Hyaline Cartilage Injuries: Options for Treatment

William D. Stanish, M.D., FRCS(C), FACS
Professor of Surgery, Dalhousie University
Director of Orthopaedic and Sports Medicine Clinic
Nova Scotia, CANADA

"The philosophies of one age have become the absurdities of the next."
-Sir William Osler-

Introduction
Historically, it was felt that cartilage was an inert tissue, which would be unresponsive to injury or insult. Progressive degeneration was felt to be inevitable. It is now realized that hyaline cartilage is metabolically active. With these intrinsic abilities, the clinical thrust is to maintain viability and integrity of the articular surface. (Ref: Buckwalter JA, Mankin HJ; Articular Cartilage: Part I & Part II. JBJS, Vol. 79A, 4, April 1997, pgs. 600-632.

Purpose of This Presentation
To examine the current techniques and strategies (both surgical and non surgical):

1. to halt the progression of osteoarthritis.
2. to promote the repair of degeneration of the articular surface.
3. to surgically reconstruct the joint surfaces which are afflicted with osteoarthritis.

With all of these medical interventions, it is vitally important to examine the reported

1. background and purported value of the treatment.
2. theoretical attributes of the technique.
3. basic science applied to the technique.
4. clinical experience and results.
5. an opinion as to the appropriate clinical applications of the specific technique.

Osteoarthritis: Degenerated Articular Cartilage

Scientific Facts

1. Articular cartilage is viable and is in a constant state of remodeling.
2. Hyaline cartilage has a mechanical threshold below 25 Newtons.
3. Articular cartilage can repair itself, to a certain degree, after injury.
4. The repair process of hyaline cartilage can be impaired if
   1. the patient is aged,
   2. the injury is extensive,
   3. the joint is maligned and/or unstable,
   4. there is pre-existing osteoarthrosis.
5. The repair process of injured articular cartilage is relatively florid if
   1. the patient is youthful,
   2. the injury is focal and shallow,
   3. the joint is aligned and stable, and
   4. the joint surface is virgin at the time of injury.

Clinical Caveats

1. The extent and degree of the osteoarthrosis does not necessarily parallel the degree of the symptomatology. (i.e., minor osteoarthrosis may produce severe pain, impaired range of motion, etc.)
2. Careful examination of the outcomes of any surgical of non surgical intervention in the treatment of osteoarthrosis is imperative. Controls? Intra and inter observer variation? Duration and quality of follow-up?
3. Must stand up to scientific criticism and analysis as postulated by Koch (1905) and others.

Non Surgical Interventions/Treatments

1. medications - NSAIDs, Glucosamine
2. injectables - Corticosteroids, Synvisc
3. braces
4. exercise/weight loss
5. activity modification

(Ref: Felson DT. The Epidemiology of Osteoarthritis: Prevalence and Risk Factors in Osteoarthritic Disorders. Am. Academy of Orthopaedic Surgeons, 1995; pgs 13-24. Buckwalter JA, Lane NE. Athletics and Osteoarthritis, Am. Journal of Sports Medicine, Vol 25:6, 1997, pgs. 873-881.)

Surgical Techniques to Halt/Retard Progression of Degenerative Osteoarthritis

1. Osteotomy
   
   Theory: To correct skeletal malalignment in order to load to more normal articular cartilage.
   
   Basic Science: Studies at 2 years after tibial osteotomy have demonstrated development of fibrocartilage on the medial compartment. (Ref: Bergenudd H, et al. The Articular Cartilage After Osteotomy for Medical Gonarthrosis: Biopsies after 2 years in 19 cases. ACTA Orthop. Scandinavica, 63: 413-416, 1992)
   
   Clinical Science: The improvement of symptomatology seems to deteriorate over time. (Ref. Coventry MB, et al. Proximal Tibial Osteotomy: A critical long-term study of 87 cases. JBJS, 75A: 196-201, Feb. 1993)
   
   Opinion: The malalignment must be corrected accurately in order to yield results that are satisfactory. Osteotomy may be employed in conjunction with joint reconstruction (transplantation of replacement).
   
2. Joint Distraction
   The basic concept is to provide distraction or decompression of the degenerated articular cartilage.
   
   Theory: That decreased joint forces, combined with motion, will potentially facilitate fibrocartilage formation.
   
   Basic Science/Clinical Science: Studies have reported favourable results in preventing progression of osteoarthrosis. (Ref: Aldegheri R, et al. Articulated Distraction of the Hip: Conservative surgery for arthritis in young patients. Clin. Orthop. 301:94-101, 1994)
   
   Opinion: Currently this technique is impractical and the clinical results are somewhat questionable. (Ref: Buckwalter JA. Joint Distraction for Osteoarthritis. J. Lancet, 347: 279- 280, 1996)

Techniques to Restore Degenerated Articular Cartilage/Osteoarthrosis

1. Joint Debridement and Penetration of the Subchondral Bone
   
   Theory: To facilitate the repair process with repopulating of the articular surface with undifferentiated mesenchymal stem cells.
   
   Basic Science: A rabbit model of fibrocartilage, formed after drilling of the Articular surface. (Ref: Fraenkel SR, et al. A Comparison of Abrasion Burr Arthroplasty and Subchondral Drilling in the Treatment of Full Thickness Cartilage Lesions in the Rabbit. The transactions of the Orthopaedic Research Society, 19: 483, 1994.)
   
   Clinical Science: The reported results range from "miracles" in which they demonstrate restoration of joint surfaces to clinical results that demonstrated rather poor long-term relief of discomfort. (Ref: Johnson LL. Arthroscopic Abrasion Arthroplasty in Operative Arthroscopy. Raven Press, pgs. 427-446, 1996. Buckwalter JA. Current Concepts Review Operative Treatment of Osteoarthrosis: Current Practice and Future Development. JBJS 76A: 1405-1418, Sept. 1994)
   
   Opinion: The clinical results are rather unpredictable, particularly in cases with associated malalignment.
   
2. Interposition Perichondral/Periosteal Grafts
   
   Theory: To function as a joint buffer and introduce a new cohort of Mesenchymal stem cells.
   
   Basic Science: A rabbit model, with articular defects, demonstrated new cartilage formation after soft tissue grafting and CPM. (Ref: Salter RB. The Biological Effect of Continuous Passive Motion on the Healing of Full Thickness Defects in Articular Cartilage. An experimental Investigation in the rabbit. JBJS, 62A: 1232-1251, Dec. 1980)
   
   Clinical Science: Basically restricted to studies in the interphalangeal joints. The results were adversely effected by age. (Ref: Scradge H, et al. Perichondral Resurfacing Arthroplasty in the Hand. J. of Hand Surg., 9A:880-886, 1984)
   
   Opinion: Soft tissue grafts are a valuable source of undifferentiated mesenchymal cells. This technique is reserved ideally for the non-weight bearing surface in the younger patient, with a small defect in the articular surface.
   
3. Autologous Chondryte Transplantation
   
   Theory: To harvest undifferentiated mesenchymal cells from the host, with chondrocytes - grown in tissue culture for approximately 14 to 21 days - and then re-implanted in defects in the articular surface.
   
   Basic Science: Animal experimentation is very promising with autologous chondrocyte transplantation proving effective with and without carbon fibres scaffolding. (Ref: Wakitani S., et al. Mesenchymal Stem Cell Based Repair of Large Articular Cartilage and Bone Defect. Transactions of the Orthopaedic Research Society, 19: 481, 1994. Wakitani S, et al. Repair of Rabbit Articular Surfaces with Allograft Chondrocytes Imbedded in Collagen Gell. JBJS 71B: 74-80, 1989)
   
   Clinical Science: In some cases autologous chondrocyte transplantation is able to promote cartilage repair in vivo. (Ref: Brittberg M, et al. Treatment of Deep Cartilage Defects in the Knee with Autologous Chondrocyte Transplantation. New England J. of Med., 331: 889-895, 1994)
   
   Opinion: Widespread application of this technique should be discouraged until trials are complete. These trials must be carefully constructed and scrutinized as commercial forces prevail. (Ref: Jackson DW, Simon TM. Chondrocyte Transplatation: Current Concepts. Arthroscopy: The Journal of Arthroscopic and Related Surgery, Vol. 12:6, 732-738, 1996.)
   
   Addendum: Artificial Matrices
   There are several techniques available by which carrying agents/materials are deployed to transplant cells, growth factors, etc. These matrices vary in their biological behaviour and thus their abilities to provoke synovitis. (Ref: Messner K, Gilquist J. Synthetic Implants for the Repair of Osteochondral defects of the Medial Femoral Condyle: A biomechanical and histological evaluation in the rabbit knee. Biomaterials 14: 513-521, 1993)
   
4. Transplantation of Articular Cartilage
   
   Autograft
   
   Theory: To harvest sized osteochondral grafts from non weight bearing surfaces and re-implant them to more vital areas of degenerate or injured articular surface.
   
   Basic Science/Clinical Science: Several studies with long-term follow-up have demonstrated the merits of this technique. (Ref: Outerbridge HK, et al. The Use of a Lateral Patellar Autogenous Graft for the Repair of Large Osteochondral Defects in the Knee. JBJS 77A: 65-72, January 1995)
   
   Opinion: Autologous articular surface transplantation has considerable merit and application. The technique of fixation is critical and the value of continuous passive motion, with altered weight bearing, must be emphasized.
   
   Allograft
   
   Theory: In contrast to autograft, there is less morbidity from the donor site and improved ability to shape and tailor the graft.
   
   Basic Science/Clinical Science: Some authors report clinical results comparable to those employing autogenous cartilage transplantation. (Ref: Flynn JM, et al. Osteoarticular Allografts to Treat Femoral Distal Osteonecrosis. Clinical Orthopedics; 303: 38-43, 1994)
   
   Opinion: Be careful before embracing the technique of transplantation of articular cartilage allograft, particularly in those cases where there is a large defect, or where, indeed, the joint is malaligned. In those cases failure is predictable if a concomitant osteotomy is not carried out.

Conclusion
There is potential to encourage the repair of the injured or degenerative articular cartilage. The quality of the repair will depend on several factors, including the extent of the osteoarthritis, the morphology and age of the patient, as well as the functional expectations for the "new tissue". Based on our current information the "new tissue" will never be normal articular cartilage.