Muscle strength and hop performance criteria prior to return to sports after ACL reconstruction.

Department of Orthopaedics, Lundberg Laboratory for Orthopaedic Research, Sahlgrenska University Hospital, 413 45 Göteborg, Sweden.
Knee Surgery Sports Traumatology Arthroscopy (Impact Factor: 2.68). 09/2011; 19(11):1798-805. DOI: 10.1007/s00167-011-1669-8
Source: PubMed

ABSTRACT The purpose of this article is to present recommendations for new muscle strength and hop performance criteria prior to a return to sports after anterior cruciate ligament (ACL) reconstruction.
A search was made of relevant literature relating to muscle function, self-reported questionnaires on symptoms, function and knee-related quality of life, as well as the rate of re-injury, the rate of return to sports and the development of osteoarthritis after ACL reconstruction. The literature was reviewed and discussed by the European Board of Sports Rehabilitation in order to reach consensus on criteria for muscle strength and hop performance prior to a return to sports.
The majority of athletes that sustain an (ACL) injury do not successfully return to their pre-injury sport, even though most athletes achieve what is considered to be acceptable muscle function. On self-reported questionnaires, the athletes report high ratings for fear of re-injury, low ratings for their knee function during sports and low ratings for their knee-related quality of life.
The conclusion is that the muscle function tests that are commonly used are not demanding enough or not sensitive enough to identify differences between injured and non-injured sides. Recommendations for new criteria are given for the sports medicine community to consider, before allowing an athlete to return to sports after an ACL reconstruction.

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    ABSTRACT: Isometric and isokinetic knee strength deficit was examined on patients with anterior cruciate ligament (ACL) injury before and after ACL reconstruction. Muscle strengths of the uninjured and injured knees were measured from an ACL injured (n=12) and a control (n=15) groups. Five isometric (10, 30, 50, 70 and 90° of knee flexion) and five isokinetic (50, 100, 150, 200 and 250°·s) strengths of quadriceps and hamstrings were measured pre- and post-reconstruction (3 and 6 months). Compared to the controls, the uninjured knee showed normal strength and patterns of length-tension and force-velocity relationships. Compared to the uninjured knee, the injured knees showed a generally 25%-30% decrease in quadriceps and hamstrings strength with normal patterns of length-tension and force-velocity relationships. By 3 months after reconstruction, weakness of quadriceps of the injured knees was exacerbated, particularly at lengthened positions (about 40% of the uninjured knees at knee flexion 70° and 90°) and at slower velocities (about 35% of the uninjured knees at the 50°·s and 100°·s, p<0.05), with flattened patterns of mechanical output. By 6 months after reconstruction, quadriceps of the injured knees still showed significant weakness (about 50% of the uninjured knees) in both contraction types (isometric at knee flexion 90° and isokinetic at 50°·s, p<0.05). Hamstrings of the injured knees had not shown significant changes after reconstruction. A strengthening program placing emphasis on greater knee flexion angles and slower movement speed with sufficient training duration post ACL reconstruction is recommended due to long-lasting and exacerbated weakness during 3 and 6 months post-reconstruction.
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