Background: Osteoarthritis results in the loss of cartilage in the synovial joint. The severity has been classified, with the complete loss of articular cartilage called the Outerbridge IV lesion.
It is known that reduction of forces across a joint or portion of a synovial joint having an Outerbridge IV condition will result in the regrowth of cartilage tissue in the previously damaged area.
Review of Medical Literature: This is documented in the medical literature. In the knee joint, when cartilage is lost in one compartment or the other, the loss of this substance results in an abnormal angulation of the limb at the knee joint. The condition may be bowleg or knock-knee. The former when the inner knee compartment loses its cartilage and the later when the outer compartment loses its articular cartilage.
Cutting of the bone in the upper femur near the hip was a method used years ago to shift the weight on the ball part of the hip socket so that the area might heal the joint. This did happen and has been reported numerous times in the medical literature. The following is one such article.
D'Souza SR, Sadiz S, New AMR, Northmore-Ball MD.
Proximal Femoral Osteotomy as the Primary Operation for Young Adults Who Have Osteoarthritis of the Hip.
J Bone Joint Surg 80:1428-38 (1998).
The first photo is Pre OP the second photo is 6 years Post OP
One of the treatments is to perform a bone cutting operation to straighten the leg. This was first popularized by Mark Coventry of the Mayo Clinic.
Upper Tibial Osteotomy for Degenerative Arthritis
J Bone Joint Surg 1985;67A;1136-1140.
Pre and Post OP x-rays showing wider medial joint space
Subsequent reports on this surgical procedure included inspection of the degenerative joint before and after the operation. It was observed that areas completely denuded of articular cartilage had subsequent regrowth of cartilage following the operation that unloaded the forces across that compartment of the knee joint.
Koshino T, Wada S, Ara Y, Saito T.
Regeneration of degenerated articular cartilage after high tibial valgus osteotomy for medial compartment osteoarthritis of the knee
Kischino's before and after photographs showing cartilage healing following unloading of the knee joint by osteotomy
T.Kanamiya, M.Naito, M.Hara, I.Yoshimura et al
The influences of biomechanical factors on cartilage regeneration after high tibial osteotomy for knees with medial compartment osteoarthritis.
Arthroscopy: The Journal of Arthroscopic & Related Surgery, Volume 18, Issue 7, Pages 725-729
Kanamiya's before and after arthroscopic illustrations of cartilage healing following unloading by osteotomy
A similar result has been reported following two patients who spontaneously unloaded the severe arthritic hip following a pain relieving total hip replacement on the opposite side. In this report of two cases, the patients had bilateral severe hip arthritis. They submitted to a total hip operation on one side with plans for the other side to be treated within a few months. Both patients subsequently refused the planned surgery as the previously "bad" hip was better. Both patients were followed for 7 and 11 years respectively. The results were that the previously arthritic hip with bone on bone grew a new joint space. Equally as amazing, the bone about the hips, which was architecturally destroyed, changed in shape similar to a normal hip. This change is known as Wolff's law in medicine.
Guyton GP, Brand RA
Apparent spontaneous joint restoration in hip osteoarthritis.
Clin Ortho Rel Res 2002, #404;pp.302-307.
Guyton and Brand's Case #1
Shows regeneration of the hip joint
Case #2 shows marked increase in joint space and remodeling of the bone following opposite hip surgery that allowed unloading of this hip
The explanation for such a dramatic change in biology was not even speculated in any of the aforementioned reports.
The basis for the repair is now known. The reduction in pressure of some amount results in opportunity for cartilaginous aggregates normally found on the Outerbridge IV lesions to proliferate and regenerate the previously damaged joint surface.
The nature of the cartilaginous aggregates were first observed in 1979 and reported by Johnson.
Johnson, LL. Arthroscopic Surgery; Principles and Practice. C. V. Mosby. St. Louis, MO. USA. 1986
Microscopic photograph of cartilaginous aggregates (stained red) at the surface in the most severe stage of osteoarthritis when all the cartilage is worn off
A more in depth study on the cartilaginous aggregates was reported. They were seen to, histologically, have many of the properties of normal cartilage. They had histochemical staining showing type II collagen and the lubricin molecule on the surface. There was cellular orientated architecture of both fibrocartilage and articular cartilage.
Zhang D, Johnson LL, Hsu HP, Spector M.
Cartilaginous deposits in subchondral bone in regions of exposed bone in osteoarthritis of the human knee: Histomorphometric study of PRG4 distribution in osteoarthritic cartilage
Journal of Orthopaedic Research
Volume 25, Issue 7, Date: July 2007: 873-883
Further evidence of such repair phenomena was reported in the hip by Milgram. He showed that 535 severe arthritic hips removed at surgery had cartilaginous tuffs. Some even coalesced to cover the joint surface.
Milgram JW: Morphologic alterations of the subchondral bone in advanced degenerative arthritis. Clin Orthop 173:293-312, 1983.
Photographs of the gross pathology on the left showing cartilaginous aggregates all over the surface. The photograph on the right is the microscopic view showing the cartilaginous budding on the surface. (Milgram)
The potential for repair of the Outerbridge IV lesion when unloaded as following high tibial osteotomy is supported by the publication by Wakabayashi et al.
Wakabayashi S, Akizuki S, Takizawa T, Yasukawa Y. A Comparison of the Healing Potential of Fibrillated Cartilage Versus Eburnated Bone in Osteoarthritic Knees After High Tibial Osteotomy: An Arthroscopic Study With 1-Year Follow-up. Arthroscopy 18 (3) 2002: pp272-278
These authors showed repair of the Outerbridge lesion on both the femoral and the tibial side of the joint at one year. At one year, the second look arthroscopy showed 62% of the previously surfaces of exposed bone to be covered with fibrocartilage.
B: 1 year later
Interestingly, the patients with intact but fibrillated cartilage did NOT show evidence of repair. This report supports the premise of the cartilaginous aggregates being the source of repair when a joint with eburnated bone is unloaded as with osteotomy.
Lanny L Johnson, Christopher Verioti, Jonathan Gelber, Myron Spector, Darryl D'Lima, Andrew Pittsley. The pathology of the end-stage osteoarthritic lesion of the knee: Potential role in cartilage repair. The Knee. 8 (6) 2010: 402-406.
This publication shows the cartilagenous aggregates near and on the surface as a potential for cartilage regeneration. In addition, surface pits have been reported for the first time. These pits may serve as a "home" for various therapeutics.
Summary: It is clear from the medical literature that reduction of abnormally high forces across the most severe arthritic joint will result in repair of the joint by regrowth of articular cartilage. It is likely the normal healing process is based upon the proliferation of the cartilaginous aggregates present on the surface of the most severe arthritic condition.
Since it has been shown by direct evidence in studies at Scripps Institute that forces across one compartment of the knee may be reduced up to 50% in activities of daily living, it is reasonable to hypothesize that a similar repair would occur as after other methods of unloading an effected joint. This hypothesis is presently being confirmed.