Useful animal models for the research of osteoarthritis.

Osteoarthritis (OA) is a major cause of suffering for millions of people. Investigating the disease directly on humans may be challenging. The aim of the present study is to investigate the advantages and limitations of the animal models currently used in OA research. The animal models are divided into induced and spontaneous. Induced models are further subdivided into surgical and chemical models, according to the procedure used to induce OA. Surgical induction of OA is the most commonly used procedure, which alters the exerted strain on the joint and/or alter load bearing leading to instability of the joint and induction of OA. Chemical models are generated by intra-articular injection of modifying factors or by systemically administering noxious agents, such as quinolones. Spontaneous models include naturally occurring and genetic models. Naturally occurring OA is described in certain species, while genetic models are developed by gene manipulation. Overall, there is no single animal model that is ideal for studying degenerative OA. However, in the present review, an attempt is made to clarify the most appropriate use of each model.

Thermal microdebridement does not affect the time zero biomechanical properties of human patellar tendons.

BACKGROUND: Thermal microdebridement for the treatment of chronic tendinopathy has recently been introduced. The effect of thermal microdebridement on the biomechanical properties of human tendons, however, remains unknown. HYPOTHESIS: Thermal microdebridement does not affect the biomechanical properties of human patellar tendons in a cadaveric model at the time of initial treatment. STUDY DESIGN: Controlled laboratory study. METHODS: The central 15 mm of 12 matched, human (mean age, 71 years; 8 male, 4 female), fresh-frozen patellar tendons was divided into 3 equal 5-mm specimens. The treatment group (n = 12) underwent thermal microdebridement with a radiofrequency probe. A sham treatment group (n = 12) underwent insertion of a deactivated probe. The control group (n = 12) underwent no treatment. After treatment, each specimen was tested to failure in a servo-hydraulic materials testing machine at an elongation rate of 3 mm/s. One-way repeated measures analysis of variance was used to determine differences between groups. RESULTS: No significant difference in ultimate stress at failure, elastic modulus, strain energy density, or strain at maximum load was found between the groups. The ultimate stress at failure for the treatment, sham, and control groups was 61.0, 66.7, and 63.0 MPa, respectively (P = .653), and the strain at maximum load was 0.12, 0.11, and 0.09, respectively (P = .279). CONCLUSIONS: Thermal microdebridement does not affect the biomechanical properties of cadaveric human patellar tendons at the time of initial treatment. CLINICAL RELEVANCE: It may be safe to proceed with aggressive rehabilitation after thermal microdebridement of the patellar tendon. However, the results in this cadaveric model should be interpreted with caution. Additional studies using an in vivo model will be required to completely assess the effects of thermal microdebridement on the biomechanical properties of human patellar tendons.

Nandrolone decanoate and load increase remodeling and strength in human supraspinatus bioartificial tendons.

BACKGROUND: To date, no studies document the effect of anabolic steroids on rotator cuff tendons. STUDY DESIGN: Controlled laboratory study. HYPOTHESIS: Anabolic steroids enhance remodeling and improve the biomechanical properties of bioartificially engineered human supraspinatus tendons. METHODS: Bioartificial tendons were treated with either nandrolone decanoate (nonload, steroid, n = 18), loading (load, nonsteroid, n = 18), or both (load, steroid, n = 18). A control group received no treatment (nonload, nonsteroid [NLNS], n = 18). Bioartificial tendons' remodeling was assessed by daily scanning, cytoskeletal organization by staining, matrix metalloproteinase-3 levels by ELISA assay, and biomechanical properties by load-to-failure testing. RESULTS: The load, steroid group showed the greatest remodeling and the best organized actin cytoskeleton. Matrix metallo-proteinase-3 levels in the load, steroid group were greater than those of the nonload, nonsteroid group (P <.05). Ultimate stress and ultimate strain in the load, steroid group were greater than those of the nonload, nonsteroid and nonload, steroid groups (P <.05). The strain energy density in the load, steroid group was greater when compared to other groups (P <.05). CONCLUSIONS: Nandrolone decanoate and load acted synergistically to increase matrix remodeling and biomechanical properties of bioartificial tendons. CLINICAL RELEVANCE: Data suggest anabolic steroids may enhance production of bioartificial tendons and rotator cuff tendon healing in vitro. More research is necessary before such clinical use is recommended.

Chondroprotective effect of high-dose zoledronic acid: An experimental study in a rabbit model of osteoarthritis.

To address the need to impact the subchondral bone-articular cartilage interaction for the treatment of degenerative osteoarthritis (OA), bisphosphonates may be used as a means to inhibit the subchondral bone resorption. The purpose of the present study is to evaluate the chondroprotective effect of zoledronic acid (ZOL) in a model of OA. Eighteen adult male rabbits underwent an anterior cruciate ligament transection and were separated into two groups: ZOL group (n=10) received 0.6 mg/kg intravenous injection of ZOL on day 1, 15, and 29 and placebo group (n=8) received saline. The animals were euthanized at 8 weeks. Macroscopically, the ZOL group had significantly milder ulcerations, cartilage softening and fibrillation compared to the placebo group. Microscopically, morphology of the articular cartilage was better in the ZOL treated group compared with the placebo group, without complete disorganization in any section of the ZOL group. Furthermore, the chondrocytes in the ZOL treated group were mainly cloning, indicating cartilage repairing and regeneration process, while in the placebo group hypocellularity predominated. Additionally, subchondral necrosis was evident in some specimens of the placebo group. Zoledronic acid, in a high-dose regimen, proved to be chondroprotective in a well-established animal model of OA.

Sequential treatment with teriparatide and strontium ranelate in a postmenopausal woman with atypical femoral fractures after long-term bisphosphonate administration.

OBJECTIVE: Despite the existence of numerous case series, no evidenced-based medical management for atypical fractures associated with bisphosphonate (BP) treatment has been established. DESIGN: We report the outcome of teriparatide (TRP) administration followed by strontium ranelate (SR) in a woman with a complete and an incomplete contralateral atypical fracture of the femoral diaphysis (AFF) associated with BP treatment. The spontaneous complete AFF was managed with intramedullary nailing, discontinuation of BP and initiation TRP. RESULTS: Eleven months later, she suffered a contralateral incomplete AFF. At the completion of the TRP treatment, she had only slight discomfort in the femur with the incomplete AFF. BMD testing revealed increase of 7.61% at the lumbar spine (LS) and 0.8% at the hip. Following TRP, 1-year SR treatment resulted in further BMD increase of 9.2% at the LS and 1.4% in the hip, while she does not report any pain. Bone markers remain within the normal range. CONCLUSION: Our case indicates that sequential therapy with TRP and SR in cases of AFF might be a rational treatment option. However, there is a need for additional information concerning the effect of TRP and SR, given alone or sequentially, in these patients in order to incorporate these drugs into the management of AFF.

Isometric behavior of the reconstructed medial patellofemoral ligament using two different femoral pulleys: a cadaveric study.

BACKGROUND: Several techniques have been described for reconstructing the medial patellofemoral ligament (MPFL). However, the anatomy of the medial patellar retinaculum and the isometry of both intact and reconstructed MPFL remain controversial. The purpose of this study was to investigate the isometric behavior of the reconstructed MPFL when two different pulleys are used for the reconstruction. MATERIAL/METHODS: Eight anatomical knees were dissected and the medial patellar retinaculum and MPFL were studied. A pilot technique for the reconstruction of the MPFL using a semitendinosus autograft was developed. A "dynamic" femoral fixation was chosen which utilized two different pulleys: the medial intermuscular septum (MIS) at the adductor's tendon insertion and the posterior third of the medial collateral ligament (MCL). The isometric behavior of the reconstructed MPFL and the stability of both pulleys were investigated. RESULTS: The MPFL was a thickened, band-like condensation of the superficial MPR layer extending from the MFE to the medial border of the patella. The reconstructed MPFL demonstrated the most isometric behavior when the MCL was used as a pulley. The average difference in graft length during knee flexion from 0 degrees to 90 degrees when the MCL or MIS were used as a pulley was 1 mm and 4 mm, respectively. The MIS pulley was more stable but less isometric than the MCL pulley. CONCLUSIONS: "Dynamic" MPFL reconstruction with a semitendinosus tendon autograft can restore patellofemoral stability without excessive soft-tissue dissection or implantation of hardware at the medial epicondyle, which can lead to symptoms of its own.

Avulsion fractures of the tibial tuberosity in adolescent athletes treated by internal fixation and tension band wiring.

Avulsion of the tibial tuberosity is a rarely reported fracture. It is mainly considered as an athletic injury accounting for less than 3% of all epiphyseal lesions. In this study, we hypothesized that the use of tension band wiring as a supplement of the internal fixation for the avulsion fractures of the tibial tuberosity would lead the adolescent athletes to a more effective rehabilitation program and an earlier resumption of their previous activity level. Ten patients were treated in our department over a period of 11 years (1985-1995). Operative treatment was thought necessary for all our cases due to tibial tuberosity displacement. Open reduction and internal fixation in combination with tension band wiring was used. The result in all cases was that the reduction was maintained intact and the fracture united. The functional results were excellent, and all patients returned to their previous athletic activities. Our conclusion is that the combination of internal fixation and tension band wiring for avulsion fractures of the tibial tuberosity seems to be more effective and advantageous than conservative or other surgical methods. Avoiding the need of external support and allowing early joint motion, the method described prevents serious quadriceps atrophy, allowing the young athletes to return earlier to their previous sport activities.

Articular changes in experimentally induced patellar trauma.

Only a few studies have described the microscopic pathology of the articular cartilage after trauma. In the present animal study, we demonstrate the effect of trauma on the articular cartilage of the patella and determine the histological changes. Traumatic injury of the patella was experimentally induced in 45 white New Zealand rabbits aged 4 to 6 months old. The articular cartilage of the patella was observed after the sacrifice of the animals immediately and at days 1, 2, 4, 8, and 15 as well as at months 1, 2 and 3 after the traumatic injury. Macroscopic, light and electron microscopic findings showed progressive articular cartilage changes with failed effort of cartilage repair. Osteoarthritic-like degeneration of the articular cartilage was found in all specimens. According to this experimental study, trauma to the articular cartilage may progress to arthritis. The reversibility of cartilage damage or the progression to arthritis seem to be associated with many factors such as the intensity and frequency of the trauma, the mechanism of injury, the intrinsic remodeling of the cartilage matrix and the capability of the articular cartilage to regenerate.