Rehabilitative strategies following hand fractures.

The importance of rehabilitation in the management of hand fractures cannot be overstated. The breadth of rehabilitative strategies ranges from heat and range-of-motion exercises to more complex splinting and tendon gliding modalities. The goals, however, are clear: control pain; limit soft tissue swelling; provide support for fracture healing; restore motion, strength, and function; and enable the return to work and daily activities.

Symptoms associated with compartmental radiographic disease in hip arthroplasty patients.

We compared symptoms to radiographic disease in the medial (less weight bearing) and axial and superolateral (greater weight bearing) compartments in total hip arthroplasty patients. Western Ontario and McMaster Universities Osteoarthritis Index scores (0 [best] to 100 [worst]) were better for patients with more medial than axial radiographic disease for pain (41 vs 53; P =.002), stiffness (43 vs 56; P =.003), and function (49 vs 58; P =.03). Similarly, patients with more medial than superolateral disease had fewer symptoms. Patients with disease principally in the less weight-bearing medial compartment had milder symptoms than their radiographs suggested. Patients with disease principally in the greater weight-bearing axial and superolateral compartments had more severe symptoms than their radiographs suggested. The association between symptoms and radiographic disease depended on which compartment of the hip was most affected.

Two-year radiostereometric analysis evaluation of femoral head penetration in a challenging population of young total hip arthroplasty patients.

This prospective, randomized protocol evaluated femoral head penetration after total hip arthroplasty in a young population. Forty-five patients randomly received either a cross-linked or conventional ultrahigh-molecular-weight polyethylene (UHMWPE) liner in a noncemented hemispheric cup (Trilogy, Zimmer, Warsaw, Ind) with a 28-mm femoral head. Radiostereometric analysis film pairs, Harris hip, UCLA, SF-12, and Western Ontario and McMaster Universities scores were obtained through 2 years. Median femoral head penetration was less among cross-linked compared to conventional liners as follows: 0.06 mm (0.04-0.08 mm) vs 0.08 mm (0.02-0.19 mm) at 6 months, 0.07 mm (-0.14 to 0.16 mm) vs 0.11 mm (0.01-0.27 mm) at 1 year, and 0.065 mm (-0.04 to 0.193 mm) vs 0.169 mm (0.09-0.22 mm) at 2 years. Clinical outcomes were similar between the groups. Highly cross-linked UHMWPE demonstrated 55% less femoral head penetration compared to conventional polyethylene at 2 years. Despite improvements in the manufacturing process and sterilization of conventional UHMWPE, the femoral head penetration rate is unchanged from historical standards.

Immobilization modulates macrophage accumulation in tendon-bone healing.

Tendon-to-bone healing occurs by formation of a fibrous, scar tissue interface rather than regeneration of a normal insertion. Because inflammatory cells such as macrophages lead to formation of fibrous scar tissue, we hypothesized immobilization would allow resolution of acute inflammation and result in improved tendon-bone healing. We reconstructed the ACL of 60 Sprague-Dawley rats using a tendon autograft. An external fixation device was used to immobilize the surgically treated knee in 30 rats. We evaluated tendon-bone interface width, collagen fiber continuity, and new osteoid formation histologically. Immunohistochemistry was used to localize ED1+ and ED2+ macrophages at the tendon-bone interface at 2 and 4 weeks. Biomechanical testing was performed at 4 weeks. Interface width was smaller and collagen fiber continuity was greater in the immobilized group. Immobilized animals exhibited fewer ED1+ macrophages at the healing interface at 2 and 4 weeks. In contrast, there were more ED2+ macrophages at the interface in the immobilized group at 2 weeks. Failure load and stiffness were similar between groups at 4 weeks. The data suggest early immobilization diminishes macrophage accumulation and may allow improved tendon-bone integration.

The role of macrophages in early healing of a tendon graft in a bone tunnel.

BACKGROUND: Macrophages accumulate following tendon-to-bone repair and may contribute to the formation of a scar-tissue interface rather than to the reformation of a normal insertion site. We hypothesized that macrophage depletion may lead to improved insertion site regeneration, in a form of "scar-less" healing rather than reactive scar-tissue formation. METHODS: One hundred and ninety-two Sprague-Dawley rats underwent anterior cruciate ligament reconstruction with use of a flexor tendon autograft and were divided into a control group (ninety-six rats) and a liposomal clodronate-injected group (ninety-six rats). Clodronate is a bisphosphonate that selectively induces macrophage apoptosis. Animals in the liposomal clodronate group received weekly intraperitoneal injections of liposomal clodronate (1.33 mL/100 g of body weight). Rats were killed at serial time points from three to forty-two days. Immunostaining identified macrophages and transforming growth factor-beta (TGF-beta) at the tendon-bone interface. Fibrous interface width, osteoid formation, and collagen fiber continuity were evaluated with use of histomorphometry. Serial fluorochrome labeling was used to measure mineral apposition rate. Additional rats were killed for biomechanical testing at seven, fourteen, twenty-eight, and forty-two days. RESULTS: Liposomal clodronate significantly decreased macrophages and TGF-beta accumulation at the tendon-bone interface (p < 0.05). Specimens from rats that received liposomal clodronate exhibited a significantly narrower fibrous tissue interface between tendon and bone at all time points compared with specimens from controls (p < 0.05). In specimens from the liposomal clodronate group, healing proceeded at an accelerated rate, characterized by enhanced collagen fiber continuity and a greater degree of interface remodeling between tendon and bone. There were significant increases in osteoid formation (p < 0.05) and mineral apposition rates (p < 0.05) among experimental specimens. At forty-two days, the specimens from the liposomal clodronate group had significantly greater increases than the control specimens with respect to load to failure (mean and standard deviation, 13.5 +/- 4.2 N and 9.7 +/- 3.9 N, respectively; p < 0.05) and stiffness (mean, 11.5 +/- 5.0 N/mm and 7.5 +/- 3.2 N/mm; p < 0.05). CONCLUSIONS: Macrophage depletion following anterior cruciate ligament reconstruction resulted in significantly improved morphologic and biomechanical properties at the healing tendon-bone interface, which we hypothesize are due to diminished macrophage-induced TGF-beta production.

The effect of osteoclastic activity on tendon-to-bone healing: an experimental study in rabbits.

BACKGROUND: Healing of a tendon graft in a bone tunnel depends on bone ingrowth into the interface between tendon and bone. Excessive osteoclastic activity may contribute to bone resorption, tunnel widening, and impaired healing. We hypothesized that inhibition of osteoclastic activity by osteoprotegerin (OPG) would increase bone formation around a tendon graft in anterior cruciate ligament reconstruction in a rabbit model, while increased osteoclastic activity due to the application of receptor activator of nuclear factor-kappa B ligand (RANKL) would impair bone ingrowth. METHODS: Sixty skeletally mature, male New Zealand White rabbits underwent bilateral anterior cruciate ligament reconstruction. OPG (100 microg per tunnel) or RANKL (10 microg per tunnel) was delivered to the tendon-bone interface with use of a synthetic calcium phosphate carrier vehicle. Twenty animals were killed at two, four, and eight weeks after surgery. Two rabbits from each group were prepared for histological evaluation, and the other rabbits were used for biomechanical testing. RESULTS: A significantly greater amount of bone surrounded the tendon at the healing tendon-bone interface in the OPG-treated limbs compared with the controls and the RANKL-treated limbs at all time-points (p < 0.05). There were significantly fewer osteoclasts in the OPG-treated limbs compared with the controls and the RANKL-treated limbs (p < 0.05). The average tunnel area in the OPG group was significantly smaller than that in the RANKL group (p = 0.003 at two weeks and p = 0.004 at four weeks). The femur-anterior cruciate ligament-tibia complex of the OPG-treated limbs had significantly increased stiffness compared with RANKL-treated limbs at eight weeks (p = 0.04). CONCLUSIONS: Osteoprotegerin significantly improves bone formation around the grafted tendon and improves the stiffness at the healing tendon-bone junction in a rabbit model.

Bone morphogenetic proteins-signaling plays a role in tendon-to-bone healing: a study of rhBMP-2 and noggin.

BACKGROUND: Successful anterior cruciate ligament reconstruction requires secure healing between tendon and bone. HYPOTHESIS: Bone morphogenetic protein-signaling plays an important role in tendon-to-bone healing. rhBMP-2, a powerful osteoinductive agent, can improve tendon-bone interdigitation. STUDY DESIGN: Controlled laboratory study. METHODS: The study was designed in 2 phases: Phase I consisted of a dose-response study where 21 New Zealand White rabbits underwent bilateral anterior cruciate ligament reconstructions. Rabbits received either rhBMP-2 (11.5, 50, or 115 microg) or noggin (10, 15, 30, or 100 ng) (a potent bone morphogenetic proteins inhibitor) delivered in an injectable calcium phosphate matrix. Animals were sacrificed at 2 weeks and histomorphometric analyses were performed. In phase II, 60 rabbits underwent bilateral anterior cruciate ligament reconstructions and were assigned to 3 groups: rhBMP-2 (115 microg), noggin (30 ng) in a calcium phosphate carrier, and calcium phosphate carrier alone. Animals were sacrificed at 2, 4, and 8 weeks and histomorphometric and biomechanical analyses were performed. RESULTS: rhBMP-2 treatment led to a significant increase in the width of new bone formation at the tendon-bone interface in a dose-dependent fashion (0.24-0.35 mm vs 0.13-0.16 mm in controls). All dosages of noggin inhibited new bone formation (0.06-0.1 mm vs 0.15-0.16 mm in controls); however, there was no dose-dependent effect in the concentrations studied. In the phase II study, rhBMP-2 resulted in a significant increase in new bone formation (81%, 89%, and 113%) at increasing time periods compared with controls. Tunnel diameters in the rhBMP-2 group were significantly smaller (15%-45%) than in the carrier group. The negative effect of noggin was not sustained, as new bone formation increased with time. The rhBMP-2 group demonstrated significantly increased stiffness at 8 weeks, while there was no significant difference in ultimate tensile load when compared with the other 2 groups. CONCLUSION: rhBMP-2 demonstrated a strong, positive dose-dependent effect on osteointegration at the tendon-bone junction. In contrast, noggin decreased osteointegration. No tunnel widening was detected with rhBMP-2 using the calcium phosphate carrier. CLINICAL RELEVANCE: Further studies are needed to investigate the potential clinical application of enhancing healing and decreasing recovery time using bone morphogenetic proteins in soft tissue ligament reconstruction.