Total hip arthroplasty in patients with neuromuscular imbalance.

Patients with neuromuscular imbalance who require total hip arthroplasty (THA) present particular technical problems due to altered anatomy, abnormal bone stock, muscular imbalance and problems of rehabilitation. In this systematic review, we studied articles dealing with THA in patients with neuromuscular imbalance, published before April 2017. We recorded the demographics of the patients and the type of neuromuscular pathology, the indication for surgery, surgical approach, concomitant soft-tissue releases, the type of implant and bearing, pain and functional outcome as well as complications and survival. Recent advances in THA technology allow for successful outcomes in these patients. Our review suggests excellent benefits for pain relief and good functional outcome might be expected with a modest risk of complication. Cite this article: Bone Joint J 2018;100-B(1 Supple A):17-21.

Trunnion corrosion: what surgeons need to know in 2018.

AIMS: To present a surgically relevant update of trunnionosis. MATERIALS AND METHODS: Systematic review performed April 2017. RESULTS: Trunnionosis accounts for approximately 2% of the revision total hip arthroplasty (THA) burden. Thinner (reduced flexural rigidity) and shorter trunnions (reduced contact area at the taper junction) may contribute to mechanically assisted corrosion, exacerbated by high offset implants. The contribution of large heads and mixed metallurgy is discussed. CONCLUSION: Identifying causative risk factors is challenging due to the multifactorial nature of this problem. Cite this article: Bone Joint J 2018;100-B(1 Supple A):44-9.

Revision for adverse local tissue reaction following metal-on-polyethylene total hip arthroplasty is associated with a high risk of early major complications.

Aims: Fretting and corrosion at the modular head/neck junction, known as trunnionosis, in total hip arthroplasty (THA) is a cause of adverse reaction to metal debris (ARMD). We describe the outcome of revision of metal-on-polyethylene (MoP) THA for ARMD due to trunnionosis with emphasis on the risk of major complications. Patients and Methods: A total of 36 patients with a MoP THA who underwent revision for ARMD due to trunnionosis were identified. Three were excluded as their revision had been to another metal head. The remaining 33 were revised to a ceramic head with a titanium sleeve. We describe the presentation, revision findings, and risk of complications in these patients. Results: The patients presented with pain, swelling, stiffness, or instability and an inflammatory mass was confirmed radiologically. Macroscopic material deposition on the trunnion was seen in all patients, associated with ARMD. Following revision, six (18.2%) dislocated, requiring further revision in four. Three (9.1%) developed a deep infection and six (18.2%) had significant persistent pain without an obvious cause. One developed a femoral artery thrombosis after excision of an iliofemoral pseudotumor, requiring a thrombectomy. Conclusion: The risk of serious complications following revision MoP THA for ARMD associated with trunnionosis is high. In the presence of extensive tissue damage, a constrained liner or dual mobility construct is recommended in these patients. Cite this article: Bone Joint J 2018;100-B:720-4.

Predictors of quality of life outcomes after revision total hip replacement.

A prospective cohort of 222 patients who underwent revision hip replacement between April 2001 and March 2004 was evaluated to determine predictors of function, pain and activity level between one and two years post-operatively, and to define quality of life outcomes using validated patient reported outcome tools. Predictive models were developed and proportional odds regression analyses were performed to identify factors that predict quality of life outcomes at one and two years post-operatively. The dependent outcome variables were the Western Ontario and McMaster Osteoarthritis Index (WOMAC) function and pain scores, and University of California Los Angeles activity scores. The independent variables included patient demographics, operative factors, and objective quality of life parameters, including pre-operative WOMAC, and the Short Form-12 mental component score. There was a significant improvement (t-test, p < 0.001) in all patient quality of life scores. In the predictive model, factors predictive of improved function (original regression analyses, p < 0.05) included a higher pre-operative WOMAC function score (p < 0.001), age between 60 and 70 years (p < 0.037), male gender (p = 0.017), lower Charnley class (p < 0.001) and aseptic loosening being the indication for revision (p < 0.003). Using the WOMAC pain score as an outcome variable, factors predictive of improvement included the pre-operative WOMAC function score (p = 0.001), age between 60 and 70 years (p = 0.004), male gender (p = 0.005), lower Charnley class (p = 0.001) and no previous revision procedure (p = 0.023). The pre-operative WOMAC function score (p = 0.001), the indication for the operation (p = 0.007), and the operating surgeon (p = 0.008) were significant predictors of the activity assessment at follow-up. Predictors of quality of life outcomes after revision hip replacement were established. Although some patient-specific and surgery-specific variables were important, age, gender, Charnley class and pre-operative WOMAC function score had the most robust associations with outcome.

Comparative repeatability of guide-pin axis positioning in computer-assisted and manual femoral head resurfacing arthroplasty.

The orientation of the femoral component in hip resurfacing arthroplasty affects the likelihood of loosening and fracture. Computer-assisted surgery has been shown to improve significantly the surgeon's ability to achieve a desired position and orientation; nevertheless, both bias and variability in positioning remain and can potentially be improved. The authors recently developed a computer-assisted surgical (CAS) technique to guide the placement of the pin used in femoral head resurfacing arthroplasty and showed that it produced significantly less variation than a typical manual technique in varus/valgus placement relative to a preoperatively determined surgical plan while taking a comparable amount of time. In the present study, the repeatability of both the CAS and manual techniques is evaluated in order to estimate the relative contributions to overall variability of surgical technique (CAS versus manual), surgeon experience (novice versus experienced), and other sources of variability (e.g. across specimens and across surgeons). This will enable further improvements in the accuracy of CAS techniques. Three residents/fellows new to femoral head resurfacing and three experienced hip arthroplasty surgeons performed 20-30 repetitions of each of the CAS and manual techniques on at least one of four cadaveric femur specimens. The CAS system had markedly better repeatability (1.2 degrees) in varus/valgus placement relative to the manual technique (2.8 degrees), slightly worse repeatability in version (4.4 degrees versus 3.2 degrees), markedly better repeatability in mid-neck placement (0.7 mm versus 2.5 mm), no significant dependence on surgeon skill level (in contrast to the manual technique), and took significantly less time (50 s versus 123 s). Proposed improvements to the version measurement process showed potential for reducing the standard deviation by almost two thirds. This study supports the use of CAS for femoral head resurfacing as it is quicker than the manual technique, independent of surgeon experience, and demonstrates improved repeatability.

Porous tantalum uncemented acetabular components in revision total hip arthroplasty: a minimum ten-year clinical, radiological and quality of life outcome study.

AIMS: Reconstruction of the acetabulum after failed total hip arthroplasty (THA) can be a surgical challenge in the presence of severe bone loss. We report the long-term survival of a porous tantalum revision acetabular component, its radiological appearance and quality of life outcomes. PATIENTS AND METHODS: We reviewed the results of 46 patients who had undergone revision of a failed acetabular component with a Paprosky II or III bone defect and reconstruction with a hemispherical, tantalum acetabular component, supplementary screws and a cemented polyethylene liner. RESULTS: After a minimum follow-up of ten years (ten to 12), the survivorship of the porous tantalum acetabular component was 96%, with further revision of the acetabular component as the end point. The ten-year survivorship, with hip revision for any reason as the end point, was 92%. We noted excellent pain relief (mean Western Ontario and McMaster Universities Arthritis Index (WOMAC) score pain 92.6, (40 to 100)) and good functional outcomes (mean WOMAC function 90.3 (30.9 to 100), mean University of California Los Angeles activity scale 5 (2 to 10)) and generic quality of life measures (mean Short Form-12 (SF-12) physical component 48.3 (18.1 to 56.8), mean SF-12 mental component 56.7 (32.9 to 70.3)). Patient satisfaction with pain relief, function and return to recreational activities were excellent. TAKE HOME MESSAGE: Uncemented acetabular reconstruction using a tantalum acetabular component gives excellent clinical and quality of life outcomes at a minimum follow-up of ten years. Cite this article: Bone Joint J 2016;98-B:767-71.

Deep infection after hip arthroplasty: staying current with change.

Periprosthetic joint infection (PJI) complicates between 0.5% and 1.2% primary total hip arthroplasties (THAs) and may have devastating consequences. The traditional assessment of patients suffering from PJI has involved the serological study of inflammatory markers and microbiological analysis of samples obtained from the joint space. Treatment has involved debridement and revision arthroplasty performed in either one or two stages. We present an update on the burden of PJI, strategies for its diagnosis and treatment, the challenge of resistant organisms and the need for definitive evidence to guide the treatment of PJI after THA.

Modular tapered titanium stems in revision arthroplasty of the hip: The Risk and Causes of Stem Fracture.

Tapered fluted titanium stems are increasingly used for femoral revision arthroplasty. They are available in modular and non-modular forms. Modularity has advantages when the bone loss is severe, the proximal femur is mis shapen or the surgeon is unfamiliar with the implant, but it introduces the risk of fracture of the stem at the junction between it and the proximal body segment. For that reason, and while awaiting intermediate-term results of more recently introduced designs of this junction, non-modularity has attracted attention, at least for straightforward revision cases. We review the risks and causes of fracture of tapered titanium modular revision stems and present an argument in favour of the more selective use of modular designs.

Periprosthetic fractures associated with total knee arthroplasty: an update.

Fractures around total knee arthroplasties pose a significant surgical challenge. Most can be managed with osteosynthesis and salvage of the replacement. The techniques of fixation of these fractures and revision surgery have evolved and so has the assessment of outcome. This specialty update summarises the current evidence for the classification, methods of fixation, revision surgery and outcomes of the management of periprosthetic fractures associated with total knee arthroplasty. Cite this article: Bone Joint J 2016;98-B:1489-96.

Delayed dislocation following metal-on-polyethylene arthroplasty of the hip due to 'silent' trunnion corrosion.

AIMS: We present a case series of ten metal-on-polyethylene total hip arthroplasties (MoP THAs) with delayed dislocation associated with unrecognised adverse local tissue reaction due to corrosion at the trunnion and pseudotumour formation. METHODS: The diagnosis was not suspected in nine of the ten patients (six female/four male; mean age 66 years), despite treatment in a specialist unit (mean time from index surgery to revision was 58 months, 36 to 84). It was identified at revision surgery and subsequently confirmed by histological examination of resected tissue. Pre-operative assessment and culture results ruled out infection. A variety of treatment strategies were used, including resection of the pseudotumour and efforts to avoid recurrent dislocation. RESULTS: The rate of complications was high and included three deep infections, two patients with recurrent dislocation, and one recurrent pseudotumour. CONCLUSION: This series (mean follow-up of 76 months following index procedure and 19 months following revision THA) demonstrates that pseudotumour is an infrequent but important contributor to delayed instability following MoP THA. It is easy to overlook in the differential diagnosis, especially if the alignment of the components is less than optimal, leading to an assumption that malalignment is the cause of the dislocation. The instability is likely to be multifactorial and the revision surgery is complex. TAKE HOME MESSAGE: Due to the high complication rate associated with revision in this cohort, the diagnosis should be borne in mind when counselling patients regarding the risks of revision surgery.

Adverse local tissue reactions in metal-on-polyethylene total hip arthroplasty due to trunnion corrosion: the risk of misdiagnosis.

Adverse reaction to wear and corrosion debris is a cause for concern in total hip arthroplasty (THA). Modular junctions are a potential source of such wear products and are associated with secondary pseudotumour formation. We present a consecutive series of 17 patients treated at our unit for this complication following metal-on-highly cross-linked polyethylene (MoP) THA. We emphasise the risk of misdiagnosis as infection, and present the aggregate laboratory results and pathological findings in this series. The clinical presentation was pain, swelling or instability. Solid, cystic and mixed soft-tissue lesions were noted on imaging and confirmed intra-operatively. Corrosion at the head-neck junction was noted in all cases. No bacteria were isolated on multiple pre- and intra-operative samples yet the mean erythrocyte sedimentation rate was 49 (9 to 100) and C-reactive protein 32 (0.6 to 106) and stromal polymorphonuclear cell counts were noted in nine cases. Adverse soft-tissue reactions can occur in MoP THA owing to corrosion products released from the head-neck junction. The diagnosis should be carefully considered when investigating pain after THA. This may avoid the misdiagnosis of periprosthetic infection with an unidentified organism and mitigate the unnecessary management of these cases with complete single- or two-stage exchange.

Effects of MK-801 on DNA synthesis in neonatal rat brain regions under normoxic and hypoxic conditions.

Global metabolic insults such as ischemia/hypoxia, damage neural cells through release of excitatory amino acids and their subsequent actions at the N-methyl-D-aspartate (NMDA) receptor. NMDA receptors are highly expressed in neonatal rat brain, and the current study examines the effects of receptor blockade with MK-801 on DNA synthesis under normoxic and hypoxic conditions. At one day of age, hypoxia alone caused a decrease in [3H]thymidine incorporation into DNA throughout the brain, whereas MK-801 alone decreased incorporation selectively in regions known to be enriched in NMDA receptors. MK-801 afforded no protection from hypoxia and instead exacerbated the effects of hypoxia in the cerebellum. At 8 days of age, hypoxia alone or MK-801 alone still produced the same patterns of inhibition of DNA synthesis, but MK-801 neither prevented nor exacerbated the effects of hypoxia; animals receiving MK-801 showed a significant incidence of hypoxia-induced mortality. These data suggest that excitatory actions exerted at the NMDA receptor serve to maintain cell replication in neonatal brain and, as distinct from the situation for excitatory amino acid-induced cell death, these receptors do not participate in adverse effects of hypoxia on DNA synthesis.

Dual control of DNA synthesis by alpha- and beta-adrenergic mechanisms in normoxic and hypoxic neonatal rat brain.

To examine how catecholamines influence cell replication in the developing brain, we examined regional [3H]thymidine incorporation into DNA after acute challenge with an alpha-adrenergic blocking agent (phenoxybenzamine) or a beta-blocker (propranolol). Phenoxybenzamine inhibited DNA synthesis in 1-day-old rat pups but the effect was less pronounced at 8 days; regional differences corresponded to transient expression of alpha-receptors and their subsequent maturational decline. Propranolol given at 1 day of age exerted a regionally selective, promotional effect on DNA synthesis; in contrast, at 8 days, propranolol inhibited DNA synthesis in all brain regions. Propranolol, but not phenoxybenzamine, also exacerbated the reduction in DNA synthesis caused by neonatal hypoxia, and again the effect was limited to the 1-day-old group. These results indicate that catecholamines exert a dual action on DNA synthesis; the effects are dependent upon maturational profiles of specific receptor populations which are either transiently expressed or which couple to cell replication only during a critical period.

Treatment of infection associated with segmental bone loss in the proximal part of the femur in two stages with use of an antibiotic-loaded interval prosthesis.

Treatment of an infection at the site of a total hip replacement associated with extensive loss of the proximal part of the femur is a challenging problem. In the present preliminary report, we describe the results after use of a prosthesis of antibiotic-loaded acrylic cement (PROSTALAC) in thirty such hips. The purpose of the prosthesis, which acts as an internal splint, is to maintain the length of the femur as well as the range of motion of the joint and the mobility of the patient between stages. A local level of antibiotics is maintained by the antibiotic-coated surface. A PROSTALAC with a cement-on-cement articulation was used in the first fifteen hips (Group I) in the study, and a custom metal-on-polyethylene articulating PROSTALAC was inserted in the subsequent fifteen hips (Group II). One patient who had a recurrent infection was managed with a second two-stage exchange and was included in both groups. Between stages, the average limb-length discrepancy was twenty-five millimeters despite a loss of more than 25 per cent of the femur in nineteen limbs. Sixteen patients were discharged home and seven, to a community hospital between stages. Six patients in Group I and only one in Group II were hospitalized for the entire course of treatment. The total duration of hospitalization for both stages averaged thirty-eight days. Twenty-eight patients were mobile even though they did not bear weight on the involved limb between stages: three patients used a cane, fifteen used crutches, and ten used a walker. Twenty-six patients reported no, slight, or moderate pain in the thigh, groin, or buttock between stages. The average Harris hip score before the first stage of the operation was 23 points (range, 0 to 63 points), which improved to 74 points (range, 40 to 91 points) at an average of forty-seven months (range, twenty-four to 114 months) postoperatively. Two patients died of unrelated causes before two years (the minimum follow-up period) had elapsed and were excluded from the final analysis; they had no evidence of recurrent infection. Of the remaining twenty-eight hips, twenty-seven (96 per cent) had no evidence of infection at the most recent follow-up examination.

Prospective analysis of preoperative and intraoperative investigations for the diagnosis of infection at the sites of two hundred and two revision total hip arthroplasties.

BACKGROUND: Total hip arthroplasty is a commonly performed procedure in the United States and Canada that is associated with a definite risk of postoperative infection. Moreover, diagnosing an infection after total hip arthroplasty can present a challenge as there are no preoperative tests that are consistently sensitive and specific for infection in patients who need a revision arthroplasty. The present prospective study was performed to evaluate a variety of investigations for the diagnosis of infection at the site of a previous arthroplasty in order to determine if any combination of diagnostic studies could be used to determine which patients are at risk for a postoperative wound infection. METHODS: We prospectively analyzed the preoperative and intraoperative investigations used for the diagnosis of infection in 178 patients who had a total of 202 revision hip replacements. Clinical data were collected preoperatively. Investigations to determine the presence or absence of infection included a white blood-cell count, measurement of the erythrocyte sedimentation rate, measurement of the level of C-reactive protein, preoperative aspiration of the joint, intraoperative gram-staining and culture of periprosthetic tissue, a white blood-cell count in synovial fluid, and examination of intraoperative frozen sections. Frozen sections were analyzed in a blinded fashion without knowledge of clinical or laboratory data. Patients receiving antibiotics at the time of aspiration or collection of specimens for intraoperative culture were excluded from the analysis of those investigations, regardless of the results of the cultures. A positive result (suggestive of infection) was clearly defined for each of the investigations. RESULTS: Thirty-five hips (17 percent) were determined to be infected on the basis of clinical findings and positive results, according to the defined criteria, of investigations. With inflammatory conditions excluded, the sensitivity, specificity, positive predictive value, and negative predictive value were 0.82, 0.85, 0.58, and 0.95, respectively, for the erythrocyte sedimentation rate and 0.96, 0.92, 0.74, and 0.99, respectively, for the level of C-reactive protein. All patients who had a periprosthetic infection had an elevated erythrocyte sedimentation rate or level of C-reactive protein, but not always both. When patients who were receiving antibiotics were excluded, the results of aspiration of the joint were 0.86 for sensitivity, 0.94 for specificity, 0.67 for the positive predictive value, and 0.98 for the negative predictive value. Intraoperative studies revealed sensitivities, specificities, positive predictive values, and negative predictive values of 0.19, 0.98, 0.63, and 0.89, respectively, for gram-staining of specimens of the most inflamed-appearing tissue; 0.36, 0.99, 0.91, and 0.90, respectively, for the white bloodcell count in synovial fluid; and 0.89, 0.85, 0.52, and 0.98, respectively, for a neutrophil count in synovial fluid of more than 80 percent. The sensitivity, specificity, positive predictive value, and negative predictive value were 0.80, 0.94, 0.74, and 0.96, respectively, for the frozen sections and 0.94, 0.97, 0.77, and 0.99, respectively, for the intraoperative cultures. CONCLUSIONS: The combination of a normal erythrocyte sedimentation rate and C-reactive protein level is reliable for predicting the absence of infection. Aspiration should be used when the erythrocyte sedimentation rate or the C-reactive protein level is elevated or when a clinical suspicion of infection remains. We found the gram stain to be unreliable. Examination of intraoperative frozen sections is useful in equivocal cases or when hematological markers may be falsely elevated because of an inflammatory or other condition.

J. Edouard Samson Address: the autonomic nerve supply of bone. An experimental study of the intraosseous adrenergic nervi vasorum in the rabbit.

The anatomy of the autonomic sympathetic vasomotor nerve supply of bone was studied in rabbits by methods of histochemistry, and fluorescent and electron microscopy. Our observations show that the intraosseous vessels are richly supplied by adrenergic nerves. The large primary nerves are located on or about the surface of the vessel; the medium sized secondary nerves spiral around the long axis of vessels lying more deeply in the tunica adventitia; and the fine tertiary nerves form a rich plexus at the outer area of the tunica media. The tertiary nerves have various structures which probably contain neurotransmitter substance--that is, noradrenaline--and function as neuro-vasomuscular synapses. The sympathetic nerve supply of bone originates from the appropriate ganglion, and in the case of the tibial diaphysis it descends through the sciatic nerve and thereafter mainly through the medial popliteal nerve and enters the bone alongside the nutrient artery.

Allograft impaction and cement penetration after revision hip replacement. A histomorphometric analysis in the cadaver femur.

We studied various aspects of graft impaction and penetration of cement in an experimental model. Cancellous bone was removed proximally and local diaphyseal lytic defects were simulated in six human cadaver femora. After impaction grafting the specimens were sectioned and prepared for histomorphometric analysis. The porosity of the graft was lowest in Gruen zone 4 (52%) and highest in Gruen zone 1 (76%). At the levels of Gruen zones 6 and 2 the entire cross-section was almost filled with cement. Cement sometimes reached the endosteal surface in other Gruen zones. The mean peak impaction forces exerted with the impactors were negatively correlated with the porosity of the graft.

Structural proximal femoral allografts for failed total hip replacements: a minimum review of five years.

There are few medium- and long-term data on the outcome of the use of proximal femoral structural allografts in revision hip arthroplasty. This is a study of a consecutive series of 40 proximal femoral allografts performed for failed total hip replacements using the same technique with a minimum follow-up of five years (mean 8.8 years; range 5 to 11.5 years). In all cases the stem was cemented into both the allograft and the host femur. The proximal femur of the host was resected in 37 cases. There were four early revisions (10%), two for infection, one for nonunion of the allograft-host junction, and one for allograft resorption noted at the time of revision of a failed acetabular reconstruction. Junctional nonunion was seen in three patients (8%), two of whom were managed successfully by bone grafting, and bone grafting and plating respectively. Instability was observed in four (10%). Trochanteric nonunion was seen in 18 patients (46%) and trochanteric escape in ten of these (27%). The mean Harris hip score improved from 39 to 79. Severe resorption involving the full thickness of the allograft was seen in seven patients (17.5%). This progressed rapidly and silently, but has yet to cause failure of any of the reconstructions. Profound resorption of the allograft may be related to a combination of factors, including a slow form of immune rejection, stress shielding and resorption due to mechanical disuse with solid cemented distal fixation, and the absence of any masking or protective effect which may be provided by the retention of the bivalved host bone as a vascularised onlay autograft. Although continued surveillance is warranted, the very good medium-term clinical results justify the continued use of structural allografts for failed total hip replacements with severe loss of proximal femoral bone.

CT evaluation of periacetabular osteotomies.

We have previously described a simple and reproducible three-dimensional technique of CT for the measurement of the cover of the femoral head in acetabular dysplasia in adults. We now describe the application of this technique in ten patients with symptomatic dysplasia to assess the degree and direction of dysplasia and to measure the cover obtained at acetabular osteotomy. The indices obtained gave a useful indication of the degree and direction of the dysplasia and confirmed which components had been used most efficiently to achieve cover. The information is easily presented in graphical form and gives a clearer indication of the cover obtained than the indices derived from plain radiographs.

The cement mantle in femoral impaction allografting. A comparison of three systems from four centres.

An analysis of the cement mantle obtained with the Exeter impaction allografting system at one centre showed that it was either deficient or absent in almost 47% of Gruen zones. We therefore examined the mantle obtained using this system at another hospital and compared the results with those from the CPT and Harris Precoat Systems at other centres. The surgical indications for the procedure and the patient details were broadly similar in all four hospitals. There was some variation in the frequency of use of cortical strut allografts, cerclage wires and wire mesh to supplement the impaction allograft. Analysis of the cement mantles showed that when uncertain Gruen zones were excluded, the incidence of zones with areas of absence or deficiency of the cement was 47% and 50%, respectively, for the two centres using the Exeter system, 21% for the CPT system and 18% for the Harris Precoat system. We measured the difference in size between the proximal allograft impactors and the definitive prosthesis for each system. The Exeter system impactors are shorter than the definitive prosthesis and taper sharply so that the cavity created is inadequate, especially distally. The CPT proximal impactors are considerably longer than the definitive prosthesis and are designed to give a mantle of approximately 2 mm medially and laterally and 1.5 mm anteriorly and posteriorly. The Harris Precoat proximal impactors allow for a mantle with a circumference of 0.75 mm in the smaller sizes and 1 mm in the larger. Many reports link the longevity of a cemented implant to the adequacy of the cement mantle. For this reason, femoral impaction systems require careful design to achieve a cement mantle which is uninterrupted in its length and adequate in its thickness. Our results suggest that some current systems require modification.