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Injury Prevention

A Review of Knee Rehabilitation Methods

Dr Larry McDaniel and Callin Haar investigate which rehab methods should be used with different types of knee surgery. The knee injuries selected for review include the anterior cruciate ligament (ACL) and osteoarthritis.

Multiple studies have been completed comparing two different rehabilitation techniques, but these studies do not compare more than two methods at a time. The focus of this study will be to compare two common knee rehabilitation techniques hydrotherapy and land-based exercises. The land-based exercises include neuromuscular training (NT) and strength training (ST). Strength training rehabilitation techniques include perturbation (P), open kinetic chain exercises (OKC), and closed kinetic chain exercises (CKC).

The function of perturbation training is to apply potential destabilizing forces to the injured knee. This process will enhance the neuromuscular responses of the knee that stabilize the joint (Fitzgerald et al. 2000)[3]. Open kinetic chain exercise is a non-weight bearing exercise using forces applied to the foot when the foot is not in a fixed position. This process will assist in strengthening the knee.

Closed kinetic chain exercises are weight-bearing exercises with the foot placed in a fixed position (Fitzgerald et al. 1997)[4]. Even though there is no one best method for knee rehabilitation, one form of rehab training may be more effective than another. Which techniques to be used for repair depend on the post-rehabilitation goals of the patient (Fitzgerald).

Findings related to the selection of various rehabilitation techniques were inconclusive. However, Silva et al. (2008)[6] stated that there was little difference between the end-strength of the knee when comparing the land-based to hydrotherapy. The main difference was that there was less pain in the injured knee when a person went through hydrotherapy compared to the performance of land-based exercises. The scale for the end mean of pain for a hydrotherapy patient was 15.1, with a standard deviation of 19.8. The scale for the end mean of pain for a patient going through land-based exercises was 33.4, with a standard deviation of 31.7 (Silva et al. 2008)[6].

Fitzgerald stated that although there were no statistical facts, charts demonstrated that the knee joint would stabilize if the patient did use perturbation training. The reason for this finding was that perturbation caused the knee to destabilize, which forced muscles that were weak to become active and stronger. These muscles would then assist the related muscles in the rehabilitation process (Fitzgerald et al. 2000)[3]. Andersen et al. (2006)[1] found that the seated exercise that isolated on the quadriceps femoris muscle was the most effective in tests performed to strengthen the knee joint. The quadriceps muscles are stronger and develop faster than the hamstrings. The hamstrings are the muscles that flex, laterally, or medially rotate the knee.

The The Engebresten et al. (2007)[2] study showed that the NT patients completed therapy with better overall extension. The result for an extension at 60 degrees for ST patients was 67.3, with a standard deviation of 16.1, and the NT was 79.1, with a standard deviation of 17.1. The results for flexion differed for ST patients. The ST patients produced results for a mean of 88.3 and a standard deviation of 14.4 compared to NT patients, with 86.3 for the mean and a standard deviation of 14.3. These results showed that NT is an effective way of training. The results were similar for knee flexion exercises; performance of the extension exercises revealed NT training to be the most effective method of rehabilitation. An additional form of rehab included tests that involved patients performing a one-legged jump and a triple jump.

The NT patients' overall score and standard deviation were lower than the ST patients. The one-legged jump scores were 84.9 +/- 10.9 for NT patients and 81.0 +/- 18.2 for ST patients. The triple jump test scores were 88.5 +/- 10.4 for NT patients and 83.1 +/- 15.4. No significant differences were found between the two forms of therapy. The neuromuscular and strength-training modes of rehabilitation produced similar results.

In a table of statistical data, the mean torque for the comparison between the injured and non-injured knee, the mean torque for CKC pre-test was 0.31 and post-test was 0.50. The CKC standard deviation for the pre-test was 0.21, and the post-test was 0.22. The mean torque for OKC pre-test was 0.26, and the post-test was 0.47. The pre-test standard deviation for OKC was 0.15 and the post-test was 0.19. These statistics demonstrate little difference between the open kinetic chain (OKC) and closed kinetic chain (CKC) forms of therapy. The data revealed that closed kinetic chain therapy results were varied, but the result was superior. The open kinetic chain therapy data demonstrates a lower result, but this type of therapy has provided more consistent results between patients (Morrissey et al. 2002)[5].

Some suggestions for safety tips related to rehabilitation using the above modalities would include gradual or graded knee rehabilitation. Rushing the rehabilitation process may cause damage to the knee and related joints. At the start of the rehabilitation process, most exercises should be performed without weights. Applying too much pressure on the injured leg could cause irritation and swelling in the knee (Fitzgerald et al. 2000)[3].

In conclusion, not one mode of therapy works in one particular rehab situation. The literature stated that multiple forms of treatment must be applied to rehabilitate the injured knee completely. An additional study should be performed to investigate the effects of knee rehabilitation if hydrotherapy, perturbation, and open kinetic chain therapy were combined in the process of knee rehabilitation. When combined, these forms of treatment may reduce unnecessary impact from running, stabilize the knee, and strengthen the knee muscles.


  1. ANDERSEN, l. et al. (2006) Neuromuscular Activation in Conventional Therapeutic Exercises and Heavy Resistance Exercises: Implications for Rehabilitation. Physical Therapy, 86 (5), p. 683-697
  2. ENGEBRESTEN, L. et al. (2007) Neuromuscular Training Versus Strength Training During First 6 Monts After Anterior Cruciate Ligament Reconstruction: A Randomized Clinical Trial. Physical Therapy, 87 (6), p. 737-750
  3. FITZGERALD, K. et al. (2000) The Efficacy of Perturbation Training in Nonoperative Anterior Cruciate Ligament Rehabilitation Programs for Physically Active Individuals. Physical Therapy, 80 (2), p. 128-140
  4. FITZGERALD, K. (1997) Open Versus Closed Kinetic Chain Exercise: Issues in Rehabilitation After Anterior Cruciate Ligament Reconstructive Surgery. Physical Therapy, 77 (12), p. 1747-1754
  5. MORRISSEY, M. et al. (2002) Effects of Distally Fixated Versus Nondistally Fixated Leg Extensor Resistance Training on the Knee Pain in the Early Period After Anterior Cruciate Ligament Reconstruction. Physical Therapy, 82, (1), p. 35-43
  6. SILVA, L. E. et al. (2008) Hydrotherapy Versus Conventional Land-Based Exercise for the Management of Patients with Osteoarthritis of the Knee: A Randomized Clinical Trial. Physical Therapy, 88, (1), p. 12-21

Page Reference

If you quote information from this page in your work, then the reference for this page is:

  • McDANIEL, L. and HAAR, C. (2008) A Review of Knee Rehabilitation Methods [WWW] Available from: [Accessed

About the Authors

Dr Larry McDaniel is an associate professor and advisor for the Exercise Science program at Dakota State University, Madison SD USA. He is a former All-American in football and Hall of Fame athlete & coach. Callin Haar is a student enrolled in Exercise Science at Dakota State University.