Tribological changes in the articular cartilage of a human femoral head with avascular necrosis.
The present study evaluated the tribological properties of the articular cartilage surface of the human femoral head with postcollapse stage avascular necrosis (AVN) using atomic force microscopy. The cartilage surface in the postcollapse stage AVN of the femoral head was reported to resemble those of disuse conditions, which suggests that the damage could be reversible and offers the possibilities of success of head-sparing surgeries. By comparing the tribological properties of articular cartilage in AVN with that of osteoarthritis, the authors intended to understand the cartilage degeneration mechanism and reversibility of AVN. Human femoral heads with AVN were explanted from the hip replacement surgery of four patients (60-83 years old). Nine cylindrical cartilage samples (diameter, 5 mm and height, 0.5 mm) were sectioned from the weight-bearing areas of the femoral head with AVN, and the cartilage surface was classified according to the Outerbridge Classification System (AVN0, normal; AVN1, softening and swelling; and AVN2, partial thickness defect and fissuring). Tribological properties including surface roughness and frictional coefficients and histochemistry including Safranin O and lubricin staining were compared among the three groups. The mean surface roughness Rq values of AVN cartilage increased significantly with increasing Outerbridge stages: Rq = 137 ± 26 nm in AVN0, Rq = 274 ± 49 nm in AVN1, and Rq = 452 ± 77 nm in AVN2. Significant differences in Rq were observed among different Outerbridge stages in all cases (p < 0.0001). The frictional coefficients (μ) also increased with increasing Outerbridge stages. The frictional coefficient values were μ = 0.115 ± 0.034 in AVN0, μ = 0.143 ± 0.025 in AVN1, and μ = 0.171 ± 0.039 in AVN2. Similarly to the statistical analysis of surface roughness, significant statistical differences were detected between different Outerbridge stages in all cases (p < 0.05). Both surface roughness and frictional coefficient of cartilage, which were linearly correlated, increased with increasing Outerbridge stages in postcollapse AVN. The underlying mechanism of these results can be related to proteoglycan loss within the articular cartilage that is also observed in osteoarthritis. With regard to the tribological properties, the cartilage degeneration mechanism in AVN was similar to that of osteoarthritis without reversibility.
Institute for Skeletal Aging and Orthopedic Surgery, Hallym University-Chuncheon Sacred Heart Hospital, Chuncheon 200-704, South Korea.
Eun-Min
EM
Seo
Institute for Skeletal Aging and Orthopedic Surgery, Hallym University-Chuncheon Sacred Heart Hospital, Chuncheon 200-704, South Korea.
Suman K
SK
Shrestha
Mechanical Engineering Department, Industrial University of Ho Chi Minh City, Ho Chi Minh 70000, Vietnam.
Cong-Truyen
CT
Duong
Institute for Skeletal Aging and Orthopedic Surgery, Hallym University-Chuncheon Sacred Heart Hospital, Chuncheon 200-704, South Korea.
Ashish Ranjan
AR
Sharma
Institute for Skeletal Aging and Orthopedic Surgery, Hallym University-Chuncheon Sacred Heart Hospital, Chuncheon 200-704, South Korea.
Tae-Woo
TW
Kim
Institute for Skeletal Aging and Orthopedic Surgery, Hallym University-Chuncheon Sacred Heart Hospital, Chuncheon 200-704, South Korea.
Ayyappan
A
Vijayachandra
Department of Engineering Science, University of Oxford, Oxford OX1 2JD, United Kingdom.
Mark S
MS
Thompson
Institute for Skeletal Aging and Orthopedic Surgery, Hallym University-Chuncheon Sacred Heart Hospital, Chuncheon 200-704, South Korea.
Myung Guk
MG
Cho
Department of Urology, University of Ulsan, College of Medicine, Ulsan 682-714, South Korea.
Sungchan
S
Park
School of Mechanical Engineering, Pusan National University, Busan 609-735, South Korea.
Kwanghoon
K
Kim
School of Mechanical Engineering, Pusan National University, Busan 609-735, South Korea.
Seonghun
S
Park
Institute for Skeletal Aging and Orthopedic Surgery, Hallym University-Chuncheon Sacred Heart Hospital, Chuncheon 200-704, South Korea.
Sang-Soo
SS
Lee
D000368:Aged; D000369:Aged, 80 and over; D002358:Cartilage, Articular / Q000473:pathology*; D005269:Femur / Q000473:pathology*; D005271:Femur Head Necrosis / Q000473:pathology*; D006651:Histocytochemistry; D006801:Humans; D008853:Microscopy; D018625:Microscopy, Atomic Force; D008875:Middle Aged; D013499:Surface Properties