospital orthopaedic surgeon showed incomplete tears of the anterior cruciate and medial ligaments, which were treated with a long leg plaster for six weeks, followed by extensive physiotherapy.

Although he eventually regained full movement, he had persisting laxity of the ligaments and an X-ray some years ago reported changes consistent with Pelligrini-Stieda syndrome.

Mr TG described transient pain and swelling of the knee during long walks over uneven ground but he gave no history of the knee locking. He has avoided activities that could strain the knee but can walk over smooth ground without difficulty. In an attempt to lose weight, he has recently taken up gentle jogging.

On examination the knee is moderately swollen and tender medially. The anterior drawer sign is positive and moderately painful. Mr TG is not keen on any surgery but would like to know if any physical therapies would help his knee to allow continue jogging.

Questions for the author

Would MRI be of any value in this case?

Repeat X-ray would be a much better initial test than an MRI scan. If he has medial compartment osteoarthritis, the management (for the time being) is going to be conservative (later in life, his symptoms may deteriorate and require joint replacement). In this scenario MRI would not be valuable, as it is not going to change management.

If the X-ray shows no degenerative changes (and Pelligrini-Steida is a remnant of the old medial ligament injury, not a degenerative change) then there is potential for MRI to reveal a medial mensical tear that might warrant arthroscopy.

Would arthroscopy or ligament reconstruction now help prevent the development of osteoarthritis and the need for knee replacement surgery in the future?

The horse has bolted with respect to ACL reconstruction. This is a great operation for allowing patients to continue multi-directional sports, but someone of this age, weight and activity level would not be advised to play these sports anyway.

With respect to development of osteoarthritis, this is highly likely to occur in this patient, given the history with no interventions (particularly surgical ones) likely to change this fact.

It has been shown that in the vast majority of cases, arthroscopy does not help arthritic knees; the only indication for it is the scenario outlined above, if his knee had minimal or absent degenerative changes and there was a medial meniscal tear.

Apart from swimming, what are suitable physical activities for Mr TG to maintain fitness and to lose weight?

Any physical activities that do not lead to knee pain and swelling are appropriate, with upper-body activities, cycling and walking being other alternatives. Whether light running sports (including, say, doubles tennis) are still suitable will depend on the degree of degenerative change.

Walking, for at least 30 minutes a day, is almost always going to be suitable activity. When the patient cannot do this without pain, the time for knee replacement has probably come (and by allowing the patient to resume walking, this operation has an important role in preventing heart disease and cancer developing through inactivity).

General question for the author

In haemarthrosis of the knee, how useful is aspiration and when should it be attempted? What are the timelines after an injury for the blood in a haemarthrosis to clot and subsequently to liquefy?

Aspiration of a knee haemarthrosis is not a procedure I regularly perform. Knee haemarthroses are likely to recur soon after aspiration but will also spontaneously reduce in size over time with rest. A cortisone injection would reduce the subsequent swelling, with the trade-off that an infection would become more likely.

As alluded to, a ‘fresh’ haemarthrosis and a blood-stained effusion could both be successfully drained in the clinic, but in between these two stages a knee filled with blood clot might lead to a failed attempt. Performing the procedure under ultrasound guidance is a good way to make sure the needle tip is not sitting inside a large blood clot.

 

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