Light microscopic and scanning electron microscopic retrieval analyses of implanted biomaterials retrieved from humans and experimental animals.

This paper reports analysis obtained from 200 implant cases retrieved from humans and submitted to the American Academy of Implant Dentistry Research Foundation, Medical College of Georgia implant retrieval center. The samples that were not decalcified were embedded in polymethylmethacrylate and examined with scanning electron microscopy and routine light, polarized, or Nomarski microscopy. Cases included both orthopedic and dental implants, as well as entire mandibles and portions of maxillae obtained at autopsy. A significant number of submitted implants had substantial amounts of adhered bone, which permitted evaluation of human bone remodeling to osseointegrated implants. These implants failed because of implant fracture. As was observed with animal studies, healthy bone supported these implants, with the bone containing an interdigitating canaliculi network that provided communication between interfacial osteocytes and osteocytes deeper within the remodeled osteonal and trabecular bone. Early dental implants containing a coating of beads showed a connective tissue interface, which corresponded to the bead surface of specific orthopedic implants that underwent some degree of micromovement. This is in contrast with the excellent response reported for successful contemporary beaded implants. Significant numbers of osseointegrated fractured hydroxyapatite (HA)-coated dental implants demonstrated the adequate serviceability of these implants before biomaterial fracture. In contrast, the HA coating was dissociated from retrieved orthopedic implants, leading to extensive cup loosening and case failure. This study, therefore, underscores the need for evaluation of failed human dental and orthopedic implants. Correlations can be drawn between human retrieval and experimental animal studies.

Cementless S-ROM femoral component: effect of stem length on stability after extended proximal femoral osteotomy.

The extended proximal femoral osteotomy is becoming increasingly popular in revision total hip replacement. Our study was done to determine the femoral stem length required for stable fixation of a cementless femoral component after an extended proximal femoral osteotomy. Three lengths of the S-ROM femoral stem were implanted in paired cadaver femora and tested under torsional and axial loads. The results indicate that the standard (160 mm) and long (215 mm) stems do not provide adequate torsional stability after a 160 mm extended proximal femoral osteotomy. The extra-long (255 to 315 mm) stems provided significantly greater stability, suggesting that the extended proximal femoral osteotomy may need to be bypassed by more than 2 cortical diameters, especially when a flexible stem such as the S-ROM is used.

Correlative experimental animal and human clinical retrieval evaluations of hydroxyapatite (HA)-coated and non-coated implants in orthopaedics and dentistry.

Retrieval analyses disclosed in vivo dissociation of HA in orthopaedic acetabular components, but excellent bone ingrowth into intact HA coatings on dental retrievals. Initial healing and the bone interface between HA-coated and non-coated implants in the posterior maxilla (Mx) and mandible (Md) was assessed in an animal model using light microscopy (LM), including confocal (CM) and Nomarski (NM) microscopy. Seventy-two implants (36 HA-coated; 36 non-coated) were placed into jaws of six dogs; half after extraction, half after 3 months healing. Animals were euthanized 3 months postimplantation. All implants osseointegrated; however, preliminary morphometry showed higher BCL for HA-coated (51%) than non-coated implants (44%) in the Mx (p < 0.05). BCL for HA-coated Md implants was not significantly higher (64%) than non-coated implants (62%). Bone closely apposed both implant types; however, LM suggested a more intimate association with HA coatings. Serial sections disclosed a reddish coating on the HA, possibly analogous to oral tissue proteoglycans, which was not visible with non-coated implants. This material was continuous with similar material coating endosteum, osteoid regions, and osteocyte (Os) lacunae close to the implant. An interdigitating canaliculi network allowed communication between interfacial Os and Os deeper within the bone. Data suggest HA offers enhanced initial bone fixation in the Mx, and that adequate bone exists for non-coated implant stability in the Md. No HA dissociation was seen with implants in the animal study, which was consistent with retrieved human HA dental implants.

Complications in total knee arthroplasty with and without surgical drainage.

The standard practice in total joint arthroplasty has included the use of postsurgical drains to minimize perioperative wound complications, particularly infection. This practice is not without cost and potential morbidity. Our recent cemented and cementless total knee arthroplasties (TKAs) have been done without the use of postoperative surgical drains and without any appreciable increase in wound complications. To confirm this, we retrospectively reviewed 227 consecutive TKAs, specifically evaluating perioperative wound complications. No statistical increase in perioperative complications in TKAs without drains was found. A lower percentage of complications was seen in the cementless population when compared with cemented or drained knees. We suggest that surgical drainage is not required in TKA, even when cementless fixation is used.

Retrieval analyses of implanted biomaterials: light microscopic and scanning electron microscopic analyses of implants retrieved from humans.

We report analyses obtained from 135 implant cases retrieved from humans and submitted to the American Academy of Implant Dentistry Research Foundation--Medical College of Georgia Implant Retrieval Center. The undecalcified samples were embedded in polymethyl-methacrylate and examined with scanning electron microscopy and with routine light via polarized or Nomarski microscopy. Cases included both orthopedic and dental implants as well as entire mandibles obtained at autopsy. Significant numbers of submitted implants had substantial amounts of adhered bone, which permitted evaluation of human bone remodeling to osseointegrated implants. These implants failed because of implant fracture. As has been observed in animal studies, an interdigitating canaliculi network provided communication between interfacial osteocytes and osteocytes deeper within the remodeled osteonal and trabecular bone. Significant numbers of osseointegrated fractured hydroxyapatite-coated dental implants demonstrated the adequate serviceability of these implants prior to biomaterial fracture. In contrast, the hydroxyapatite coating was dissociated from retrieved orthopedic implants, leading to extensive cup loosening and case failure. Caution is advised for the use of hydroxyapatite-coated acetabular implants. This study therefore underscores the need for evaluation of failed human dental and orthopedic implants. Correlations can be drawn between human retrieval and experimental animal studies.

Critical pathways: a means of managing the operating room.

Critical pathways help institutions in efficient and appropriate resource use to increase the quality of health care and minimize health care costs. However, many opportunities for pathway development and implementation are unexplored. This article delineates the development process for critical pathways and discusses the outcomes realized from use of the total joint pathway at the Medical College of Georgia, Augusta, GA.

The biologic tissue responses to uncoated and coated implanted biomaterials.

Ultrastructural examination of the morphology and morphometry of the bone supporting uncoated titanium and ceramic implants was assessed in an experimental animal model involving 120 implants placed into the mandibles of 30 adult mongrel dogs. Further, preliminary morphologic and morphometric observations of the bone supporting uncoated and hydroxylapatite-coated endosteal titanium implants was evaluated in a second investigation involving 72 implants placed into the mandibles and maxillae of 6 additional dogs. A densely mineralized collagen fiber matrix was observed directly interfacing with uncoated implants. The only material interposed between the implant and bone matrix was a 20- to 50-nm electron-dense material suggestive of a proteoglycan. Also seen in these same osseointegrated implants were narrow unmineralized zones interposed between the implant and bone matrix. In these zones of remodeling bone, numerous osteoblasts were observed interacting with the collagen fiber matrix. It was shown that a normal homeostasis of anabolic osteoblastic activity and catabolic osteoclastic activity resulted in bone remodeling and the resultant osseointegration of the implants. Hydroxylapatite-coated implants intimately interfaced with healthy bone. The mineralized matrix extended into the microporosity of the HA coating. This matrix contained viable osteocytes.

Ultrastructural analyses of the attachment (bonding) zone between bone and implanted biomaterials.

This report presents transmission electron and high voltage transmission electron microscopic observations of bone and associated remodeling tissues directly interfacing with endosteal dental implants. Undecalcified interfacial tissues were serially sectioned from mandibular samples encasing 60 implants placed into 30 dogs. Two-dimensional ultrastructural analyses and three-dimensional stereology showed that osteogenesis adjacent to dental implants is a dynamic interaction of osseous cells and a collagenous fiber matrix. This study showed that the interfacial bone consists of a mineralized collagen fiber matrix associated with an inorganic (hydroxylapatite) matrix. This study suggested that an unmineralized collagen fiber matrix initially is laid down directly at the implant surface, and that this matrix then is mineralized. Osteoblasts interacted with this matrix, eventually becoming encased within developing lacunae during the remodeling process. This process formed the cellular (osteocyte) aspects of the developed bone. Osteocyte processes extended through canaliculi directly to the implant surface. Apparently, these processes also were entrapped within canaliculi during the mineralization events. At times, these processes paralleled the implant surface. The bone-implant interfacial zone was primarily fibrillar (both mineralized and unmineralized) in morphology, with an electron-dense, ruthenium positive deposition. This electron-dense material was approximately 20 to 50 nanometers in thickness, and only this thin layer separated the remodeled mineralized bone from the implant.

In vivo evaluation of the biocompatibility of implanted biomaterials: morphology of the implant-tissue interactions.

Electron microscopic observations were made from tissues apposing titanium and ceramic root form and blade implants. The tissue was serially sectioned from the most coronal epithelium, through the gingival connective tissue, to the osseous support tissues, and directly to the most apical tissue support. Of the thousands of sections analyzed for each implant, 500 micrographs were routinely viewed for each of the implants analyzed by this study. Of the 120 total implants placed in 30 adult dogs, 60 were used for electron microscopy. Osseointegrated implants were often apposed by a mineralized matrix of collagenous fibers. The dense mineralized collagen matrix was often separated from the implant by only a ruthenium positive electron dense deposit 20 to 50 nanometers thick. Areas of the same implant were also apposed by an unmineralized collagen fiber stroma, which ranged in thickness, that contained osteoblasts. Interaction of the osteoblasts and the unmineralized collagen fibers resulted in the mineralization events of osteogenesis. Also apposing other areas of the same integrated implants were lacunar areas containing osteoclasts and vessels. These zones were similar to Howship's Lacunae. These results demonstrated that a normal homeostasis of catabolic osteoclastic activity and metabolic osteoblastic activity resulted in a dynamic implant-tissue interface. This biocompatible and dynamic support complex provides a construct for the long-term clinical serviceability of osseointegrated implants.

Total knee replacement in a patient with lupus anticoagulant.

The lupus anticoagulant is an acquired circulating anticoagulant that was first described in patients with systemic lupus erythematosus (SLE). This rare hematologic entity is seen in about 1% to 2% of the general population and about 10% to 35% of the patients with SLE. Although associated with a prolonged partial thromboplastin time (PTT), the lupus anticoagulant does not cause bleeding complications but may be associated with an increase in thromboembolic complications. This report is presented to alert orthopedic surgeons of the increased risk of thromboembolic disease with a paradoxically prolonged PTT in patients with the lupus anticoagulant.

Composite morphology of the bone and associated support-tissue interfaces to osseointegrated dental implants: TEM and HVEM analyses.

Correlated transmission electron and high-voltage electron microscopic analyses examined the undecalcified bone and associated support tissues of 60 endosseous titanium blade and titanium and ceramic root-form implants in dogs. The implants supported fixed partial dentures for up to 2 years. Data obtained from this investigation suggest that a range of tissues, both mineralized and unmineralized, support osseointegrated dental implants. This study examined the tissues apposing not just isolated aspects of the implant surface, but the entire length of the implant, and found that mineralized and unmineralized tissues existed concurrently. Much of the implant surface was apposed by mandibular bone, and both root-form and blade implants osseointegrated. The densely mineralized collagen fibril matrix was often separated from the implant by only a 20-nm to 50-nm electron-dense, ruthenium-positive deposit. High-voltage electron microscope stereology demonstrated that cellular processes extended directly to the implant from underlying osteocytes. In the same implants, areas containing an unmineralized collagen matrix interposed between the bone and implant surface were observed. In this region osteoblasts interacted with this matrix, and Howship's lacunae, containing vascular elements and osteoclasts, were also observed. The remodeling activities appear to be a homeostasis of catabolic activity (osteoclasts) and metabolic activity (osteoblasts). The apex of the implant was often apposed by a fibrofatty stroma. The support tissue response appears to be the result of the interrelations of osteoblasts, osteocytes, and osteoclasts in association with vascular elements. Therefore, the support tissue response to osseointegrated implants is a dynamic activity that involves the healthy interaction of these cells and tissues along the entire length of the implant.

Clinical use of a syndesmosis screw in stage IV pronation-external rotation ankle fractures.

The purpose of this study was to determine if biomechanical data obtained in studies on cadavers correlates with clinical results in the surgical treatment of stage IV pronation-external rotation (PER-IV) ankle fractures. We surgically treated 20 patients who sustained isolated PER-IV ankle injuries and followed 18 of the patients for an average of 2.5 years. Radiographs were evaluated using previously established methods, and clinical outcome was based on the criteria of Cedell. Eleven patients sustained a PER-IV injury with a medial malleolus fracture; 2 required a syndesmosis screw due to poor medial fixation. Good or excellent results were obtained in 90% of the patients in this group; the poor outcome of 1 patient was due to the development of reflex sympathetic dystrophy. Seven patients had a PER-IV injury with a deltoid ligament tear; because of widening of the syndesmosis, 1 patient required an early operation (within 1 week), and 2 patients required late operations (after 1 month). None of these patients should have required a syndesmosis screw based on biomechanical studies. Good or excellent results were obtained in 71% of the patients in this group. We conclude that the biomechanical data concerning placement of a syndesmosis screw in PER-IV ankle fractures does not correlate with in vivo outcome when a deltoid ligament injury occurs. A screw that stabilizes the distal tibiofibular syndesmosis should probably be placed in patients who sustain PER-IV injuries with deltoid ligament ruptures regardless of the level of the fibula fracture.

Acute gonococcal flexor tenosynovitis in an adolescent male with pharyngitis. A case report and literature review.

A 15-year-old boy had acute gonococcal flexor tenosynovitis of the middle finger associated with symptomatic gonococcal pharyngitis. The patient had a history of blunt trauma to the hand. The need for a careful history in any sexually active adolescent is emphasized. Acute flexor tenosynovitis may be the only manifestation of disseminated gonococcal infection.

The metal-backed patella. An invitation for failure?

Thirty-one cases of failed metal-backed patellar components requiring revision surgery are reviewed. Two modes of implant failure onset were noted. Within each group, delays in patient presentation and diagnosis of the failed component were encountered. The syndrome of the failed metal-backed patellar component is proposed. The authors conclude that: (1) more of these failures will be seen in the future; (2) this patient population needs appropriate counsel concerning the signs and symptoms of this syndrome as well as more frequent follow-up evaluations; (3) surgeons treating this complication should be prepared to revise all components; and (4) the use of metal-backed patellar components should be discontinued.

A quantitative assessment of degenerative changes acceptable in the unoperated compartments of knees undergoing unicompartmental replacement.

Thirty-five unicondylar knee arthroplasties were performed on 32 patients. In the unresurfaced compartments, degenerative cartilaginous changes were observed intraoperatively and recorded. The Outerbridge grading scale was used to assess the degree of arthritic change. In addition, the surface area involved was estimated. Grade III and limited grade IV changes in the unresurfaced tibiofemoral compartment and the patellofemoral joint did not preclude excellent results at a follow-up interval of 2 to 4 years.