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Bone quality, initial fracture displacement, severity of fracture comminution, accuracy of fracture reduction, and the placement of the internal fixation device are important factors that affect fixation stability. New high strength cements that are susceptible to remodeling and replacement for fracture fixation may lead to improved clinical outcome in the treatment of hip fractures. Norian SRS is an injectable, fast setting cement that cures in vivo to form an osteoconductive carbonated apatite of high compressive strength (55 MPa) with chemical and physical characteristics similar to the mineral phase of bone. It can be used as a space filling internal fixation device to facilitate the geometric reconstruction, load transfer, and healing of bone with defects and/or fractures in regions of cancellous bone. Furthermore, this cement can improve the mechanical holding strength of conventional fixation devices. Use of this material potentially could improve fracture stability, retain anatomy during fracture healing and improve hip function, thus achieving better clinical outcomes. In vivo animal studies have shown the material's biocompatibility, and cadaveric studies have shown the biomechanical advantage of its use in hip fractures. Initial clinical experience (in 52 femoral neck fractures and 39 intertrochanteric fractures) showed the potential clinical use of this innovative cement in the treatment of hip fractures.

Small particles of biomaterials used in orthopaedic surgery have been shown to induce the resorption of bone. The purpose of this study was to determine whether phagocytosable particles of hydroxyapatite had an adverse effect on bone ingrowth. Bone harvest chambers were implanted bilaterally in the proximal tibial metaphyses of 13 mature rabbits. The bone harvest chamber has a transverse 1-mm wide pore, providing a continuous canal through the chamber for tissue ingrowth. After an initial 6-week period for osseointegration of the bone harvest chambers, the contents of the canal were harvested at 3-or 6-week intervals. Hydroxyapatite particles (diameter, 5 mu) were mixed with a carrier solution, 1% sodium hyaluronate, and implanted in the canal of one chamber in each animal. The contralateral chamber was implanted with the carrier only and served as a control. Histological sections from the tissue harvested from the chambers were evaluated by light microscopy and histomorphometry, and the area of bone ingrowth was measured as a percentage of total area in each section. At 3 weeks there was more bone in the hydroxyapatite sections than in controls; at 6 weeks there was no difference. Hydroxyapatite particles were incorporated within the matrix of new ingrown bone at both time periods. There was no evidence of granuloma formation or inflammation. Previous studies have shown that particles of high density polyethylene and bone cement adversely affect bone ingrowth in this model. The present results suggest that hydroxyapatite particles, small enough to be phagocytosed by macrophages, did not have such effects.

Sixteen mature New Zealand female rabbits had cemented, tibial hemiarthroplasty of the right knee (correction of hip) using a stemmed, fluted, titanium-alloyed, condylar type prosthesis. In the fixated prosthetic group (eight rabbits), a 1.5-cm3 doughy bolus of polymethylmethacrylate (PMMA) was used to cement the prosthesis firmly. In the loose group (eight rabbits), the cement was allowed to cure ex vivo on the implant; the prosthesis was then implanted and rotated to ensure that it was loose fitting. Roentgenograms performed postoperatively and at three months were graded for new lucent lines. The implant area was harvested aseptically and cultured during a three-day period, and the cumulative collection of tissue culture supernatants was assayed for prostaglandin E2 (PGE2). The mean cumulative grading of new lucent lines was 0.4 +/- 0.2 (mean +/- SEM) for the fixated prosthetic group and 2.3 +/- 0.5 for the loose prosthetic group. Specimens from the nonloose group produced 8.85 +/- 1.44 ng of PGE2 on the right prosthetic side, and 17.29 +/- 3.72 ng of PGE2 on the left, nonimplanted side. Specimens from the loose prosthesis group produced 52.35 +/- 16.28 ng of PGE2 on the right prosthetic side and 17.29 +/- 3.72 ng of PGE2 on the left, nonimplanted side. Increased PGE2 production relative to fixated prostheses was noted in the membranes surrounding loose prostheses. The left, nonimplanted sides were not statistically different. Roentgenographic and biochemical evidence indicates that a cemented tibial hemiarthroplasty implanted in the rabbit knee can provide a short-term model of arthroplasty loosening.

Fifteen mature, New Zealand, female rabbits were divided into two groups. Using sterile technique, a 6-mm drill hole was made in the tibia 1 cm distal to the knee joint bilaterally. The marrow was scooped out underneath the hole. The right tibia received Simplex particulate cement polymer and the left leg functioned as a prepared, but nonimplanted, control. All animals were fed a standard diet. Whereas the six animals in Group 1 received regular water, the nine animals in Group 2 drank water in which sodium naproxen was dissolved (1.375 mg per ml). The animals were killed after 16 weeks. The implant area was harvested under sterile conditions and maintained in tissue culture. The cumulative collection of tissue culture supernatants over a three-day period was assayed for Prostaglandin E2 (PGE2) via radioimmunoassay. Specimens from Group 1 produced an average of 106.0 +/- 10.9 ng PGE2 on the right side, and 35.3 +/- 6.0 ng PGE2 on the left side. Specimens from Group 2 produced an average of 31.1 +/- 6.1 ng PGE2 on the right experimental side and 26.0 +/- 5.1 ng PGE2 on the left control side. The ratio of PGE2 values for the right divided by the left side yielded higher values in Group 1, compared to Group 2. Cement polymer particles have been shown to produce a florid foreign body histologic reaction similar to that associated with prosthetic loosening in man. This experiment has demonstrated that the increased PGE2 production by the membrane surrounding particulate cement polymer can be suppressed by the administration of an oral cyclo-oxygenase inhibitor. PGE2 has been previously shown to induce bone resorption in vivo and in vitro. The use of nonsteroidal antiinflammatory drugs may be indicated in retarding the bone loss associated with early prosthetic loosening.

Fourteen mature New Zealand white female rabbits were allocated into two groups. Group 1 received a bolus doughy Simplex polymethylmethacrylate (PMMA) cement injected into the proximal tibia through a drill hole. Group 2 received an equal volume of particulate PMMA cement powder. The operated but nonimplanted left tibiae served as controls. The animals were killed after four months. The membrane surrounding the implant area was harvested aseptically and grown in tissue culture. The supernatants were assayed for prostaglandin E2 (PGE2) via radioimmunoassay. Bulk cement specimens produced on average 12.39 +/- 4.11 ng PGE2 on the right experimental side and 12.29 +/- 3.56 ng PGE2 on the left control side (not statistically different). Cement powder specimens produced 8.82 +/- 1.64 ng PGE2 on the right experimental side, which was statistically different from 4.21 +/- 0.88 ng PGE2 produced on the left control side. The ratio of PGE2 values for the right divided by the left side and the arithmetic difference between right and left sides were significantly higher in the particle group compared with the bulk group. Small, undigestable cement particles may be phagocytosed by foreign-body giant cells and histiocytes and then extruded into the extracellular compartment, along with substances such as PGE2. PGE2 has been implicated as the biologic mechanism for stimulating the bone lysis associated with prosthetic loosening.

All primary condylar total knee replacement arthroplasties (TKAs) performed from 1977 to 1984 at the authors' institution were divided into two groups based on the use of continuous passive motion (CPM) in the immediate postoperative period. The control group consisted of 73 patients who were treated with 95 TKAs without postoperative CPM. The average age was 65.4 years. The study group consisted of 38 patients who had 51 TKAs in which CPM was used postoperatively. The mean patient age was 62.8 years. The most common diagnoses in both groups were osteoarthritis and rheumatoid arthritis. Range of motion (ROM) was recorded preoperatively, at discharge, at three months, one year, two years, and at the last follow-up visit. There were no statistically significant differences in the ROM between the two groups at any of these time periods. At two years, the mean flexion and extension in the study group were 99 degrees and -4 degrees, respectively, compared to 103 degrees and -5 degrees in the control group. The average hospital stay was 11.2 days in the study group, whereas it was 15.1 days in control group. In the control group, there was one superficial infection, no deep infections, and four pulmonary emboli compared with three superficial infections, two deep infections, and no pulmonary emboli in the study group. There was no difference in the transfusion requirements between the two groups. CPM is advocated by the authors to help achieve discharge ROM earlier, but the protocol has been changed to begin CPM on the second postoperative day to allow the wound to stabilize.

Thirty-two cemented revision hip arthroplasties done with a straight-stem Muller prosthesis were reviewed an average of 3 years after operation (range, 2-4.4 years). Acetabular revision, performed in 29 cases, we done with a support ring, mesh, or bone graft in 18 of 29 (62%) cases. Acetabular and femoral cement pressurization techniques were not used. Trochanteric osteotomy was done in 15 cases (47%). The average patient age was 60.2 years (range, 20-85 years). Based on the clinical rating system of Swanson and Evarts, there were 21 (65.6%) excellent, 2 (6.3%) good, 8 (25%) fair, and 1 (3.1%) poor results. The clinical outcome was better after revision from a resurfacing arthroplasty (87.5% good/excellent results) than from uni/bipolar or total hip arthroplasty (60%). Radiographic examination suggests that two femoral components and one acetabular component are loose. These patients have a fair clinical rating. None have been revised. Trochanteric wire breakage (60%) and displacement (26.7%) was common if trochanteric osteotomy was done.

Twelve surface replacement arthroplasties were performed on the hips of ten mongrel dogs using scaled-down replicas of the Wagner prosthesis. The contralateral hips and two further animals served as nonoperated controls. Animals were killed 5 months postoperatively. Clinical, radiological, histological and fluorochrome-labelling studies were employed to assess the bony and soft tissue reaction to resurfacing arthroplasty. There was no clinical or radiographic evidence of prosthetic loosening. Histological examination disclosed a thick foreign body and chronic inflammatory membrane containing acrylic cement and polyethylene wear particles at the bone-cement interface of both components. Generally, the bone marrow and trabecula were viable. There was evidence of increased bony remodelling and new bone formation in the subchondral area. The similarity between the above findings and those of aseptic component loosening in man suggests a mechanism whereby wear debris initiate a biological foreign body reaction culminating in component loosening.

Using clinical, radiographic, and pathological data, we investigated eighteen cases of early aseptic failure of an implant in patients who had undergone reconstruction of the hip with a Wagner resurfacing prosthesis. Sixteen patients required revision for loosening of the acetabular component, with eight of them also demonstrating loosening of the femoral component. One patient had loosening of the femoral component without failure of the acetabular component, and one patient sustained a femoral neck fracture that was associated with osteonecrosis. Six of the patients with loosening of the acetabular component had an associated significant loss of acetabular bone stock. Loosening was associated with the development of a membrane at the bone-cement interface in all patients. Histological examination of the membrane demonstrated a marked foreign-body response to wear products from the arthroplasty. Bone resorption appeared active at the bone-membrane interface. We concluded that the acetabular component of the Wagner prosthesis is prone to early loosening and that the early loosening is potentiated by a foreign-body response to debris resulting from arthroplastic wear.

Summary Background and objectives Rheumatoid arthritis (RA) is a chronic inflammatory disease of unknown etiology. It is known that RA patients have a reduced life expectancy when compared with the general population. Rheumatic diseases are numerous and occur with high variability; some of them develop very rapidly while others occur chronically provoking disability throughout life. Anesthetic risks in osteoarticular disorders involve not only the mechanical deformations caused by the disease, but also the cardiovascular, respiratory, renal, and digestive systems. Contents The purpose of this review was to stress the importance of stages in disease process that may affect anesthesia control before, during, and after surgery, highlighting the authors’ experience in a retrospective review of patients with juvenile rheumatoid arthritis (JRA) undergoing placement of orthopedic prosthesis with emphasis on intubation techniques. Conclusions Rheumatoid arthritis patients can present a number of complex problems for the anesthesiologist. This requires careful preoperative evaluation; anesthesia requires experience with the technique; and postoperative care should be judiciously chosen to meet the specific needs of the patient. The procedure requires effective communication among surgeon, rheumatologist and anesthesiologist so each member of the multidisciplinary team can contribute with his/her expertise in order to better benefit the patient.

We reviewed early and late motion changes of the hip in 102 hemophiliacs with a mean follow-up of 7 years. Sixty patients (59%) had at least one hip bleed. Sixty-four hips in 49 patients demonstrated at least a 15 degree change in range of motion (ROM) at some time. At final review, only 34 of these 64 hips (53%) lost motion. Patients whose hips lost motion were just as likely to report hip bleeds as those who lost no motion. Twenty hips examined within 2 months of bleeding lost significant motion, but most motion returned within a year. The relationship between hip girdle bleeding and ROM remains obscure.

The radiographs of 97 patients (117 hips) who had a straight-stem Muller femoral component and a non-metal-backed acetabular component were reviewed to determine whether the mode of acetabular loosening predicted by finite element stress analysis (FESA) is observed clinically. The follow-up period averaged 3.1 years (range, 2.0-4.6 years). Significantly more lucent lines were present in zones 1 and 3, compared with zone 2 (P less than .01). This finding corroborates the predictions of FESA and suggests that the production of acetabular lucent lines is due in part to chronic mechanical overload.

Three femoral components (one cemented and one uncemented straight-stem Muller and one uncemented Anatomic Medullary Locking) were placed into cadaveric or commercially available plastic femora to establish that rotation of the femur can simulate changes in femoral component alignment on the anteroposterior radiograph. The change in alignment is governed by the position of the prosthesis within the femoral canal. If the stem of the prosthesis is positioned posteriorly in the canal, external rotation simulates valgus; internal rotation results in a varus orientation. If the prosthetic stem is located anteriorly in the canal, the reverse is true. This effect was noted in all specimens for values as small as 20 degrees of rotation. Because a change in the position of a prosthesis may signify loosening, it is recommended that standardized positioning techniques be used for radiographic analysis of total hip arthroplasties.

Modern surgical antisepsis is now more than 120 years old. After Louis Pasteur’s discovery that bacteria caused fermentation, Joseph Lister recognized that bacteria also caused putrifaction in wounds. He utilized this information in 1865, in the treatment of a patient with an open tibial fracture, to which he applied lint dipped in liquid carbolic acid (38). His concept of chemical sterilization of the wound before bacteria could multiply sufficiently provided the groundwork for our modern era of surgical antisepsis.

Fourteen mature New Zealand white female rabbits underwent implantation of a bulk pellet and of particulate (less than 1,000 micron) ultra-high-molecular-weight polyethylene (UHMWPE), through a drill hole in the proximal right tibia. The left tibia served as a drilled but nonimplanted control. The rabbits were killed after 16 weeks. Histologic examination of the bone-implant interface in the bulk UHMWPE group disclosed a fibrous tissue membrane with infrequent giant cell and histiocytic clusters at surface irregularities. The particulate group demonstrated positively birefringent UHMWPE fragments, rimmed by foreign body giant cells and histiocytes, embedded in a loose connective tissue. The histologic response to particulate UHMWPE is similar to that seen surrounding loose total joint arthroplasties in humans.

Complex interactions among cells of the monocyte-macrophage-osteoclast lineage and the mesenchymal stem cell-osteoblast lineage play a major role in the pathophysiology of bone healing. Whereas the former lineage directs inflammatory events and bone resorption, the latter represents a source of cells for bone regeneration and immune modulation. Both of these lineages are affected by increasing age, which is associated with higher baseline levels of inflammatory mediators, and a significant reduction in osteogenic capabilities. Given the above, fracture healing, osteoporosis, and other related events in the elderly present numerous challenges, which potentially could be aided by new therapeutic approaches to modulate both inflammation and bone regeneration.

We summarize research approaches and findings on bone healing and regeneration that were presented at a workshop at the 60th annual meeting of the Orthopedic Research Society (ORS) in New Orleans in 2014. The workshop was designed to discuss the role of inflammation in bone regeneration in the context of fundamental biology, and to develop therapeutic strategies that involve immune modulation. Delayed or non-healing of bone is a major clinical problem, with around 10% of fracture patients suffering from unsatisfying healing outcomes. Inflammation is traditionally seen as a defense mechanism, but was recently found essential in supporting and modulating regenerative cascades. In bone healing, macrophages and T- and B-cells interact with progenitor cells, bone forming osteoblasts and remodeling osteoclasts. Among the cells of the innate immunity, macrophages are promising candidates for targets in immune-modulatory interventions that would overcome complications in bone healing and bone-related diseases. Among the cells of the adaptive immune system, CD8+ T cells have been shown to have a negative impact on bone fracture healing outcome, whereas regulatory T cells could be promising candidates that have a positive, modulating effect on bone fracture healing. This workshop addressed recent advances and key challenges in this exciting interdisciplinary research field.

Twenty-one mature New Zealand white female rabbits were allocated into three groups of seven rabbits. Group I received a bolus of doughy Simplex polymethylmethacrylate (PMMA) cement injected into the proximal tibia through a drill hole. Group II received a preformed, cooled, bulk PMMA pellet. Group III had particulate PMMA powder implanted. The operated, but nonimplanted, left tibiae served as controls. Animals were killed after four months. Histologically, both Group I and Group II demonstrated a thin, fibrous tissue membrane at the implant interface. Particulate PMMA (Group III) stimulated a much thicker, florid, foreign body reaction composed of histiocytes and giant cells. The foreign body response to particulate acrylic cement was similar to that seen in failed cemented joint replacement arthroplasty in humans.

The clinical and roentgenologic data from 31 excised components from 19 revision arthroplasty cases were correlated with the histology and biochemistry of the membrane at the bone-cement or bone-prosthesis interface. Twenty-seven components were cemented and four were uncemented. Twenty-four implants were clinically and roentgenologically loose, one was possibly loose, and six were well fixed. Loose components, whether cemented or not, demonstrated statistically higher prostaglandin E2 levels in the surrounding membrane compared to the nonloose group. Collagenase and M-collagenase levels were absent or insignificantly low in all specimens; no detectable interleukin 1 beta was found. This suggests that prostaglandin E2 may be associated with the bone lysis associated with prosthesis loosening.

Five pelvises were photographed, roentgenographed, and sequentially sectioned or reamed to determine the location and appearance of the acetabular teardrop figure. The teardrop is located inferomedially in the acetabulum, just superior to the obturator foramen. The lateral lip is the exterior, and the medial lip is the interior of the acetabular wall. The ilioischial line projects over the medial acetabulum only fortuitously on the straight anteroposterior (AP) roentgenogram. Because of parallax, the relationship between the ilioischial line and the teardrop changes for views varying as little as 10 degrees in horizontal obliquity from the true AP roentgenogram. Because the teardrop comprises a well-defined, constant portion of the medial acetabular wall whereas the ilioischial line does not, the authors recommend using the acetabular teardrop rather than the ilioischial line for the detection and measurement of medial and superior acetabular migration.

Experiments on rabbits were performed to determine whether continuous irrigation of a synovial joint produced irreversible degenerative changes in the articular cartilage. Continuous irrigation of a synovial joint permits observations of the effect on articular cartilage of altering the intra-articular environment. The right knee joints were irrigated with normal saline for varying periods, up to 14 days, and the left knees served as nonirrigated controls. One group of animals (short-term) was killed immediately following irrigation, while another group (long-term) was assessed after six months of cage activity following the irrigation period. Within each group, half were skeletally immature and half were mature. No differences in cell density, nuclei-to-lacunae ratio, or the ratio of calcified layer to total cartilage thickness were found in any group. Irrigation did produce a significant reduction in matrix staining with safranin-O. This was first detectable following three days of irrigation and was severe by seven to 14 days. Staining properties returned to normal after six months of cage activity. No obvious difference was found between immature and mature animals.