Elucidating trends in revision reverse total shoulder arthroplasty procedures: a retrieval study evaluating clinical, radiographic, and functional outcomes data

BACKGROUND

The purpose of this study was to explore relationships between damage modes in explanted reverse total shoulder arthroplasty (RTSA) components, patient and radiographic risk factors, and functional data to elucidate trends in RTSA failure.

METHODS

Fifty RTSA systems, retrieved from 44 patients, with 50 polyethylene (PE) liners, 30 glenospheres, 21 glenoid baseplates, 13 modular humeral metaphases, and 17 humeral stems, were examined for damage modes, including abrasion, burnishing, dishing, embedding, scratching, and pitting. PE liners were also analyzed for delamination and edge deformation. Charts were reviewed for patient, surgical, and functional data. Pre-revision radiographs were analyzed for scapular notching and loosening.

RESULTS

Average term of implantation was 20 months (range, 0-81 months). Metallic components exhibited abrasion, burnishing, dishing, pitting, and scratching. PE liners displayed all damage modes. Damage was exhibited on 93% of glenospheres and 100% of PE liners. Of 29 aseptic shoulders, 13 showed evidence of scapular notching and 5 of humeral loosening. There was a moderate correlation between radiographically observed implant failure or dissociation and PE embedding (r = 0.496; P < .001). There were weak and moderate correlations between scapular notching severity and PE dishing (r = 0.496; P = .006), embedding (r = 0.468; P = .010), and delamination (r = 0.384; P = .040).

CONCLUSIONS

To date, this is the largest series of retrieved RTSA components and the first to relate damage modes to radiographic and clinical data. Most damage was observed on the PE liners, on both the articular surface and rim, and glenosphere components. Correlation of retrieval findings with radiographic and clinical data may help establish predictors of prostheses at risk for failure.

The Role of Computed Tomography in Evaluating Intra-Articular Distal Humerus Fractures

Computed tomography (CT) is often used to evaluate intra-articular distal humerus fracture patterns, but it increases radiation exposure and cost. We conducted a study to determine the effect of adding CT evaluation to plain radiographic evaluation on the classification of, and treatment plans for, intra-articular distal humerus fractures. Nine blinded orthopedic surgeons evaluated 30 consecutive fractures for classification and surgical approach. Evaluations were performed first using plain radiographs and then again using the same radiographs plus CT images. Statistical analysis was performed using the κ correlation coefficient and Cramer V testing. We hypothesized that adding CT images to plain radiographs would change the classification and treatment of these fractures and would improve interobserver agreement on classification and treatment. Intraobserver reliability (Cramer V) was fair (.393) for classification and moderate (.426) for treatment. Interobserver reliability (Cohen κ) did not improve with CT: For classification, κ was .21 without CT and .20 with CT; for treatment, κ was .28 without CT and .27 with CT. When classifying the fractures, attending surgeons chose the multiplanar fracture pattern 25.6% of the time without CT, and remained consistent at 23.3% with CT. Trainees chose this fracture pattern much less often without CT than with CT. Use of CT changed the treatment for multiplanar fractures (73.7% lateral approach vs 51.9% posterior approach with olecranon osteotomy). When added to plain radiographic evaluation, CT evaluation changes classification and treatment plans. Interobserver reliability did not improve. Less experienced surgeons were more likely to identify multiplanar fracture patterns with use of CT. We recommend performing CT for all intra-articular distal humerus fractures.

Surgical treatment of displaced proximal humerus fractures with a short intramedullary nail

BACKGROUND

The Polaris nail is an intramedullary device for treating displaced proximal humerus fractures with few published studies to support its use. Results of a consecutive series of patients treated with the Polaris nail are presented.

METHODS

Eighteen patients with a mean age of 71 years (range, 37-84) were treated for twelve 2- and six 3-part fractures. Radiographic results for all patients were evaluated. Thirteen patients with an average follow-up of 42 months (range, 24-84) were available for functional evaluation.

RESULTS

Seventeen of 18 patients healed. Postoperatively, the neck/shaft angle collapsed an average 11° (range, 5-30°) into varus. Nine of 18 patients had final neck/shaft angles <120° and were considered radiographic malunions. The mean Constant and American Shoulder and Elbow Surgeons (ASES) scores were 61 (range, 20-100) and 67 (range, 10-100), respectively. Forward elevation averaged 118°. Patients had an average 5/8 positive rotator cuff signs. Seven patients underwent reoperation for loss of fixation or prominent hardware, and 1 required revision to a hemiarthroplasty.

CONCLUSION

This study shows a higher than reported percentage of unsatisfactory results using the Polaris nail. The device violates the rotator cuff and is unable to resist the deforming forces that can lead to loss of fixation and varus collapse.

Review of fixation techniques for the four-part fractured proximal humerus in hemiarthroplasty

Introduction

The clinical outcome of hemiarthroplasty for proximal humeral fractures is not satisfactory. Secondary fragment dislocation may prevent bone integration; the primary stability by a fixation technique is therefore needed to accomplish tuberosity healing. Present technical comparison of surgical fixation techniques reveals the state-of-the-art approach and highlights promising techniques for enhanced stability.

Method

A classification of available fixation techniques for three- and four part fractures was done. The placement of sutures and cables was described on the basis of anatomical landmarks such as the rotator cuff tendon insertions, the bicipital groove and the surgical neck. Groups with similar properties were categorized.

Results

Materials used for fragment fixation include heavy braided sutures and/or metallic cables, which are passed through drilling holes in the bone fragments. The classification resulted in four distinct groups: A: both tuberosities and shaft are fixed together by one suture, B: single tuberosities are independently connected to the shaft and among each other, C: metallic cables are used in addition to the sutures and D: the fragments are connected by short stitches, close to the fragment borderlines.

Conclusions

A plurality of techniques for the reconstruction of a fractured proximal humerus is found. The categorisation into similar strategies provides a broad overview of present techniques and supports a further development of optimized techniques. Prospective studies are necessary to correlate the technique with the clinical outcome.

Cumulative exposure to tamoxifen: DNA adducts and liver cancer in the rat

Tamoxifen is a potent rat liver carcinogen, currently being used as a long-term chemopreventative for breast cancer in healthy women. The mechanism by which tamoxifen causes liver cancer in rats is known to be associated with the accumulation of tamoxifen DNA adducts in this organ. We have examined the dose-response relationship of tamoxifen-induced DNA adducts in the liver and the subsequent increase in the development of liver cancer, with and without phenobarbital promotion. Female Wistar (Han) rats were fed 420 ppm tamoxifen in the diet for 0, 1, 4, 8 or 12 weeks after which time rats were either examined immediately for hepatic tamoxifen-induced DNA damage using the 32P-Postlabelling assay, or left for lifetime for tumour assessment. A proportion of rats left for lifetime study were given phenobarbital in their drinking water. There was a clear dose-response relationship with respect to duration of tamoxifen exposure for both accumulation of DNA adducts and lifetime risk of liver cancer. In the absence of phenobarbital promotion there was a threshold value for tamoxifen-induced DNA adducts (180 adducts/10(8) nucleotides) and the subsequent induction of liver cancer. This study demonstrates the relationship between the accumulation of hepatic tamoxifen-induced DNA adducts and the development of liver cancer and establishes the threshold for hepatocarcinogenesis in terms of DNA adduct formation. These data could provide useful information in interpreting the relevance of low levels of DNA adducts in humans.

Tamoxifen induces endometrial and vaginal cancer in rats in the absence of endometrial hyperplasia

Tamoxifen was administered orally to neonatal rats on days 2-5 after birth and the subsequent effects on the uterus were characterized, morphometrically, over the following 12 months. Tamoxifen inhibited development of the uterus and glands in the endometrium, indicating a classical oestrogen antagonist action. Between 24 and 35 months after tamoxifen treatment there was a significant increase in the incidence (26%) of uterine adenocarcinomas and a 9% incidence of squamous cell carcinomas of the vagina/cervix in the absence of any oestrogen agonist effect in the uterus. This demonstrates that an oestrogen agonist effect is not an absolute requirement for the carcinogenic effect of tamoxifen in the reproductive tract of the rat. The unopposed oestrogen agonist effect of tamoxifen on the endometrium may not be the only factor involved in the development of endometrial cancers. It is possible that tamoxifen causes these tumours via a genotoxic mechanism similar to that seen in rat liver. However, using (32)P-post-labelling we failed to find evidence of tamoxifen-induced DNA adducts in the uterus. Tamoxifen may affect hormonal imprinting of oestrogen receptor responses in stem cells of the uterus, causing reproductive tract cancers to arise at a later time, in the same way as has been proposed for diethylstilbestrol. If these rodent data extrapolate to humans, then women who are taking tamoxifen as a chemopreventative may have an increased risk of vaginal/cervical cancer, as well as endometrial cancer.

Uterotrophic effects of tamoxifen, toremifene, and raloxifene do not predict endometrial cell proliferation in the ovariectomized CD1 mouse

The uterotrophic responses of ovariectomized CD1 mice to tamoxifen, toremifene, and raloxifene have been compared to 17beta-estradiol after a treatment period of 72 h. Uterine and vaginal weight, luminal epithelial thickening, and 5-bromodeoxyuridine (BrdU) labeling index in the endometrial stroma were examined. All three pharmaceuticals, as well as 17beta-estradiol, produced increases in the classic estrogen-dependent variables of uterine and vaginal weights after the 3-day treatment period. Tamoxifen, toremifene, raloxifene, and estradiol all increased luminal epithelial thickness, and increased the BrdU labeling index in the endometrial stroma of the uterus. Although the dose response for the uterotrophic effect and the vaginal weight increases for toremifene differed from tamoxifen and raloxifene, in that there was no dose at which these effects were maximal, the stimulation of BrdU labeling index in the endometrial stroma was dose dependent and very similar for all three, at the clinically relevant doses. Treatment-related hypertrophic effects were estimated by examination of the nuclear profile density in the endometrial stroma. Estradiol and tamoxifen caused a greater hypertrophic effect than toremifene and raloxifene, indicating that factors other than an increase in cell number contribute to the overall uterotrophic effect. This demonstrates that the use of uterine weight to estimate the relative estrogenicity of drugs could give a misleading impression of the response of the uterus to estrogen agonists. Variables, such as increased DNA replication, which may be more important to a subsequent potential carcinogenic process in the uterus, for a particular drug, requires separate evaluation.

Compartmentalized uterotrophic effects of tamoxifen, toremifene, and estradiol in the ovariectomized Wistar (Han) rat

The comparative uterotrophic responses of ovariectomized Wistar (Han) rats to tamoxifen, toremifene, and 17beta-estradiol have been determined over a period of 72 h. Uterine wet weight; luminal epithelial cell hypertrophy; and BrdU labeling index in the different tissue compartments of the uterus, and the immunohistochemical expression of nuclear estrogen receptor alpha (nERalpha), and nuclear progesterone receptor (nPR) were examined. Luminal epithelial cell hypertrophy was produced by all three compounds to a similar degree. 17beta-Estradiol produced an increase in uterine wet weight due to fluid imbibition over the 3-day period, and an increase in DNA synthesis in the endometrial stromal and myometrial compartments of the uterus, as measured by increased BrdU incorporation. Estradiol increased the expression of nERalpha and nPR in the myometrium with time and decreased nERalpha levels from the overexpressed levels in control ovariectomized rat luminal epithelial cells. Tamoxifen and toremifene caused a smaller increase in uterine weight and the BrdU labeling index in the endometrial stroma and myometrium than did estradiol, and they increased the expression of nERalpha and nPR in the myometrium. Tamoxifen and toremifene differed from estradiol in that they did not decrease the expression of nERalpha in the luminal epithelial cells of the uterus. The response of PR expression was the same for tamoxifen, toremifene, and estradiol, and was therefore considered to be the most reliable indication of an estrogen-agonist effect in this study. The ability to distinguish differential, compartmentalized effects for agonists of estrogen action in the uterus will allow a better risk assessment for new pharmaceuticals that are used as breast cancer chemotherapeutic agents, especially where their use may also be associated with an increased risk of uterine cancers, in particular.

New approaches to the quantitation of hypertrophy and hyperplasia in hepatomegaly

A histological method utilizing the optical dissector principle has been developed for determining the contribution of hypertrophy and hyperplasia to the hepatomegaly induced by the peroxisome proliferator gemfibrozil. The optical dissector is a technique derived from the 'new stereology' and has been used to estimate the number of hepatocyte nuclear profiles, that are present in a reference volume of tissue. The overall changes due to hypertrophy and hyperplasia in the rat liver after gemfibrozil treatment, did not reach significance, although the zonal hypertrophy change did. This indicated that although there was a 20% increase in liver weight with treatment, the hepatomegaly was caused by a combination of hypertrophy and hyperplasia, neither of which, on its own, was significantly different from the control values. The distinction of hyperplasia from hypertrophy, using a purely histological method, will be useful in assessing whether treatment related sustained hyperplasia is occurring in the liver.

The quantitative distinction of hyperplasia from hypertrophy in hepatomegaly induced in the rat liver by phenobarbital

A histological method utilizing the optical dissector principle has been developed for determining the absolute numbers of rat hepatocytes in the liver after treatment with phenobarbital (PB). The optical dissector is a technique derived from the "new stereology" used to measure the number of features, in this case hepatocyte nuclear profiles, that are present in a reference volume of tissue. The method has been applied to distinguish between the hepatomegaly that commonly occurs in rodents after treatment with chemicals, due to an increase in the number of cells caused by cell division (hyperplasia), rather than the size of cells (hypertrophy). In the case of PB treatment, the hepatomegaly was found to be partly due to hypertrophy and partly to hyperplasia after 2 weeks of treatment. While the increase in the absolute number of hepatocytes was not significant after 2 weeks, after 12 weeks of treatment with PB the number of hepatocytes was significantly increased, compared to the controls at that time point. PCNA labeling index measurements of liver hepatocytes confirmed that there was a significant increase in the growth fraction of hepatocytes during PB treatment. The induction of hyperplasia can be associated with an increased risk of eventual liver tumor formation, and the distinction of hyperplasia from hypertrophy, using a purely histological method, for the determination of increases in absolute hepatocyte cell numbers, will be useful in assessing whether treatment-related sustained hyperplasia is occurring in the liver, although this methodology could be applied to any organ.

Depletion of hepatocyte nuclear estrogen receptor expression is associated with promotion of tamoxifen induced GST-P foci to tumours in rat liver

The expression of hepatocyte nuclear estrogen receptor (ER) in putative preneoplastic foci, adenomas and carcinomas, induced by the rat liver carcinogen tamoxifen, has been examined immunohistologically. ER staining of normal rat liver shows between 30-50% of hepatocyte nuclei to be positive, depending on fixation. Depletion of ER was defined as <10% of cells in foci or tumours staining for nuclear ER. A proportion of all but the smallest glutathione-S-transferase, placental form (GST-P) expressing foci had depleted expression of nuclear ER. The percentage of GST-P expressing foci with depletion of nuclear ER increased with the size of the foci. The liver adenomas and carcinomas induced by tamoxifen showed a high incidence (90%) of depletion of ER. This suggests that abnormal expression of the ER is associated with the promotion of putative preneoplastic foci to adenomas and carcinomas in tamoxifen exposed rat livers. Dysfunction of the ER could contribute to selective continued stimulation of initiated cells that would be consistent with a role for modification of the ER in target cells and the promotion stage of liver cancer. Liver tumours induced by other carcinogens in both sexes of rat were also found to have a high incidence of ER depletion, indicating that this could be a general regulatory mechanism for rat liver tumour promotion, irrespective of the possible estrogen like action of individual carcinogens.

Iron promotes DEN initiated GST-P foci in rat liver

Diethylnitrosamine (DEN) was administered to rats as a single dose, which is known not to give rise to liver tumours without subsequent promotion. Iron dextran (Fe/Dex) was then administered parenterally to the animals, to induce iron overload. At 3 and 6 months after the final Fe/Dex treatments, livers were examined quantitatively for the numbers of the placental form of glutathione-S-transferase (GST-P) expressing foci, the area occupied by these foci and their size distribution. The results demonstrate that iron not only increased the number of foci after DEN initiation in the rat liver, but that the area occupied by these lesions increased significantly between 3 and 6 months after initiation. There is no evidence that iron increased the number of GST-P expressing foci present in rats not exposed to DEN. This indicates that iron did not act as an initiator in this rodent model of liver cancer. The increase in the area of the liver occupied by the foci in iron and DEN treated rats was due to an increase in the size of the foci, as well as to an increase in the number of foci. This is the first demonstration that iron can act as a promoter of DEN initiated hepatocytes. It also demonstrates that fibrogenesis is not an absolute requirement for the promotion, by iron, of liver foci in the rat, and that this could also be the case for iron overload in man. Iron may also act as a promoter of already initiated hepatocytes in the development of human liver cancer, as it does in the rat.

Method for determining whether the number of hepatocytes in rat liver is increased after treatment with the peroxisome proliferator gemfibrozil

A histological method has been developed for determining the absolute numbers of rodent hepatocytes after treatment with the hypolipodemic drug gemfibrozil. It can be applied to distinguish between the enlargement of the liver that commonly occurs in rodents after treatment with chemicals, due to changes in the size of cells (hypertrophy), rather than an increase in the number of cells caused by cell division (hyperplasia). In the case of gemfibrozil the liver enlargement was found to be partly due to hypertrophy and partly to hyperplasia. The induction of hyperplasia can be associated with an increased risk of eventual liver tumour formation, and the distinction of hypertrophy from hyperplasia using a purely histological method, for the determination of increases in hepatocyte cell numbers, will be useful in the assessment of compounds which cause liver enlargement that could precede neoplasia.

The role of cell death and cell proliferation in the promotion of rat liver tumours by tamoxifen

Administration of tamoxifen to rats results in liver tumours with a latency time that is dependent on the strain of rat used. Wistar and Lewis rats develop liver tumours more rapidly than Fischer rats. Significant increases in the number of apoptotic hepatocytes were found in the Wistar and Lewis strains of rats after they were fed tamoxifen for up to 6 months, but not in Fischer rats. By 6 months of exposure to tamoxifen there were liver tumours in the Wistar and Lewis rats, but not the Fischers. Sustained elevations of the PCNA labelling index were found in the livers of tamoxifen-treated Wistar and Lewis rats, over the first 6 months of tamoxifen treatment, but not Fischers. It is proposed that sustained cell death by apoptosis may play a role in the mechanism of promotion of tamoxifen-induced liver tumours, by causing liver hyperplasia. To support this concept it has been shown that cyloheximide, which causes apoptosis but not necrosis in the rat liver, causes DNA synthesis and cell division in hepatocytes.

Tamoxifen associated uterine pathology in rodents: relevance to women

Rats administered tamoxifen for 3 months and then returned to a basal diet developed an increase in uterine weight for up to 9 months after tamoxifen exposure. Stereological analysis of the tamoxifen exposed rat uteri showed that there was a significant increase in the amount of uterine myometrium, for a further 9 months, subsequent to the discontinuation of tamoxifen. A low incidence of myometrial proliferations (deciduomas) and uterine tumours was found at the conclusion of the study (20 months). In contrast, continuous administration of tamoxifen to mice for 24 months produced hyperplasia of the uterine endometrial epithelium and atrophy of the myometrium for the first 3 months, followed by atrophy of both the endometrium and myometrium for the remaining 21 months of the study. No uterine tumours were found in mice treated with tamoxifen for 2 years. The use of stereological analysis on interim sacrifice rodent uteri indicated that sustained uterine tissue compartment effects can occur, with either the continuous administration of tamoxifen, or after its discontinuation. Tamoxifen can have an agonist and antagonist like effect on oestrogen activity in different tissue compartments of the mouse uterus, over the same time period. The particular relevance of the finding of uterine proliferation and atrophy in the rodent studies with tamoxifen is discussed with regard to women taking this drug.

Torsade de pointes associated with Astemizole overdose treated with magnesium sulfate

Astemizole (Hismanal-Janssen, New Brunswick, NJ) is a nonsedating antihistamine that has the advantage of a once-daily dosage schedule. This article reports the case of a 14-year-old female who intentionally ingested 270 mg of Astemizole and developed torsade de pointes, a form of polymorphic ventricular tachycardia that is associated with prolongation of the QTc interval. She was successfully treated with magnesium sulfate infusion and had an uneventful recovery over a period of 36 hours. This case illustrates that Astemizole overdose is not benign and should be considered in the differential diagnosis of ventricular tachyarrhythmias. Use of high-dose Astemizole may not be advisable for patients who are at risk for prolongation of the QTc interval.

Occupational repetition strain injuries. Guidelines for diagnosis and management

Occupational repetition strain injuries (RSI) are a major, unchecked source of disability in industry and commerce, and have considerable social and economic consequences. The long-term morbidity associated with these injuries is preventable, but a coordinated approach to awareness, diagnosis, management, and prevention has been lacking. Confusing diagnostic terminology on medical certificates makes it difficult to obtain accurate data on the incidence and prevalence of different types of repetition injury. The terminology in use at present includes RSI, "tenosynovitis" and "overuse injury". Uniformity of diagnosis on an anatomical basis in relation to repetition or static load would greatly assist in epidemiological study, and improve notification and the impact of prevention programmes. Therefore, the Occupational Repetition Strain Injuries Advisory Committee, which was convened by the Division of Occupational Health, New South Wales Government Department of Industrial Relations, has prepared a set of guidelines for the diagnosis and management of these injuries.