Healing of Soft Tissue: Time Constraints

William Stanish M.D., F.R.C.S.(C), F.A.C.S.
Professor of Surgery, Dalhousie University
Halifax, Nova Scotia, CANADA

Introduction To Rehabilitation
The Random House dictionary defines rehabilitation as "to restore to a condition of good health; ability to work, etc." Clearly the impression is that rehabilitation is directed towards "normalization" rather than attempting to achieve the ill-conceived notion of completely normal tissue. The objective of rehabilitation is to achieve healing.

The definition of healing is "to make whole or well." (Ref: Random House Dictionary, Ballantine Books, New York, 1980. Oxford Dictionary for Scientific Writers and Editors, Oxford University Press, 1992.)

Within the definition of healing, it is clear as orthopaedic surgeons that it is our desire to:

1. restore anatomy
2. restore function

(Ref: Stanish WD, Lai A. New Concepts of Rehabilitation Following Anterior Cruciate Reconstruction. Clinics in Sports Medicine, Vol. 12:1, January 1993, pgs. 25-58.)

Addendum: Social factors to be considered

1. Unrealistic expectations of the patient.
2. Peer pressure for "accelerated" rehabilitation.
3. Financial pressures of the marketplace.

Biological Facts of Soft Tissue Healing

1. All mesodermal tissues are in a constant state of equilibrium. "The milieu interieur" --Claude Bernard
2. All tissues of the musculoskeletal system have a threshold above which they fail. ACL - 2000 Newtons, Achilles tendon - 4000 Newtons, Hyaline Cartilage - 25 mPa/m2. (Ref: Noyes FR. Functional Properties of Knee Ligaments and Alterations Induced by Immobilizations. Clinical Orthopaedics; 123:210, 1977. Komi PV. In Vivo Registration of Achilles Tendon Forces in Man. International Journal of Sports Medicine, 8:3-8, 1987.)
3. After injury, musculoskeletal tissues never return to normal, either mechanically or architecturally. (Ref: Ng YF, et al. Long Term Study of the Biochemistry and Biomechanics of ACL - Patellar Tendon Autografts in Goats. J. of Orthopaedic Reseach, 1996; 14:851-856.)
4. All techniques of rehabilitation have limitation. Such strategies can only "normalize" injured tissues. (Ref. Stanish WD, Curwin S. Special Techniques and Rehabilitation; Crucial Ligaments 2nd Edition, Eds. John A. Feagin, pgs. 773-785, 1993.)

Factors Which Impede Healing (Systemic)

1. Age
2. Mal-nourishment
3. Corticosteroids/NSAIDs
4. Diabetes
5. Anti-coagulants

Factors Which Maximize Healing (Systemic)

1. Adequate nutrition
2. Calcitonin
3. Vitamin A
4. Glucosamine
5. Anabolic Steroids

Factors Which Impede Healing (Local)

1. Prolonged immobilization
2. Rigid fixation
3. Excessive soft tissue gap
4. Excessive motion or stress/repeat injury

Factors Which Maximize Healing (Local)

1. Electrical stimulation
2. Injectable growth factors
3. Surgical gap closure/surgical
4. Controlled motion

(Ref: Stanish WD, Rubinovich M, Kozey J, MacGillvary G. The Use of Electricity in Ligament and Tendon Repair. The Physician and Sports Medicine; Vol. 13:8, August 1985. Buckwalter JA, Cruess RL. Healing of Musculoskeletal Tissues. Fractures In Adults. Eds. Charles Rockwood, David Green, Robert Bucholz; 3rd Ed. pgs. 181-222, 1991.)

Injuries To Tendon/Ligaments

Introduction
When injured, tendon ligaments go through virtually identical phases of healing.

Phase I - Inflammatory
Phase II - Proliferative
Phase III - Remodelling

(Ref: Woo SLY, Buckwalter JA. Injury and Repair of Musculoskeletal Soft Tissues. Am. Academy of Orthopaedic Surgeons Symposium, Illinois 1988.)

Example No. 1: Forty-year-old squash player/rupture of the Achilles tendon.

Clinical Experience
A complete rupture of the Achilles tendon requires surgical repair of reconstruction. This offers the most favorable result and thwarts the very high re-rupture rate seen with a non surgical approach.

The rehabilitation for partial tears of the Achilles tendon requires:

1. short-term immobilization to control the inflammatory phase.
2. progressive stretching and strengthening.
3. eventually task-specific rehabilitation which must include eccentric training to optimize tendon repair.

(Ref: Stanish WD, Rubinovich M, Curwin S. Eccentric Exercise in Chronic Tendinitis. Clinical Orthopaedics and Related Research, pgs. 65-68, 1985. Stanish WD, Lamb H, Curwin S. The Biomechanical Analysis of Chronic Patellar Tendinitis and Treatment with Eccentric Loading. Surgical and Arthroscopy of the Knee, 2nd Congress of the European Soceity; Eds. Muller/Hackenburch; Springer-Verlag Berlin Heidelberg 1988. Curwin S, Stanish WD. Tendinitis: Its Etiology and Treatment. The Collamore Press, D.C. health and Company, Lexington, MA.)

The Histochemistry of Tendon Repair
The healing Achilles tendon demonstrates both intrinsic and extrinsic mechanisms of repair with initially disorganized immature collagen. The "healed" Achilles tendon demonstrates realignment of collagen fibres which are similar in caliber, but do realign according to the lines of stress.

The Biomechanical Response of Tendon Repair
With a tendon injury - complete or partial - early control of inflammation followed by progressive stress to the tendon, is in order. Task specific challenges, emphasizing eccentric training, must follow.

Example No. 2: Twenty-three-year-old female with a complete rupture of the anterior cruciate disruption.

Facts Regarding Rehabilitation

1. Several factors will dictate ultimate outcome (associated osteoarthritis, meniscal tears, psychological factors).
2. The quality of the surgery will have a direct impact on the success of the rehabilitation.
3. The early program of rehabilitation must control the inflammatory component.
4. Maintenance of a normal range of motion of the knee joint is critical.
5. Re-establishing the normal proprioception must be included in the protocol.
6. The ultimate tensile strength of the anterior cruciate construct is approximately 50% of the normal strength. The morphology, biomechanics and histochemistry do not parallel the normal anterior cruciate ligament.

(Ref: Stanish WD, Lai A. New Concepts of Rehabilitation Following Anterior Cruciate Reconstruction. Clinics in Sports Medicine; Vol. 12:1, 25-58, January 1993. Shelbourne KD, et al. Current Concepts in ACL Rehabilitation. Orthopaedic Review, 19: 957, 1990. Tipton CM et al. Experimental Studies on the Influence of Physical Activity on Ligaments, Tendons and Joints: A brief review. Acta Medica Scandinavica, 1986; 711: 157-168. MacDonald PD et al. Proprioception in Anterior Cruciate Deficient and Reconstructed Knees. Am. J. of Sports Medicine, 1996; 24( C) 774-778. Irrgang JJ. Modern Trends in ACL Rehabilitation: Non-operative and Post-operative Management. Clinical Sports Medicine, 1993; 12(4), 797-813.)