Quantitative comparison of the histological effects of particulate polymethylmethacrylate versus polyethylene in the rabbit tibia

Fourteen mature female New Zealand White rabbits underwent implantation of Simplex polymethylmethacrylate (PMMA) powder or particulate (average 67 microns) ultrahigh-molecular-weight polyethylene (UHMWPE) through a drill hole in the proximal right tibia. The left tibia functioned as a prepared but nonimplanted control. Animals were killed after 16 weeks. Histological examination of the bone-implant interface in the particulate PMMA group disclosed a florid foreign-body reaction with the presence of giant cells and histiocytes. The particulate UHMWPE group demonstrated positively birefringent UHMWPE fragments, rimmed by foreign-body giant cells and histiocytes, embedded in a loose connective tissue stroma. UHMWPE interfaces were thicker and contained more histiocytes and fibrocytes; PMMA interfaces contained more marrow cells and lymphocytes. This study underscores the importance of biomaterial debris in the process of aseptic loosening of cemented joint arthroplasties.

[Gentamycin concentration in the milk of a mother after treatment by implantation of a Septopal chain]

The author implanted 90 beads of Septopal into the osteomyelitic femur of a wet mother. The excretion of gentamycin in the mother's milk was continuously examined. The investigations revealed that the excretion of gentamycin with the mother's milk was so minimal that it did not signify any risk for the newborn baby.

Prostaglandin E2 levels in the membrane surrounding bulk and particulate polymethylmethacrylate in the rabbit tibia. A preliminary study

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.

Development and application of antibiotic-loaded bone cement beads

The authors presented an overview of the development of antibiotic-loaded bone cement beads and their indications for usage, method of application, advantages, disadvantages, and causes of failure. This method of treatment for bone and soft tissue infections of the foot is not a panacea and should be used only in selected cases. The vascular status and the physiologic ability of the patient to heal a peripheral wound or infection are the basis for the success of this method of therapy. European literature makes little mention of adjunctive systemic antibiotic therapy with local antibiotic-loaded bone cement bead use. It is the authors' opinion that clinical judgment should be used to determine the necessity for such therapy.

[Reactions of the osseous site following implantation of cemented endoprostheses in the femur]

17 autopsy femora with fixed cemented endoprostheses were sectioned horizontally and studied histologically, morphometrically and microradiographically. The implantation period varied between 0 and 12 years. It was frequently found that in distal segments the implant was already loosened shortly after implantation. The morphometrical analyses showed no significant bone changes distal to the trochanter minor. Enhanced microresorption and areas of reduced mineralization were found at the cement-bone interface. The total bone alterations, however, are not very extensive and seem not to be responsible for aseptic loosening, but the frequently inferior fixation instead.

Injection-corrosion-lavage. Techniques for study and description of vascular anatomy in the hand

The venous anatomy of the human hand has not been accurately described. Two main reasons for this deficiency in our knowledge are apparent: technical difficulties involved with dissection and imaging of the vessels, and the seemingly limitless number of topographic patterns in this field. This paper introduces firstly, a method for injection and corrosion of hand specimens, and secondly, a routine for describing the venous anatomy, primarily based on their function, and only secondarily on their position or topography.

[Giant cell tumor of bone. An analysis of 69 cases]

1. The tumor stage of the giant cell tumor is an indicator for the prognosis and the need for adjuvant therapy. 2. Intralesional excisions without an adjuvant result in high rates of recurrence. 3. Polymethyl methyl acrylate (PMMA) largely prevents recurrences, provides stability and makes early functional treatment possible. 4. Broad excisions should only be performed in bone which is dispensable. 5. Recurrences frequently manifest themselves by pain. They can be removed intralesionally, as in primary therapy.

[Revision interventions in aseptic and infected loose knee endoprostheses]

From 1984 to 1988 20 revisions for aseptic or septic loosening of knee prosthesis were performed. In 12 case there was an aseptic- and in 8 cases a septic loosening of the prosthesis. Most revision surgery for loosening of knee replacement needs reconstruction of bone stock. In loosening of unconstrained knee prostheses (uni-, totalcondylar knees) it was possible to insert a total condylar knee for revision surgery. Partially gross deviations had to be corrected, but in all cases a good alignment and ligamentous stability were effected. In septic loosening we had good experience with the two stage procedure. We temporarily implanted a gentamycine-PMMA-Spacer to avoid soft tissue contracture and to inhibit fusion of the cancellous bone. Arthodesis after knee replacement is difficult to manage, because the sclerotic bone of the site the prosthesis doesn't easily fuse.

[Improving fiber adhesion by surface oxidation in carbon fiber reinforced bone cement]

The mechanical superiority of carbon fiber reinforced PMMA containing additional apatite was shown previously. For further improvement these carbon fibers were now submitted to a superficial oxidation treatment by HNO3. A closer contact between the carbon fibers and PMMA and even trabeculae-like adhesions were detected by Scanning Electron Microscopy. The fatigue strength of the carbon fiber reinforced bone cement could be increased at 17% by this oxidation treatment. This increase, however, is less than that observed in the case of other fiber reinforced composites. Most likely this is caused by the pronounced polymerisation contraction of PMMA. Further improvement of the adhesion of the fibers to cement may be achieved by different oxidation techniques, further extraction of foreign substances or graft polymerization of the carbon fibers by PMMA or other polymers.

Air embolism during total hip replacement: comparison of two surgical techniques

The frequency of air embolism was studied in 21 patients during total hip replacement. Two groups were examined, one having femoral shaft cement insertion by hand, the other by Exeter cement gun. Venous air embolism was common throughout the hip surgery, but was especially so during prosthesis positioning in the femoral shaft. There were fewer air emboli and cardiovascular sequelae detected in the gun-inserted cement group, and the only patients to show clinically significant cardiovascular abnormalities during insertion of cement and prosthesis were those having cement insertion by hand. We conclude that the incidence of air embolism and associated cardiovascular changes during total hip replacement may be expected to be reduced in those patients in whom a cement gun is used to place the cement.

[Giant cell tumor of bone]

This retrospective study analyses 67 patients with 69 giant cell tumors of bone staged according to the Surgical Staging System of benign and malignant lesions of Enneking (1980, 1986). A significant correlation between Stage 2 and Stage 3 benign lesions in respect to local recurrence as well as between the therapeutic procedures and recurrence was found. Intralesional excision with temporary acrylic cement implantation showed to be the preferable initial treatment of these tumors. Special attention to surgical staging, surgical techniques and a supervised rehabilitation program minimize the incidence of recurrence and at the same time giving am maximum of joint function.

Wound and serum levels of tobramycin with the prophylactic use of tobramycin-impregnated polymethylmethacrylate beads in compound fractures

Antibiotic-impregnated polymethylmethacrylate (PMMA) beads have been useful in treating orthopedic infections. Local delivery has been reported to establish wound antibiotic levels well above the therapeutic range while avoiding serum levels associated with increased incidence of side effects. After operative debridement, 70 patients with compound fractures were treated prophylactically with tobramycin-impregnated PMMA beads. Observations of antibiotic levels in 27 patients demonstrated antibiotic levels in the wound drainage and clot that were significantly in excess of the usual therapeutic range for tobramycin and simultaneous nontoxic serum levels. Significant levels of tobramycin can be achieved in the extracellular fluid at the fracture site when tobramycin-impregnated PMMA beads are placed in the wound after irrigation and debridement.

Two-year inhalation carcinogenesis studies of methyl methacrylate in rats and mice: inflammation and degeneration of nasal epithelium

Methyl methacrylate (MMA), a liquid monomer, is used as a chemical intermediate in the manufacture of plexiglass and other acrylic products and as "bone cement" in orthopedic and dental surgery. Toxicology and carcinogenesis inhalation studies of MMA were conducted because of: (1) widespread human exposure; (2) evidence of mutagenicity; and (3) inadequacy of previously conducted long-term oral, dermal, and inhalation studies. Groups of 50 male F344/N rats were exposed to MMA by inhalation at 0, 500, or 1000 ppm, female F344/N rats at 0, 250, or 500 ppm, and male and female B6C3F1 mice at 0, 500, or 1000 ppm, 6 h a day, 5 days a week for 102 weeks. Survival rates of male and female rats and mice exposed to MMA were similar to those of their respective controls. Body weights were reduced in the low and high dose male (3-6% and 5-10%, respectively) and female (5-7% and 8-10%) rats exposed to MMA for more than 80 weeks and in male (7-19% and 6-17%) and female (0-13% and 0-17%) mice for more than 20 weeks. Inhalation exposure of MMA for 102 weeks did not induce any increased incidences of neoplasms in male or female rats or mice. Non-neoplastic lesions in the nasal cavity of MMA-exposed rats and mice were significantly increased and these included inflammation and degeneration of the olfactory epithelium of MMA-exposed male and female rats and inflammation, hyperplasia, cytoplasmic inclusions in the respiratory epithelium, and degeneration of the olfactory epithelium in male and female mice.

The effects of bulk versus particulate polymethylmethacrylate on bone

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.

Role of gentamicin-impregnated cement in total joint arthroplasty

Palacos-Gentamicin (PG) was used in 130 joint arthroplasties at The Hospital for Special Surgery. At an average follow-up of 2.5 years (range, 2 to 5), the overall recurrence rate of infection was 3.8 per cent. Only one (2.0 per cent) infection occurred where the bacteria were sensitive to PG and there were no infections in the two-stage reimplantation group. There have been no adverse effects from the gentamicin and the inferior intrusion properties of the PG have not been reflected in the clinical or radiographic results.

[Occlusion therapy in chronic recurrent parotitis? A report of clinical experiences with the use of a fibrin glue-gentamycin mixture]

Treatment of chronic recurrent parotitis was attempted in 12 patients by occlusion of Stensen's duct with a mixture of fibrin glue and gentamycin. This therapy failed to induce long-term improvement. It is recommended to undertake surgical intervention as soon as possible in all cases of progressive chronic recurrent parotitis.

Results of acetabular revisions with newer cement techniques

It is the purpose of this article to evaluate the authors' results of cemented acetabular reconstructions in revision surgery for massive osseous deficiencies with the previously stated techniques. In addition, the authors will examine the results with respect to bone allografting and bone autografting and their compatibility with methyl methacrylate.

Centrifugation of antibiotic impregnated bone cement

Centrifugation is used to increase the strength of bone cement in total joint arthroplasty. Antibiotics have been incorporated into cement for the treatment and prophylaxis of infection. To determine the effect of centrifugation on antibiotic containing cement, tobramycin and cefamandole impregnated Surgical Simplex P polymethylmethacrylate was centrifuged using manufacturers' techniques. The concentration of antibiotics was measured throughout the cement column by a zone of inhibition bioassay. No difference in the distribution of the antibiotics could be demonstrated as compared to hand mixed controls. Centrifugation decreased the number of large air inclusions overall, however, a significant number were noted to remain at the top of the centrifugation gradient. It was concluded that centrifugation of an antibiotic impregnated bone cement, utilizing this technique, may be used without disturbing the antibiotic distribution. Discarding the top 1 cm of liquid centrifuged column to remove residual air inclusions is recommended.

A rat model of resorption of bone at the cement-bone interface in the presence of polyethylene wear particles

Resorption of bone and the formation of a membrane at the interface between acrylic cement and bone were induced by particles of high-density polyethylene that were similar in size to those that are present in the tissues surrounding a human joint prosthesis. A non-weight-bearing plug of methylmethacrylate was inserted through the knee joint into the distal part of the femur of the rat. The plug rapidly became surrounded by a shell of bone. After repeated injections of particles of high-density polyethylene into the knee joint, resorption of bone occurred at this stable interface. No resorption of bone occurred after the opposite knee was injected with a control preparation that did not contain particles. The resorption of bone that occurred around the plug after the injection of particles of polyethylene took place in the absence of mechanical causes for loosening and in the absence of infection.

Comparative evaluation of the diffusion of tobramycin and cefotaxime out of antibiotic-impregnated polymethylmethacrylate beads

Both tobramycin and cefotaxime diffuse from antibiotic-impregnated polymethylmethacrylate (PMMA) beads in quantities sufficient to inhibit the growth of bacteria on agar lawns or in broth cultures over a 28-day period. Extraction of antibiotic from tobramycin or cefotaxime-impregnated PMMA beads revealed that substantial amounts of both antibiotics remained within the beads despite 28 days of diffusion. Diffusion of antibiotic from the PMMA beads during the initial 3-5 days is much greater than occurs for the remainder of the 4-week period. The results of the study suggest that perhaps tobramycin of cefotaxime-impregnated PMMA beads would produce local levels of antibiotic high enough to sterilize a given dead space for a period of 28 days.

Problem prostheses: the radiologic evaluation of total joint replacement

The authors discuss and illustrate the various complications of total joint prostheses. Criteria for the evaluation of radiographs of total joint prostheses are presented.