[Hip implant revision. Avoiding mistakes and managing risk]. / Implantatrevisionen am Hüftgelenk. Fehlervermeidung und Risikomanagement.

Hip revision surgery may lead to unexpected complications, with a negative impact on the treatment outcome. To refer to possible difficulties as"mistakes" is less helpful than defining ways to foresee such difficulties and developing possible strategies to avoid them. This approach requires a comprehensive amount of personal experience, which may follow consideration of some basic"rules" and possible surgical scenarios before an intervention. The author presents an individual risk management approach that includes hints on how to foresee the occurrence of certain intraoperative difficulties and how to help avoid errors by incorporating forward-thinking strategies into hip revision surgery.

Retrograde blood flow in the aortic arch determined by transesophageal Doppler ultrasound.

BACKGROUND: Aortic arch atheromas may be important sources of cerebral embolism. Aortic plaques are frequently found somewhat distal to the origin of the cerebral arteries, implying that cerebral embolization from such plaques depends on local retrograde blood flow components in this area. Therefore, we investigated the occurrence of blood flow reversal in this part of the aorta. Furthermore, since the presence and magnitude of retrograde flow might be influenced by aortic wall properties, we also studied the relationship between plaque size and distribution, aortic strain and degree of retrograde flow. METHODS: We evaluated aortic arch ante- and retrograde blood flow velocities in 56 patients by transesophageal echocardiography using color-Doppler-guided pulsed-Doppler techniques. The velocity-time integrals (VTI) were measured and the diastolic/systolic VTI ratio was calculated. RESULTS: Retrograde diastolic blood flow was noted in all subjects, and diastolic/systolic VTI ratios were higher (p < 0.05) in patients with plaque >or=4 mm (n = 17) compared to those (n = 39) without. Patients exhibiting plaques exclusively in the aortic arch showed the highest VTI ratios (p < 0.01) and tended to have the lowest strain values. Aortic strain was also reduced in patients >50 years of age (p < 0.01). CONCLUSIONS: Our findings demonstrate retrograde aortic flow in all subjects and its proportion increases in subjects with atherosclerosis, particularly in the aortic arch. Aortic plaques situated distally to the origin of the cerebral arteries are therefore possible sources of cerebral emboli.

Effect of varicose vein surgery on venous reflux scoring and plethysmographic assessment of venous function.

BACKGROUND: Colour duplex ultrasonography (CDU) is widely recommended before varicose vein surgery, combined with quantification of venous reflux by plethysmography where required. This study assessed venous haemodynamics before and after varicose vein surgery by venous outflow plethysmography (VOP), venous reflux plethysmography (VRP) and by adoption of a modified segmental venous reflux score (VRS). The effect of wearing one or two class I medical compression stockings was also assessed. The aim of the study was to identify parameters which reflect the outcome of treatment using medical compression stockings or surgical intervention. METHODS: 24 legs of 21 patients with superficial vein incompetence of clinical grade C(2-4a) (CEAP) were assessed before and a mean of 8 S.D. 4 months after superficial vein surgery. Investigations were CDU, as well as VOP and VRP using mercury in rubber gauges fitted either around the calf or the forefoot. Venous reflux was semi-quantitatively graded by CDU in relation to the actual vein diameter and transformed into a VRS with respect to the number of involved serial vein segments. The venous reflux rates were measured in standing patients after knee bending before and after application of one or two superimposed compression stockings (class I). RESULTS: According to VRP, one compression stocking reduced the maximum venous reflux rates (VR(max)) by about 30% which was comparable with the effect of surgery on VR(max). Two superimposed compression stockings were almost twice as effective and diminished VR(max) pre- and post operatively by around 60%. Varicose surgery reduced the maximum venous outflow rates significantly (pre-op: 166 S.D. 77 ml/min x 100 ml tissue, post op: 120 S.D. 34) and improved VRS (pre-op median 5.0 IQR: 4.5-5.5, post-op median 0.5 IQR: 0-1.0). Surgery had no effect on venous refilling time or venous reflux rates when measured without compression stockings. CONCLUSION: Venous reflux assessed by plethysmography was moderated by the use of compression stockings pre-operatively but did not reflect the outcome of surgical treatment of superficial venous reflux. Increased venous volume and venous outflow were restored to the levels of normal contralateral limbs by surgery. The VRS decreased considerably following surgery, reflecting the effect of surgical treatment on the number of incompetent venous segments. Changes in this parameter did not correlate with any of the plethysmographic measurements.

[In vitro studies on various PMMA bone cements: a first comparison of new materials for arthroplasty]. / In-vitro-Untersuchung unterschiedlicher PMMA-Knochenzemente--ein erster Vergleich neuer Materialien für die Endoprothetik.

AIM: Two clinically established PMMA bone cements (Refobacin Palacos R and Palacos R + G) and two newer cements not yet in widespread clinical use (Refobacin Bone Cement R and SmartSet GHV) were tested in vitro for practically relevant differences. METHODS: The tests included chemical analyses, handling properties and testing according to the ISO standard for PMMA bone cements. RESULTS: The results obtained indicate clearly that the copolymers used in Refobacin Bone Cement R and SmartSet GHV differ from those used in the Palacos cements. There were also significant differences in viscosity behaviour and waiting time (p < 0.01 for Palacos cements versus Refobacin Bone Cement R) as an expression of different handling properties. The hardening times under ISO 5833 conditions also differed significantly (p < 0.01 and p < 0.05 for Palacos cements compared with Refobacin Bone Cement R and p < 0.01 for Refobacin Bone Cement R compared with SmartSet GHV). CONCLUSION: In view of these differences in material properties, the clinical data from long-term use of the bone cements Refobacin Palacos R and Palacos R + G cannot be extrapolated to the newly developed PMMA cements Refobacin Bone Cement R and Smart GHV. Before broad clinical use of these cements, prospective clinical studies using RSA or DEXA and, as a second step, statistically powerful prospective comparative studies should be performed. Until these data are available, patients in whom Refobacin Bone Cement R and SmartSet GHV are used should be informed that the material employed deviates from the standard procedures for cemented joint replacement in the Scandinavian arthroplasty registers and that the long-term consequences cannot, in the final instance, be foreseen. This is essential in order to avoid later malpractice claims on the grounds of inadequate information.

Prevalence of micro-emboli in symptomatic high grade carotid artery disease: a transcranial Doppler study.

BACKGROUND AND PURPOSE: Echolucent carotid plaques, as well as downstream micro-embolisation, may be associated with an increased risk of stroke. However, the relationship between carotid plaque ultrasound characteristics and micro-embolic signals (MES) detected in the middle cerebral artery (MCA) is still controversial. The purpose of this study was to investigate the prevalence of MES in patients with symptomatic high-grade internal carotid artery (ICA) stenosis and to identify predisposing factors, such as plaque echogenicity and intra stenotic blood flow velocity pattern. METHODS: 197 patients (mean age 69.5+/-8.6, 161 males) with confirmed symptomatic high-grade ICA stenosis and anti-platelet treatment underwent bilateral MES monitoring for 30 minutes within the anterior circulation, using Power M-mode transcranial Doppler techniques (TCD). Carotid artery plaques were characterized by Gray-Weale scaling. RESULTS: In 32.0% of the patients, we detected MES by TCD within the MCA on the symptomatic side, but the same finding was made in only 4.5% on the corresponding asymptomatic site (p<0.0001). The presence or absence of MES was associated with neither ultrasonic plaque characteristics nor the intrastenotic blood flow velocities at peak systole and end diastole. The median time since the last ischemic event symptoms was shorter in the patient group with MES [+] than in MES [-] (p=0.013). CONCLUSIONS: Despite optimum standard anti-platelet therapy, cerebral micro-embolisation occurs in 30% of patients with symptomatic carotid artery disease, which might therefore be a possible risk factor for recurrent neurological symptoms. However, the presence of MES is independent of intrastenotic blood flow disturbances and grey scale ultrasound plaque characteristics. The presence of MES as an indicator of unstable plaque and thereby a possible risk factor for stroke should be evaluated prospectively using various algorithms for plaque classifications.

Treatment of periprosthetic femoral fractures with the Bicontact revision stem.

PURPOSE: Periprosthetic fractures in cases without prior loosening of the stem can be treated with open reduction and internal fixation, but cases with preexisting loosening and/or bone defects present specific challenges to the surgeon. The keys to the success of intramedullary stabilization of femoral fractures--reconstruction of length, axis and rotation rather than meticulous reduction of the fragments and minimal impact on fragment vascularization by the surgical approach--can be transferred to the treatment of periprosthetic fractures. METHOD: The Bicontact revision stem can be regarded as a combination of an interlocking nail in its distal part and a proximally coated femoral stem in its proximal part. The transfemoral approach respects the vascularization of the bone, although it is not minimally invasive. Forty-one patients with a mean age of 72.3 years and a periprosthetic fracture were included in this study. According to the Vancouver classification there were 2 type A fractures of the trochanteric region, 14 were B1, 8 were B2 with prior loosening, 13 were B3 with significant bone loss, and 2 fractures were distal to the tip of the prosthesis (type C). RESULTS: In all patients, intramedullary stabilization with a Bicontact revision stem was performed. All but three fractures healed (pathologic fracture with multiple myeloma in one case, impaired bone healing in two cases). In 7 patients, further procedures had to be undertaken (new periprosthetic fracture in 2, loosening and revision with a standard prosthesis in 2, revision with a long stem prosthesis together with bone grafting in 3 cases). At follow-up, after a mean of 4.3 years, all patients were able to walk, and the mean Harris Hip Score was 71.1 points. CONCLUSION: In conclusion, combined application of the principles of intramedullary nailing and of uncemented total hip replacement by use of the distally interlocked Bicontact revision stem enables successful treatment of periprosthetic femoral fractures.

Treatment of large femoral bone defects--15-year experiences with the cementless Bicontact revision stem with distal interlocking.

AIM: With the steady growth in the number of hip arthroplasty revision operations, the concept and long-term results of the Bicontact revision stem with distal interlocking for the treatment of extensive femoral bone defects were investigated in this prospective study. METHOD: The first 156 stem revision operations performed between January 1992 and December 2002 were evaluated. The indication for operation was aseptic loosening in 133, stem fracture in 14, recurrent dislocation in 2 and reimplantation following Girdlestone removal of a septic prosthesis in 7. The cup component was revised at the same time in 74 cases. RESULTS: Higher-grade femoral bone defects were found intraoperatively in 66 %. The average age of the patients was 71.4 (34 - 88) years at operation and 76.9 (44 - 94) years at the last follow-up. The average period until follow-up, re-revision or loss to follow-up was 5.54 (0.1 - 14.9) years. The clinical and radiological follow-up rate (with reference to the total number of patients) was 35 % (55 von 156), and 51 % (55 of 107) with reference to patients still living. The median Harris Hip Score was 63.7 points. In the observation period, 12 stems were exchanged for a cemented standard stem, 5 stems were removed because of infection and 2 stems were revised because of periprosthetic fracture. The calculated survival rate for the stems after 14.9 years was 85.9 %. CONCLUSION: The 15-year results confirm the biomechanical concept of the Bicontact revision stem with optional distal interlocking for the treatment of extensive bone defects in stem revision surgery.

Revision surgery in high grade acetabular defects with thermodisinfected allografts.

AIM: Due to new medical knowledge and legal restrictions, it is increasingly difficult to run a traditional allogenic bone bank so that alternative bone substitutes and methods of processing are being sought worldwide. METHOD: In a prospective clinical study, the biological efficacy of thermodisinfected and then cryopreserved allogenic bank bone was investigated in 19 acetabular revisions in 18 patients. Simultaneously a newly developed titanium reconstruction ring was used. Any revision was regarded as an end point and the follow-up with radiological and clinical results were recorded. RESULTS: The mean follow-up period was 8.1 (7.9 - 9.8) years. The patients were 73.5 years old (46 - 91) at the time of the revision surgery. One case had a septic course necessitating revision surgery. The other cases showed increasing homogeneity compared to the opposite side and gradual adaptation to the radiological structures found there beforehand. Screw breakage was observed in 3 cases but no implant failure, migration tendency or change in the position of the reconstruction ring or PE-cup. CONCLUSION: Despite the low case numbers and different baseline situations, it can be concluded that thermodisinfected cancellous bone chips enable similarly good acetabular reconstruction as the routinely tried and tested cryoconserved, non-processed bone bank allograft, which is becoming increasingly difficult to obtain because of altered guidelines and legislation. The newly developed reconstruction ring has proven itself because of the improved range of sizes and the possibility of adjustment to the anatomical circumstances together with its outstanding material characteristics in clinical use.

Prospective long-term follow-up of the cementless bicontact hip stem with plasmapore coating.

AIM: A prospective long-term study of the first 250 cementless Bicontact stems implanted in the BG Trauma Centre, Tuebingen, Germany. METHOD: All of the patients in this series (treatment period June 1987 to April 1990) who were still contactable were invited for clinical and radiological follow-up. The radiographs were analysed for signs of loosening in the form of Gruen lysis zones, stress shielding, subsidence behaviour, heterotopic ossification and spot welds. RESULTS: The average follow-up period was 17.8 (16.7 - 19.5) years. The overall rate of follow-up was 65 % (162 of 250) and 91 % of patients who were still alive (162 of 179). The average patient age was 56.2 years at the time of operation and 74.0 years at follow-up. The average HHS was 81.6 points. In the course of the first 10 years (up to 03/1998), a total of 8 stem revisions had to be performed. In the period from 03/1998 to 01/2007, 2 cases of loosening requiring revision occurred in the patients still alive at the time of follow-up. The survival rate calculated was thus 95.6 %. CONCLUSION: These outstanding results provide enduring support for the philosophy of the cementless and bone-preserving fixation principles underlying the Bicontact hip stem with proximal intertrochanteric transmission of forces and high primary rotational stability.

Leg ulcer recurrence and its risk factors: a duplex ultrasound study before and after vein surgery.

OBJECTIVES: Assessment of risk factors for ulcer recurrence in chronic leg ulcer patients treated by varicose vein surgery. DESIGN: Retrospective follow-up study. MATERIALS: 62 patients, 43 women and 19 men (Median=56.5 years, range 24-77) with the CEAP classifications of C(5)-C(6) and E(P) (primary venous insufficiency). METHODS: Patients underwent colour duplex ultrasound (CDU) investigation before varicose vein surgery. Post-operatively CDU, ambulatory venous pressure (AVP) and an interview were performed. The median clinical follow-up was 5.5 years (range 2-11 years). RESULTS: The estimated 5-year ulcer recurrence rate was 19% in all patients. The risk of ulcer recurrence was significantly lower (p<0.05) in legs without residual varices or recurrence. The five year risk of ulcer recurrence depended on the time interval between ulcer appearance and the surgical intervention (index operation), post-operative venous axial reflux and AVP (mmHg). More than 50% of the patients had a calculated probability of ulcer recurrence of less than 3%, but 13% had a probability of more than 23% based on our analysis. CONCLUSIONS: A long history of venous ulcer is a pre- and post-operative risk factor for recurrent ulceration. Total elimination of incompetent superficial and perforator veins lowers the risk of ulcer recurrence, whereas residual axial reflux increases the risk. Postoperative CDU is effective in identifying patients at risk of ulcer recurrence.

Long-term results of an uncemented straight femoral shaft prosthesis.

The first consecutive series of 250 implantations of an uncemented, proximally anchored straight femoral shaft prosthesis in 236 patients is included in this prospective follow-up study. Average time of follow-up evaluation was 11.8 years (range 10.6-13.7 years). At follow-up, 41 patients with 44 hips had died and three could not be located. Eight hips were revised, two for infection, one for recurrent dislocation, two for rapid subsidence due to component undersizing and one for aseptic loosening of a varus-malaligned stem; two radiologically well-fixed stems were revised during acetabular revision. Survival estimate showed an overall survival of 96.6% after 14 years (confidence limits: 98.4% (upper) and 92.8% (lower)). The median Harris hip score at time of follow-up was 81.4 points; clinical results were compromised by high loosening rates (68.8%) of the threaded cup, which had been used in 165 of the 250 cases. Radiologically, tiny reactive lines (<2 mm) were frequently present in the distal zones of the femoral shaft, but could be found in the proximal anchoring zone in only one case. In conclusion, the long-term follow-up results with this femoral component are encouraging and are comparable to those of modern techniques of cementing in primary total hip arthroplasty.

[Good long term results with a cemented straight femoral shaft prosthesis made of titanium]. / Gute langfristige Nachuntersuchungsergebnisse einer zementierten Titan-Geradschaftprothese.

A higher-than-average rate of aseptic loosening has been postulated to be associated with the combination of a titanium stem and bone cement. In this prospective follow-up study we therefore investigated our first consecutive series of 250 implantations of a cemented femoral shaft prosthesis made of titanium alloy (BiCONTACT((R)), Aesculap, Tuttlingen, Germany). Average time of follow-up evaluation was 9.7 years (range 8.7-10.3 years). At follow-up, mean patient age was 81 years; 89 patients with 93 hips have deceased and two could not be located. Follow-up rate was 98.7% for the patients still alive at time of follow-up evaluation. Five patients have been revised, two for infection and one for aseptic loosening of a varus-malaligned stem; two radiologically well-fixed stems had been revised during acetabular revision. Survival estimate showed a calculated cumulative survival rate of 97.5% after 11 years [confidence limits: 99.0% (upper) and 94.1% (lower)]. The average Harris hip score at time of follow-up was 82.25 points.Radiologically, signs of loosening could be detected in 3 stems: in one case varus malalignement deteriorated with time and in 2 cases osteolyses developed together with significant polyethylene wear. All 3 patients experienced only mild pain and revision had not been indicated so far. In conclusion, the long-term follow-up results with this cemented titanium femoral component are encouraging and are comparable to other successful cemented femoral components in primary total hip arthroplasty. No increased risk for aseptical loosening was associated to the combination of titanium and cement in this specific stem. Design parameters seem to play an important role in the development of aseptic loosening in cemented titanium stems.

Changes in middle cerebral artery blood flow after carotid endarterectomy as monitored by transcranial Doppler.

OBJECTIVE: By using transcranial Doppler (TCD) it is possible to measure blood flow velocities within the circle of Willis. In this study, TCD was performed before and after carotid endarterectomy (CEA) with the aim to describe cerebral hemodynamics after normalization of the carotid artery blood flow. METHODS: Thirty CEA patients were consecutively entered into the TCD study, whereas 15 patients were referred for postoperative TCD for various clinical reasons. All 45 patients were investigated by using TCD: first preoperatively, then during the first few days after CEA before discharge from the hospital, and finally 3 to 12 months later. In addition, all patients underwent duplex investigation of the internal carotid artery the day before surgery and 3 months postoperatively. For the analysis, the patients were divided into two groups, one with (S-group), suspected postoperative neurologic complications/symptoms and another one without (C-group). Six patients were assigned to the S-group and 37 to the C-group, the latter including two patients who underwent bilateral CEAs. RESULTS: In the whole study group,a significant postoperative increase in systolic flow velocity was recorded bilaterally in the middle cerebral artery (MCA) as measured some days after surgery. The patients in the S-group showed high blood flow velocities mainly in the MCA on the ipsilateral side. A contralateral flow velocity increase did not occur in patients with very severe contralateral stenosis or occlusion (n = 9) if the late follow-up investigation was chosen as a reference value. Twenty patients in the C-group formed a subgroup with high blood pressure and/or headache postoperatively (CB-group) The other 19 patients were referred to as the CA-group. The CB- and S-groups showed more pronounced vessel disease in internal carotid artery on the contralateral side combined with lower collateral capacity in the circle of Willis compared to the CA-group. In the S-group the mean +/- standard deviation peak systolic velocity in ipsilateral MCA increased from a preoperative value of 0.71 +/- 0.22 m/sec to 2.23 +/- 0.72 m/sec (P <.005). In the CB-group, we observed a bilateral MCA blood flow velocity increase from 0.72 +/- 0.18 to 1.35 +/- 0.56 m/sec (P <.0001) on the ipsilateral side and from 0.82 +/- 0.37 to 1.28 +/- 0.66 m/sec (P < 0.001) on the contralateral side. In the CA-group, we observed minor bilateral blood flow velocity increases in the MCA, from 0.79 +/- 0.25 m/sec to 1.03 +/- 0.33 m/sec on the ipsilateral (P <.001) and from 0.70 +/- 0.17 m/sec to 0.93 +/- 0.26 m/sec on the contralateral side (P <.005). At the follow-up 3 to 12 months after surgery, the MCA flow velocities had returned to normal. CONCLUSIONS: Soon after surgery, blood flow velocity increases often bilaterally in the MCA. However a contralateral flow velocity increase did not occur in patients with very severe contralateral stenosis or occlusion if the late follow-up investigation was chosen as a reference value. The clinical significance of bilateral flow velocity increases is uncertain, but very high blood flow velocities might be a signal for cerebrovascular hyperperfusion. In those patients, increased postoperative surveillance is recommended.

Cerebral atherosclerosis as predictor of stroke and mortality in representative elderly population.

BACKGROUND AND PURPOSE: The aim of this study was to assess the relationship between cardiovascular risk factors, atherosclerotic disease in the carotid bifurcation, and the risk of stroke and mortality in a representative population sample. METHODS: One hundred forty-two men and women participated in a population study at ages 70 and 76 years. At age 78, extracranial and intracranial circulation was examined by means of duplex sonography and transcranial Doppler techniques. Mortality and hospitalization for stroke were analyzed over a 5-year follow-up period up to age 83 years. RESULTS: Carotid plaques were identified in 82% of the men and 79% of the women. Bilateral plaques were found in 57% of the men and 46% of the women, and stenosis resulting in >50% diameter reduction occurred in 28% of the men and 17% of the women. Carotid stenosis >75% was observed in 7 subjects (0.5%). Bilateral plaques at age 78 were correlated with systolic blood pressure and ischemic heart disease at age 70 years. The pulsatility index was 1.0 to 1.4 in 63% and > or =1.5 in 13% of the study population. The pulsatility index was correlated with systolic and diastolic blood pressure, serum cholesterol, and triglycerides. Men with bilateral carotid plaques at age 78 years had an increased risk of stroke or mortality during the 5-year follow-up period (74% bilateral plaques versus 21% unilateral or no plaques). This was not found in the women (33% versus 26%). CONCLUSIONS: Carotid atherosclerosis was prevalent in a majority of elderly subjects. Bilateral plaques were correlated with systolic blood pressure and ischemic heart disease at age 70 years and predicted the risk of stroke and mortality in men but not in women.

Influence of poststenotic collateral pressure on blood flow velocities within high-grade carotid artery stenosis: differences between morphologic and functional measurements.

PURPOSE: The driving force for blood flow through a high-grade stenosis in the internal carotid artery can be expressed as the pressure gradient over the stenosis itself, which, however, might be reduced by the back pressure exerted by distal collateral vessels. Theoretically the maximum blood flow velocity as a measure of the functional grade of obstruction may therefore be lower than what is expected from morphologic gradations of the stenosis. This study was designed to test prospectively the influence of intracranial collateral vessels on blood flow velocities within high-grade internal carotid artery stenoses. PATIENTS AND METHODS: Forty-five consecutive patients (age 66 +/- 11) with high-grade internal carotid artery stenoses were investigated before and during carotid endarterectomy. The preoperative investigations included duplex ultrasound scanning of the neck vessels, transcranial Doppler scanning for assessment of collateral flow to the middle cerebral artery and angiography. Carotid endarterectomy was performed with patients under deep general anesthesia without a shunt. Systolic and diastolic internal carotid artery blood pressures were measured before and during intraoperative cross-clamping (ie, stump pressure) of the carotid arteries. RESULTS: Within high-grade internal carotid artery stenoses, maximum systolic and end-diastolic blood flow velocities showed a significant inverse correlation to the corresponding systolic and diastolic stump blood internal carotid artery blood pressures. All patients with spontaneous collateral flow to the ipsilateral anterior part of the circle of Willis were divided into a group with relatively high and another one with low end-diastolic blood flow velocities. The stump pressure was significantly lower in patients with high end-diastolic blood flow velocities in spite of the fact that the mean angiographic grade of stenosis did not differ significantly between the groups. CONCLUSIONS: Flow velocities within a high-grade internal carotid artery stenosis are inversely dependent on the stump pressure, that is the poststenotic collateral perfusion pressure. This should be taken into consideration in case of discrepancies between angiography and ultrasound outcome.

Results of a cemented titanium alloy straight femoral shaft prosthesis after 10 years of follow-up.

Two-hundred fifty implantations of a cemented femoral stem made of titanium alloy in 239 patients were followed for 9.7 years (range 8.7-10.3 years). Eighty-nine patients with 93 hips have died and two could not be located. Five hips have been revised, two for infection, one for aseptic loosening and two during revision of the cup. Three stems showed radiological loosening but have not been revised. The average hip score was 85. The results are encouraging and comparable to other cemented femoral stems.

Allogeneic cancellous bone graft and a Burch-Schneider ring for acetabular reconstruction in revision hip arthroplasty.

BACKGROUND: There is an ever-increasing number of failed hip arthroplasties associated with massive deficiency of acetabular bone stock consisting of a segmental or cavitary defect. This study was undertaken to evaluate the long-term results after use of morselized cryopreserved allogeneic bone graft and an antiprotrusio cage to treat such a deficiency. METHODS: From January 1, 1988, to January 1, 1994, forty-one patients (forty-one hips) with an acetabular defect classified as type IIl or IV according to the American Academy of Orthopaedic Surgeons system were operated on with use of a Burch-Schneider ring and morselized cryopreserved allogeneic cancellous bone graft. Thirty-eight patients (thirty-eight hips) were available for clinical and radiographic follow-up examinations at an average of 7.3 years (range, 4.2 to 9.4 years) after surgery. RESULTS: All measured clinical parameters had improved significantly by the time of the follow-up examination (p < 0.0001). Radiographs confirmed that none of the thirty-eight hips had any measurable migration or displacement of the acetabular component and that osseous consolidation occurred only within the grafted area in all patients. CONCLUSION: Acetabular reconstruction with use of morselized cryopreserved allogeneic cancellous bone graft and the Burch-Schneider ring can be highly successful in managing massive acetabular deficiencies in revision hip arthroplasty.

Evaluation of posterior cerebral artery blood flow with transcranial Doppler sonography: value and risk of common carotid artery compression.

PURPOSE: Investigations of the posterior cerebral arteries (PCA) by transcranial Doppler sonography (TCD) may be less reliable than investigations of the anterior part of the circle of Willis. Nevertheless, a true PCA may be identified by manual compression of the proximal common carotid artery (CCA) during TCD. Therefore, we used CCA compression in clinically indicated TCD studies and assessed retrospectively its risks and prospectively its benefits for PCA evaluations. METHODS: Using the transtemporal approach, we prospectively assessed flow velocities in posteriorly located blood vessels in 180 consecutive patients before and during CCA compression. The complications of CCA compression were retrospectively reviewed in all 3,383 clinical TCD investigations performed over an 8-year period. RESULTS: Decreased flow velocities during ipsilateral CCA compression occurred in 17% of patients. A PCA-like vessel with perfusion from the carotid artery or PCA supply from the carotid circulation was unmasked. Mixed distal PCA support by the posterior communicating artery and proximal PCA could not be shown by TCD. Transient cerebral symptoms occurred in less than 0.4% of the 3,383 retrospectively reviewed TCD investigations; no other adverse effects were seen. CONCLUSIONS: TCD without CCA compression may lead to false identification of the PCA. Since transient cerebral symptoms during CCA compression are rare, CCA compression can be used when a clinical TCD investigation of intracranial collateral blood flow compensation is indicated or when the identification of a cerebral artery is uncertain.

Evaluation of duplex ultrasound and captopril renography for detection of renovascular hypertension.

BACKGROUND: Renovascular hypertension is the most common form of curable secondary hypertension and, if untreated, may lead to end-stage kidney disease. Given that renal function and hypertension may improve after renal angioplasty, it is pertinent to identify patients with renal artery stenosis. The aim of the present study was to evaluate both duplex ultrasound and captopril renography for detection of renal artery stenosis among hypertensive patients. METHODS: To avoid selection bias, all patients referred to our center for evaluation of renovascular hypertension were asked to participate in the study. Patients were examined by intra-renal duplex ultrasound (N = 121), measuring pulsatility index and acceleration of the blood flow during early systole. In 98 patients, 99mTc-DTPA captopril renography was performed in conjunction with duplex ultrasound. Renal angiography was performed in all patients regardless of the results of the noninvasive tests. RESULTS: The prevalence of renal artery stenosis was 19%. In the 98 patients examined by both duplex ultrasound and captopril renography, sensitivity and positive predictive values for detection of a renal artery stenosis of 50% degree or more were 84 and 76%, respectively, for duplex ultrasound, whereas captopril renography was associated with a sensitivity and positive predictive value of 68% for both (P = NS). Specificity and negative predictive values were 94 and 96%, respectively, for duplex ultrasound, whereas the corresponding values for captopril renography were 92% for both (P = NS). Specificity and negative predictive values were 94 and 96%, respectively, for duplex ultrasound, whereas the corresponding values for captopril renography were 92% for both (P = NS). CONCLUSIONS: Both duplex ultrasound and captopril renography are associated with high specificity and negative predictive values for detection of renal artery stenosis. Sensitivity and positive predictive values are at least as good for duplex ultrasound compared with captopril renography. Given that duplex ultrasound is easier to perform and more cost effective, we propose that it should be the method of first choice when screening for renal artery stenosis in a hypertensive population.

Results of an uncemented straight femoral shaft prosthesis after 9 years of follow-up.

The first consecutive 250 implantations of an uncemented, proximally anchored straight femoral shaft prosthesis (BiCONTACT) in 236 patients are included in this prospective follow-up study. Average time of follow-up evaluation was 8.9 years (range, 7.4-10.7 years). At follow-up, 27 patients had died, and 2 could not be located. Seven patients underwent revision-2 for infection, 1 for recurrent dislocation, 2 for component undersizing with rapid subsidence, and 1 for aseptic loosening of a varus-malaligned stem; 1 radiologically well-fixed stem had been revised during acetabular revision. Overall survival was 97.1% after 11 years (confidence limits, 98.7% [upper] and 93.6% [lower]). The average Harris Hip score at time of follow-up was 84.3 points. Radiologically, tiny reactive lines (<2 mm) were present in the distal zones of the femoral shaft, but no radiolucencies could be found in the proximal anchoring zone. The midterm to long-term follow-up results with the evaluated femoral component are encouraging and are comparable to those of modern techniques of cementing in primary total hip arthroplasty.