The management of bone loss in revision total knee arthroplasty: rebuild, reinforce, and augment.

The treatment of bone loss in revision total knee arthroplasty has evolved over the past decade. While the management of small to moderate sized defects has demonstrated good results with a variety of traditional techniques (cement and screws, small metal augments, impaction bone grafting or modular stems), the treatment of severe defects continues to be problematic. The use of a structural allograft has declined in recent years due to an increased failure rate with long-term follow-up and with the introduction of highly porous metal augments that emphasise biological metaphyseal fixation. Recently published mid-term results on the use of tantalum cones in patients with severe bone loss has reaffirmed the success of this treatment strategy.

Nanocrystalline hydroxyapatite-based material already contributes to implant stability after 3 months: a clinical and radiologic 3-year follow-up investigation.

The present study reports on a 3-year clinical and radiologic follow-up investigation of dental implants placed 3 and 6 months after sinus augmentation in 14 patients. Augmentation was performed with a synthetic bone substitute material composed of nanocrystalline hydroxyapatite. The aim of the study was to determine how the integration period of the bone substitute material, that is, 3 months or 6 months, influences implant integration within the patient's upper jaw. Therefore, the following clinical and radiologic parameters were investigated: implant being in situ; Periotest value; and presence of peri-implant osteolysis, bleeding on probing, plaque, and soft tissue recession around the implants. At the follow-up investigation 3 years after placement, 23 of 24 implants were in situ and suitable for prosthetic rehabilitation. No implants in either study group were mobile or showed peri-implant osteolysis. Only a few implants showed plaque or soft tissue variations. Within its limits, the present study showed comparable clinical performance of dental implants placed 3 months after sinus floor augmentation to implants placed 6 months after augmentation. The results of all investigated parameters were in accordance with results found in the literature. It can be concluded that augmentation with the applied synthetic bone substitute material already forms a sufficient implantation bed 3 months after augmentation, which enables long-term, stable, implant-retained restoration. These findings might contribute to a reduced healing time after augmentation, which would be favorable for patients and clinicians.

Computed tomography vs. digital radiography assessment for detection of osteolysis in asymptomatic patients with uncemented cups: a proposal for a new classification system based on computer tomography.

Digital radiographic images in the anterior-posterior and lateral view have been gold standard for evaluation of peri-acetabular osteolysis for patients with an uncemented hip replacement. We compared digital radiographic images and computer tomography in detection of peri-acetabular osteolysis and devised a classification system based on computer tomography. Digital radiographs were compared with computer tomography on 206 hips, with a mean follow up 10 years after surgery. The patients had no clinical signs of osteolysis and none were planned for revision surgery. On digital radiographs, 192 cases had no osteolysis and only 14 cases had osteolysis. When using computer tomography there were 184 cases showing small or large osteolysis and only 22 patients had no osteolysis. A classification system for peri-acetabular osteolysis is proposed based on computer tomography that is easy to use on standard follow up evaluation.

Periprosthetic aseptic osteolysis in total ankle replacement: cause and management.

Osteolysis is the loss of bone secondary to a pathologic process and remains the most common cause of failure of total ankle replacement. Friction at the bearing surface results in the generation of abraded wear debris of polyethylene. These activate a biologic cascade that may result in significant bone loss and subsequent loss of fixation of the prosthesis. Revision surgery must address this loss of bone and may be achieved through either bone grafting or use of appropriate revision prosthesis components.

Computer-based assessment and classification of periacetabular osteolytic lesions: A new method.

Although it is currently the gold standard for the treatment of primary and secondary coxarthrosis, total hip arthroplasty is associated with long-time complications, primarily, polyethylene liner wear, and production of debris that lead to peri-prosthetic osteolysis and resultant aseptic mobilization. (The definition of these osteolytic areas is based on a radiographic classification first described by DeLee and Charnley in 1976.) We introduce a new radiographic classification method, based on the well-known measuring software Roman v.170 (Cook e Poullain [2002-2005, Institute of Orthopaedics, Oswestry, U.K.]) that is designed to quantify radiologic parameters. Two case studies are also described. This original method can be easily employed, and returns a precise angular classification of the position of the osteolytic area and a computerized calculation of the extent of the osteolytic lesion.

Review article: bone defect classifications in revision total knee arthroplasty.

There are several classification systems for bone defects in revision total knee arthroplasty. Each has its own drawbacks, and none satisfies all the clinical demands. Therefore, a new classification system and treatment guideline based on a combination of criteria (location, side, containment, and severity of the bone defect) is necessary.

The validity of using administrative claims data in total joint arthroplasty outcomes research.

The purpose of this study was to evaluate concordance between administrative and clinical diagnosis and procedure codes for revision total joint arthroplasty (TJA). Concordance between administrative and clinical records was determined for 764 consecutive revision TJA procedures from 4 hospitals. For revision total hip arthroplasty, concordance between clinical diagnoses and administrative claims was very good for dislocation, mechanical loosening, and periprosthetic joint infection (all kappa > 0.6), but considerably lower for prosthetic implant failure/breakage and other mechanical complication (both kappa < 0.25). Similarly, for revision total knee arthroplasty diagnoses, concordance was very good for periprosthetic fracture, periprosthetic joint infection, mechanical loosening, and osteolysis (all kappa > 0.60), but much lower for implant failure/breakage and other mechanical complication (both kappa < 0.24). Concordance for TJA-specific procedure codes was very good only for revision total knee arthroplasty patellar component revisions and tibial insert exchange procedures. Total (all-component) revisions were overcoded for hips (00.70) and undercoded for knees (00.80). Improved clinical documentation and continued education are needed to enhance the value of these codes.

[Benign odontogenic ectomesenchymal tumors]. / Benigne odontogene ektomesenchymale Tumoren.

The group of odontogenic ectomesenchymal tumors consists of odontogenic fibroma (epithelium-rich and epithelium-poor types), odontogenic myxoma, and cementoblastoma. Whereas odontogenic fibromas and cementoblastomas are very rare lesions, odontogenic myxoma is the fourth common odontogenic tumor, preceded only by keratocystic odontogenic tumor, the odontomas, and ameloblastoma. The diagnosis of cementoblastoma rests on its connection to the root of a tooth. The differentiation of odontogenic fibroma and myxoma from other lesions, especially from normal structures such as dental follicles and papillae, may be challenging if the X-ray appearance (localized osteolysis containing a tooth) is not appreciated and subtle histological clues (remainders of inner enamel epithelium at the surface of the lesion, dentin fragments) are not properly recognized. While odontogenic fibromas have almost no tendency for recurrence and are treated by enucleation or local excision, cementoblastomas and especially odontogenic myxomas have a high percentage of recurrence if intralesional procedures are applied. Hence, complete resection with free margins is recommended--at least for larger odontogenic myxomas and, especially, lesions in the maxilla--to prevent further extension to the orbita or base of the skull.

Paget's disease of bone and genetic disorders of RANKL/OPG/RANK/NF-kappaB signaling.

Identification of the RANKL/OPG/RANK/NF-kB (receptor activator of nuclear factor kappa-B ligand / osteoprotegerin) signaling pathway as the major regulatory system for osteoclastogenesis began with discovery of these ligands and receptors in the tumor necrosis factor (TNF) superfamily. Subsequently, genetically altered mice revealed physiologic roles for these proteins in bone biology. However, full appreciation of their significance for the human skeleton came from clinical characterization of several extremely rare, heritable disorders followed by discovery of their genetic bases. Familial expansile osteolysis (FEO) is an autosomal dominant disorder featuring constitutive activation of RANK due to an 18-bp tandem duplication in its gene (TNFRSF11A). A similar, 27-bp duplication causes what has been called a familial form of early-onset Paget's disease of bone (PDB2). Expansile skeletal hyperphosphatasia (ESH) is allelic to FEO and PDB2 and involves a 15-bp tandem duplication in TNFRSF11A. Autosomal recessive inheritance of deactivating mutations of the gene encoding OPG (TNFRSF11B) causes most cases of juvenile Paget disease. These disorders feature high bone turnover, deafness during early childhood, "idiopathic external lysis" of adult teeth, and sometimes focal lesions in appendicular bones that mimic active PDB. Biochemical markers indicate rapid skeletal remodeling. In FEO, osteolysis progresses to fat-filled bone rather than to osteosclerosis. Antiresorptive therapy with bisphosphonates can be effective for each disorder.

The femur in revision total hip arthroplasty evaluation and classification.

Femoral revision total hip arthroplasty is a technically demanding procedure. In addition to these technical issues, preoperative planning can be challenging and with multiple reconstructive options available, the decision-making process can be complex. The ability to preoperatively determine the most appropriate option for reconstruction greatly assists with ensuring that the appropriate implants and instruments are available at the time of surgery. A classification of femoral bone loss is presented that guides the surgeon in selecting an appropriate method of reconstruction.

Use of structural allografts in acetabular revision surgery.

Bone loss is a challenging problem with complex acetabular revisions. With an adequate biologic and mechanical environment, uncemented hemispheric component reconstructions have provided long-term durable results for acetabular revisions. Decisions about reconstructive options can be made with the aid of a classification system that addresses the location and severity of bone loss as it relates to achieving the prerequisites for biologic fixation with a hemispheric component. Structural allograft may be used to provide a mechanical environment that supports host bone ingrowth into an acetabular component. Alternatively, structural allograft may allow restoration of joint mechanics in situations where host bone loss precluded biologic fixation. We describe the indications and technique for the use of structural allograft in revision acetabular surgery.

[Analysis of validity and reliability of three radiographic classification systems for preoperative assessment of bone stock loss in revision total hip arthroplasty]. / Gültigkeit und Reproduzierbarkeit radiologischer Klassifikationskriterien des knöchernen Substanzdefekts vor Revisionshüftendoprothetik.

AIM: It was the purpose of this prospective study to analyze validity and reliability of three different radiographic classification systems, which are used to assess bone stock loss prior to revision total hip arthroplasty. METHOD: Investigation was performed using the classification systems according to 1) Paprosky et al., 2) Hungerford et al., and 3) the German Society of Orthopaedics and Traumatology (DGOT). Twenty-eight consecutive patients with diagnosis of aseptic failure of total hip arthroplasty were enrolled in the study. Interrater agreement was analyzed by evaluating the classifications preoperatively by three investigators with different level of clinical experience using a blinded observer technique. Validity was analyzed by comparison of preoperative radiographic findings (n = 3) and an intraoperative control by visualization and palpation (n = 1). Spearman coefficient of correlation (r(s)) was used to establish levels of agreement among multiple ordinal variables. RESULTS: Interrater reliability testing using paired comparison between the three investigators revealed non-homogeneous coefficients of correlation (r(s): Paprosky femur: 0.45 - 0.67, acetabulum: 0.38 - 0.63; Hungerford: 0.46 - 0.66; DGOT femur: 0.38 - 0.59, acetabulum: 0.42 - 0.76). Paired analysis of correlation between preoperative and intraoperative findings again showed non-homogeneous coefficients of correlation (r(s): Paprosky femur: 0.59 - 0.68, acetabulum: 0.39 - 0.70; Hungerford: 0.39 - 0.74; DGOT femur: 0.44 - 0.60, acetabulum: 0.36 - 0.76). In general, defects were grossly underestimated preoperatively. The level of experience did not influence the validity of measurements. CONCLUSION: Our results indicate that these classifications do not provide valid and reliable assessment of femoral and acetabular bone stock loss prior to revision total hip arthroplasty.

Bone scintiscanning in osteolytic lesions.

Osteolytic lesions seen on plain radiographs can be caused by various disorders of the bones such as simple bone cyst, aneurysmal bone cyst, plasmacytoma, giant cell tumor, eosinophilic granuloma and tuberculosis. We studied prospectively Tc-99m-methylene diphosphonate bone scan findings in osteolytic lesions seen radiologically and followed them to histopathology. Interestingly, the scans in these patients helped to show if the lesions were monoostotic or polyostotic and, in some cases, ruled out malignant or infective etiology.

A comparison of the reliability and validity of bone stock loss classification systems used for revision hip surgery.

Three femoral (Paprosky, American Academy of Orthopaedic Surgeons [AAOS], and Endo-Klinik) and 2 acetabular (Paprosky, AAOS) bone stock loss classification systems were evaluated for reliability. Four observers (2 consultants, 2 registrars) graded the bone loss in 25 patients using preoperative radiographs. Grading was repeated after a minimum of 2 weeks. Interobserver and intraobserver reliability was investigated. The kappa statistic was used to assess levels of agreement. Intraobserver agreement ranged from poor to good. Interobserver agreement ranged from fair to moderate. The validity of the Paprosky classification system was evaluated, comparing preoperative bone stock loss assessment with intraoperative findings. Agreement levels of moderate (femoral classification system) to good (acetabular classification system) were achieved. Bone stock loss classification systems are shown to be inconsistent and unreliable.

Assessment and classification of bone stock deficiency in revision total hip arthroplasty.

It is critical for appropriate treatment choices in revision total hip arthroplasty that bone stock deficiency be assessed and classified. Acetabular and femoral defects must be separately assessed, although a combined assessment is needed at the time of surgery to select the appropriate match of components for a given patient. Classification systems help surgeons predict defects and determine reconstruction planning prior to surgery. This article presents the senior author's classification of acetabular and femoral defects for revision total hip arthroplasty.

Femoral bone loss in total hip arthroplasty: classification and preoperative planning.

A single comprehensive classification system that can adequately describe all types of bone loss associated with hip arthroplasty should become a standard for reporting purposes. There is a need for a critical appraisal of the classification systems currently in use and, through a consensus, for development of a system that will permit comparison between the reported results of different techniques. Although no one classification system is ideal, the one proposed by the AAOS Committee on the Hip is the most comprehensive and the most consistently used. It addresses not only revision total hip arthroplasty but also primary hip replacement. It also addresses other conditions related to problems with the bone stock, such as those resulting from a previous hip arthrodesis on the acetabular side and femoral stenosis and malalignment on the femoral side. The only drawback to this classification system is its complexity; however, the problem of acetabular and femoral bone loss is of sufficient complexity and variety that a simple classification system, although ideal, cannot be comprehensive. Regardless of the absence of a common language and a comprehensive classification system that is applicable to all types of reconstructions, it is clear that femoral bone loss is a problem that will continue to challenge orthopaedic surgeons. It is only by careful and methodical analysis of patients who have femoral bone loss and by meticulous attention being paid to detail in preoperative evaluation and investigation, surgical planning, and the recording of outcomes that we will be able to improve our treatment of this difficult problem.