Below you will read about some of the treatment dilemmas that the sport physician is faced with when dealing with a partial tear of the anterior cruciate liagment, they include:
Definition of a Tear
Clinical Assessment
Treatment Options
Indications for Surgery
Outcome Determinants
Definition Of A Tear
The definition of the partial tear is:
History of injury to the anterior cruciate ligament
Positive Lachman test with a firm end point
Negative pivot shift test
Arthroscopic evidence of injury to the anterior cruciate ligament.
KT-1000 side to side difference of < 5 mm.
The natural history of the partial tear is controversial. There have been reports that suggest that both conservative and operative treatment give good results. The paper by Noyes had a 50% incidence of instability in high demand sports participation athletes with a anterior cruciate ligament tear > 50%. They also had a 75% incidence of re-injury. This suggests that patients in high demand sports require reconstruction.
The paper by Freunsgaard had good results with conservative treatment in patients who avoided high demand athletics.
Buckley reported that the degree of anterior cruciate tear did not correlate with outcome. Only half of their patients were able to resume their previous level of sports.
Clinical Assessment
Clinical Examination
Lachman test
Pivot shift test
KT-1000
MRI
Arthroscopy and examination under anaesthesia.
The Lachman Test
The lachman test is positive, but there is a firm end point. This anterior excursion is greater than the opposite side.
Pivot Shift Test
The pivot shift test must be negative to be a partial tear. If the test is positive, this is a clinically unstable knee and should be regarded as anterior cruciate deficient. This is the most important assessment of the partial tear.
The KT-1000 Arthrometer
The KT-1000 arthrometer will normally show a side to side difference of < 5 mm.
The slope of the curves that are pulled with the KT-2000 demonstrate the difference. This graft is a force displacement curve. On the vertical axis is the force applied to the knee, 15, 20, 30 pounds; on the horizontal axis is the mm of displacement.
The curve on the left shows the normal anterior cruciate ligament. The middle curve shows that there is initially more displacement, but then has a firm restraint to anterior translation. This corresponds to the firm end point to the Lachman test. The third curve on the right is the anterior cruciate deficient knee with complete rupture. The harder the pull, the more the displacement.
MRI
It is difficult to estimate the degree of tearing with the MRI, and it is not very useful to diagnosis partial tears of the anterior cruciate ligament. This MRI shows a small band where the anterior cruciate ligament should be. It is difficult to estimate how much of the ligament is still present.
Arthroscopic Assessment
The arthroscopic assessment of the anterior cruciate ligament tear is difficult for 2 reasons. First, it is hard to see the ligament without removing the synovium and fat pad. Second, it is only an estimate of the degree of tearing of the ligament.
It seems to be best to try and estimate whether the tear is less than, or greater than 50%. A hook probe must be used to examine the ligament proximally to see where the ligament is attached, the side wall, the roof or the posterior cruciate ligament. The best position is to be attached to the side wall in the normal position of the anterior cruciate ligament. The most common situation is to see the ligament attached to the posterior cruciate ligament.
The photo here is the appearance of the ligament proximally. It has attenuated down to a small band attached to the side wall. This may give a 1+ Lachman test, and a negative pivot shift test, but would not stand up to vigorous pivoting activities. The right photo shows the use of the hook to examine the ligament proximally. This example is lax, but is less than 50% tear. This amount of ligament should allow a return to sports.
Treatment Options
The treatment options are:
Give Up or Modify Ssports Activities
The patient who can modify his sports activities and avoid pivotal sports will do well with a partial anterior cruciate ligament injury. This is the only parameter that the individual has control over, and that point should be emphasized when counseling athletes.
Brace and Arthroscopy
The use of a brace with activity modification can be successful. Sometimes the patient will still have giving way sensation, but this may be due to a meniscal injury. The best outcome for the young patient is to have a meniscal repair.
ACL Reconstruction
If there is a positive pivot shift test, and the athlete wants to be active in pivotal sports, they should consider anterior cruciate ligament reconstruction.
Indications for Surgery
Competitive pivotal athlete in soccer, rugby
Clinical Instability
History of giving out
Positive Lachman and pivot shift test
KT-1000 > 5 mm side to side difference
Outcome Determinants
Activity Level
Stability of knee
Meniscal damage
Chondral damage
References
1.Noyes FR, Mooar LA, Moormand CT, McGinnniss. Partial tears of the anterior cruciate ligament. J Bone Joint Surg 1989; 71B:825-833 2.Fruensgaard S, Johanne\sen HV. Incomplete ruptures of the ACL. J Bone Joint Surg 1989; 71B:526-530 3.Buckley SL, Barrack RL, Alexander AH. The natural history of conservatively treated partial ACL tears. Am J Sports Med 1989; 17;221-225
