Bridging massive acetabular defects with the triflange cup: 2- to 9-year results.

An unresolved issue in total hip arthroplasty is acetabular reconstruction when there is bone loss that results in pelvic discontinuity, that involves radiation-compromised bone stock, or that is significant enough to exceed the limits of jumbo hemispherical cups. Achieving pain relief and initial and long-term implant stability on host bone are the major goals of this type of reconstruction. Seventy-eight hips in 76 patients in whom a large acetabular defect was bridged using a custom-designed, flanged component were reviewed retrospectively. The preoperative deficiency was classified as a combined deficiency in 39 hips and as a pelvic discontinuity in the other 39 hips. Six patients died before a minimum 2 years followup. With five patients considered lost to followup, there were 67 hips in 65 patients with an average followup of 53 months (range, 24-107 months). No Triflange Cup has been removed. Harris hip scores improved from a preoperative mean of 33.3 points to a postoperative mean of 82.1 points. Radiographically there are two patients with incompletely healed discontinuities but both are asymptomatic. Re-operation for recurrent dislocation occurred in six patients (7.8%). The Triflange Cup offers an alternative method of repair that reliably provides pain relief, initial implant stability, potential long-term implant stability, and pelvic stability in cases of discontinuity.

Clinical experience with a modular noncemented femoral component in revision total hip arthroplasty: 4- to 7-year results.

A series of 163 revision total hip arthroplasties performed using a modular proximally porous-coated device was reviewed. Twenty patients died before achieving minimum follow-up, and 13 hips with Paprosky type IV femora were excluded. One patient was lost to follow-up. Minimum 4-year clinical data on the remaining 129 hips showed an improvement in modified Harris hip scores, from an average of 47.7 to 87.5. Spot welds at the sleeve-bone interface were found in 83 of the 102 hips with minimum radiographic follow-up. The aseptic failure rate was 2.9%; these hips showed progressive subsidence, with 1 resulting in the only repeat revision in the series. Three hips had osteolytic lesions of <5 mm; none threatened implant stability. There were no complications related to modularity.

Primary total hip arthroplasty with use of the modular S-ROM prosthesis. Four to seven-year clinical and radiographic results.

BACKGROUND: A multicenter retrospective study was conducted to determine the clinical and radiographic results of primary total hip arthroplasty with insertion of the S-ROM modular femoral stem without cement in a series of patients who had been followed for four to seven years. Four centers participated in the study, with one contributing surgeon at each center. METHODS: Two hundred and eight consecutive patients who had a total hip arthroplasty with implantation of the S-ROM femoral prosthesis at one of the four centers during the study period were identified. Twenty-nine patients were lost to follow-up or had incomplete radiographic data, and twenty patients died from causes unrelated to the index arthroplasty. The remaining 159 patients formed the basis of this study. Sixteen of these patients had a bilateral procedure, resulting in 175 hips with complete clinical and radiographic data. The average age of the patients at the time of the index operation was fifty-nine years (range, twenty-two to ninety-three years). The duration of clinical follow-up averaged 5.3 years (range, four to 7.8 years), and the duration of radiographic follow-up averaged 4.9 years (range, four to 7.3 years). RESULTS: One patient (0.6 percent) had a failed femoral component, which was evidenced by progressive subsidence and lack of bone ingrowth. In addition, two patients (1 percent) had a revision of the acetabular component. The average Harris hip score increased from 35 points (range, 10 to 76 points) preoperatively to 91 points (range, 52 to 100 points) at the most recent follow-up examination. The radiographic evaluation revealed that 172 hips (98 percent) had stable bone ingrowth, two hips (1 percent) had stable fibrous ingrowth, and one hip (0.6 percent) had unstable fibrous ingrowth. Periprosthetic osteolytic lesions were noted in twelve hips (7 percent). The lesions were observed in the femur in eight hips, in the acetabulum in two hips, and in both the femur and the acetabulum in two hips. All femoral osteolytic lesions were localized within the greater trochanter or the proximal-medial portion of the femoral neck. No osteolytic lesions were evident distal to the stem-sleeve junction. CONCLUSIONS: Use of the modular S-ROM femoral prosthesis yielded excellent intermediate-term outcomes with respect to standard radiographic and clinical criteria. The issue regarding the theoretical increase in the rate of osteolysis due to metal debris generated at the modular femoral stem-sleeve junction was specifically addressed. We found that the rate of osteolysis in this series was not notably higher than that in other series reported in the orthopaedic literature. Although many possible factors may influence the rate of osteolysis in total hip arthroplasty, this finding suggests that the potential increase in osteolysis theoretically associated with this modular femoral implant was not observed at intermediate-term follow-up. Although longer follow-up is warranted so that the potential for osteolysis can be evaluated fully, no osteolytic lesions were evident distal to the stem-sleeve interface at the time of intermediate-term follow-up. This finding suggests that there is a circumferential seal at the modular junction of the stem that prevents the distal egress of wear debris.

Reconstruction of the deficient acetabulum with an oblong prosthesis: three- to seven-year results.

A retrospective review was conducted to determine the intermediate-term results of a noncustomized, oblong, porous-coated, cementless, acetabular component designed to obtain stability on host bone while maintaining an anatomic hip center. The clinical and radiographic results were reviewed in 18 patients (3 primary, 15 revision). All patients had substantial acetabular rim defects before reconstruction with the Johnson and Johnson E-15 or E-25 oblong components. The average follow-up was 4.5 years (range, 3.4-6.9 years), with an average postoperative Harris Hip Score of 91 points. Radiographic analysis revealed no prosthetic migration and near anatomic restoration of the hip center.

The spinal nail: a new implant for short-segment anterior instrumentation of the thoracolumbar spine.

The biomechanics of a new spinal implant were evaluated and its dependence on an anterior strut graft was determined. Six fresh-frozen adult porcine spines were used. An L3 corpectomy was created. The spinal nail was inserted intraosseously into the middle column of the L2-L4 vertebral bodies in a trough. Implant drill holes were made for proximal and distal locking bolts in L2 and L4. A locking plate bridged the L2 and L4 trough and anchored the exposed ends of the locking bolts. Testing was performed in axial compression, torsion, and flexion. The axial and torsional stability of the spine instrumented with the spinal nail are similar to results with other devices when used with anterior strut grafting. The axial and flexural stiffnesses of the instrumented spine are independent of strut grafting. This study suggests that this device may be useful for reconstruction of the anterior spine because of instability.

Fusobacterium osteomyelitis and pyarthrosis: a classic case of Lemierre's syndrome.

Lemierre's syndrome, a systemic anaerobic infection caused by Fusobacterium necrophorum, is characterized by an acute oropharyngeal infection, septic thrombophlebitis of the internal jugular vein, sepsis, and multiple metastatic infections. It commonly leads to septic arthritis and occasionally to osteomyelitis. In the preantibiotic era, this infection was nearly universally fatal. Today it still poses a potentially grave threat to the young patients affected. Prompt recognition with appropriate debridement and antibiotic treatment results in complete recovery in most cases. We report a case of anaerobic septic arthritis and multifocal acute hematogenous osteomyelitis as part of a classic presentation of Lemierre's syndrome.

Heterogeneous survival rates for isolated skeletal metastases from melanoma.

In this study, the authors examine the survivorship of individuals who constitute the small subset of patients with Stage IV melanoma who present with their first and only detectable metastasis to the skeleton. One thousand two hundred six patients were identified with primary melanoma at the authors' institution since 1962. There were 14 patients with isolated (solitary) skeletal metastases. Survival was calculated by Kaplan-Meier technique. The survival rate for any individual with an isolated metastasis to the axial skeleton was 0. Three of 8 patients with melanoma metastases to the appendicular skeleton are alive at 18, 25, and 52 months after Stage IV detection. A statistically significant prolonged latency period (initial diagnosis to Stage IV) in the appendicular group compared with the axial group contributed to their significant survival rate advantage. The melanoma literature strongly supports the complete resection of soft tissue metastatic foci. These data support this concept and extend it to include isolated skeletal metastases. The mechanisms by which axial and appendicular skeletal metastases occur are significantly different. This difference manifests itself as a survival advantage for the appendicular group and warrants an aggressive surgical approach for these individuals.

Renal hemodynamic actions of lipoxins in rats: a comparative physiological study.

Interactions between either the arachidonate 5-lipoxygenase (5-LO) and 15-LO or 5-LO and 12-LO can lead to the formation of lipoxins. Although the functional significance of lipoxygenase products of arachidonic acid has been recognized increasingly in glomerular inflammation, less is known regarding the specific effects of lipoxins on renal hemodynamics. Here, we examine the renal actions of lipoxin (LX) A4, LXB4, and, the recently identified 7-cis-11-trans-LXA4, which were administered into the renal artery of the euvolemic male Munich-Wistar rat. LXA4 caused increases in renal plasma flow (RPF) and glomerular filtration rate (GFR) in a dose-dependent manner. These effects were reversed during cyclooxygenase inhibition. LXB4 decreased both RPF and GFR, and its mode of action was independent of cyclooxygenase activity. 7-cis-11-trans-LXA4 decreased RPF and GFR, which effects were abolished during systemic infusion of the leukotriene D4 receptor antagonist SKF 104353. Results indicate that each of these lipoxins displays distinct hemodynamic effects via a specific mode of action on the renal vasculature of rats. Moreover, they suggest mechanisms whereby lipoxins may participate in the changes of renal hemodynamics that occur during glomerular inflammatory processes.

Role of dialysable solutes in the mediation of uremic encephalopathy in the rat.

This study addresses mechanisms of the clinical, encephalopathic uremic illness and its suppression by dialysis. Renoprival rats were treated with peritoneal dialysis (8 exchanges per day, 30 min dwell), or untreated (attrition group), and their EEG's were automatically sampled overnight and subjected to power spectrum analysis as an index of encephalopathy. As in man the background rhythm of the quantified EEG (Q.EEG) in the attrition group slowed with time as extracellular fluid composition became increasingly abnormal; these changes were normalized by therapeutic dialysis (TD) using standard, commercial dialysate. However, Q.EEG slowing was only partially normalized by solute-specific dialysis using "mock uremic dialysate" (M-UD), prepared from laboratory chemicals to equal plasma concentrations in preterminal uremic rats of urea, creatinine, potassium, phosphorus, calcium, magnesium, bicarbonate, sodium, and chloride. When only phosphate was added to TD, the Q.EEG slowed to the same level achieved after M-UD. We conclude that uremic encephalopathy in this model is produced by an unknown neurotoxin and augmented by one or more of the M-UD solutes, phosphate being a likely candidate. To localize the encephalopathic effect, regional brain glucose uptake was estimated in 20 discrete brain areas. Significance of reduced uptake in three areas is discussed.

Lipoxin A4 antagonizes cellular and in vivo actions of leukotriene D4 in rat glomerular mesangial cells: evidence for competition at a common receptor.

Lipoxin A4 (LXA4) was competitive with [3H]leukotriene D4 (LTD4) for specific binding to cultured rat glomerular mesangial cells. Half-maximal inhibition was obtained with 100 nM LXA4, compared with 10 nM for unlabeled LTD4. At 10 and 50 nM LXA4 induced low, but significant, increases in mesangial-cell inositol trisphosphate generation: 48% and 44% increases as compared to vehicle controls, respectively (compared with 146% and 106% increments obtained for equimolar LTD4), which were abolished in the presence of 100-fold concentrations of the LTD4 receptor antagonist, SKF 104353. In addition, exposure to 100 nM LXA4 prevented mesangial cell inositol trisphosphate generation induced by 10 nM LTD4. To test the in vivo relevance of these results, we established a dose-response curve for the reducing effects of intrarenal arterial LTD4 on glomerular filtration rate and renal plasma flow in anesthetized rats (LTD4 doses were 0.5, 7.0, 14.0, and 20.0 micrograms/kg per min) without or with LXA4 at 1 microgram/kg per min. Mean percent decreases in glomerular filtration rate/renal plasma flow during LTD4 administration were 27*/24, 25*/40*, 70*/65*, and 73*/70* at the above doses, respectively (*P less than 0.05 versus baseline). With LXA4, these values were as follows: 9/20*, 11/37*, 42*/51*, and 50*/68*, the latter value representing a shift in the LTD4/glomerular filtration rate dose-response curve. Thus, LXA4 competes for [3H]LTD4 binding to mesangial cells, its presence prevents LTD4-induced inositol trisphosphate generation, and its own stimulation of mesangial-cell inositol trisphosphate is blocked by an LTD4 receptor antagonist. In vivo, LXA4 antagonizes LTD4-induced falls in glomerular filtration rate but not renal plasma flow, implying prevention of LTD4-mediated reductions in the glomerular ultrafiltration coefficient, a consequence of mesangial-cell contraction. These results suggest that LTD4 and LXA4 interact at a common site on rat mesangial cells at which LXA4 provokes partial agonist responses and competitively antagonizes both the cellular and physiological actions of LTD4. Moreover, these results provide evidence for a potential counterregulatory interaction between leukotrienes and lipoxins that may be relevant during glomerular inflammation.

Glomerular responses to platelet-activating factor in the rat: role of thromboxane A2.

In view of its role as a pro-inflammatory mediator in glomerular injury, we investigated the renal cortical microcirculatory responses to the intrarenal arterial administration of platelet-activating factor (PAF) in the anesthetized euvolemic Munich-Wistar rat. Close arterial administration of PAF led to dose-dependent reductions in renal plasma flow rate (RPF), glomerular filtration rate (GFR), and filtration fraction (FF), in the absence of hypotension or hemoconcentration. Single-nephron (SN) plasma flow rate (QA), SNGFR and SNFF also fell [126 +/- 7 to 101 +/- 6 nl/min (P less than 0.005), 40.6 +/- 2.1 to 21.5 +/- 2.5 nl/min (P less than 0.005), and 0.33 +/- 0.03 to 0.21 +/- 0.03 (P less than 0.025)]. PAF increased pre- and postglomerular arteriolar resistances [2.32 +/- 0.14 to 2.73 +/- 0.19 (P less than 0.005) and 1.32 +/- 0.13 to 1.45 +/- 0.10(10)dyn.s.cm-5 (P less than 0.05)]. PAF infusion also led to a dramatic reduction in the mean value for the glomerular capillary ultrafiltration coefficient, Kf [0.058 +/- 0.012 to 0.020 +/- 0.003 nl.s-1.mmHg (P less than 0.025)]. PAF-induced changes in renal hemodynamics were abolished in the presence of the cyclooxygenase inhibitors, indomethacin and ibuprofen. When administered concomitantly with a thromboxane A2 (TxA2) receptor antagonist, PAF led to significant increases in RPF and GFR. In isolated glomeruli, PAF stimulated the biosynthesis of TxB2 in a dose-dependent manner. Thus PAF depresses rat glomerular function by inducing contraction of arteriolar and mesangial smooth muscle. These effects are likely mediated via the secondary release of TxA2.