Computer assisted measurement of cup placement in total hip replacement

The introduction of image guided systems in total hip replacement surgery provides the ability to plan precisely the alignment of the acetabular cup before surgery, and to perform the surgery according to the preoperative plan. Preoperative planners (interactive computer programs for surgical planning) based on three-dimensional medical images allow planning of optimal placement of implant components based on simulated implant performance. Exact measurement of the cup position during surgery allows precise placement of the cup and accurate measurement of the final position of the cup relative to the pelvis. This measurement is used to evaluate the radiographic techniques for postoperative measurement of cup alignment. Malposition of the acetabular component increases the occurrence of impingement, reduces the safe range of motion, and increases the risk of dislocation and wear. Dislocation of the implant after total hip replacement remains a significant clinical problem. Not fully understanding the interaction between pelvic orientation and final acetabular cup alignment may be one of the main contributing factors in the continued significant incidence of dislocations after total hip replacement. In this study an attempt was made to link the preoperative planning, intraoperative placement, and postoperative measurement of cup placement in total hip replacement using computer assisted techniques.     

Cemented femoral component surface finish mechanics

A cemented femoral component's surface finish may influence implant function through variations in cement adhesion and abrasion properties. Morphologic characterization of historic and current femoral hip prosthesis surface finishes show greater than x 20 range in implant roughness. Early implants typically had relatively smooth surfaces, whereas many of the more recent implants have rougher surface finishes. Smoother implant surfaces have lower cement-metal interface fixation strength, whereas rougher surfaces have greater fixation strength. With interface motion, the smoother surfaces are less abrasive of bone cement, whereas rougher implant surfaces are more abrasive. Because of enhanced bone cement attachment, rougher implant surfaces may have a lower probability of interface motion, while at the same time, a higher debris generation consequence if motion occurs. In contrast, smoother implant surfaces may have a higher probability of interface motion with a lower debris generating consequence of that motion. The prolonged use of cemented total hip replacement may be approached by either extending the duration of implant function after cement-metal interface loosening with smooth surfaced implants or, in contrast, by extending the duration of cement-metal interface adhesion with rougher surfaced implants.     

Arterial vascular lesions after total hip joint replacement

We report on three arterial thromboses of the external iliac artery following total hip replacement. As a result of implanted cement/spongiosa or protrusion of the acetabular component, the iliac vessels were compressed. Furthermore, we report about one intraoperative arterial vessel lesion in a 65-year-old patient during a revision operation. We recommend that in case of acute ischemic syndromes of lower limbs following total hip replacement, an angiography should be performed in order to exclude an extravascular cause of thrombosis. For therapy in those cases extra-anatomic bypasses should be preferred to thrombectomies.     

Computer assisted orthopaedic surgery with image based individual templates

Recent developments in computer assisted surgery offer promising solutions for the translation of the high accuracy of the preoperative imaging and planning into precise intraoperative surgery. Broad clinical application is hindered by high costs, additional time during intervention, problems of intraoperative man and machine interaction, and the spatially constrained arrangement of additional equipment within the operating theater. An alternative technique for computerized tomographic image based preoperative three-dimensional planning and precise surgery on bone structures using individual templates has been developed. For the preoperative customization of these mechanical tool guides, a desktop computer controlled milling device is used as a three-dimensional printer to mold the shape of small reference areas of the bone surface automatically into the body of the template. Thus, the planned position and orientation of the tool guide in spatial relation to bone is stored in a structural way and can be reproduced intraoperatively by adjusting the position of the customized contact faces of the template until the location of exact fit to the bone is found. No additional computerized equipment or time is needed during surgery. The feasibility of this approach has been shown in spine, hip, and knee surgery, and it has been applied clinically for pelvic repositioning osteotomies in acetabular dysplasia therapy.     

Isolation and cytotoxic evaluation of marine sponge-derived norterpene peroxides

Anatomic placement of the acetabular component should be the surgeon's goal at the time of revision THA. However, Acetabular loosening with subsequent implant migration, progressive superior acetabular bone destruction or severe pelvic osteolysis, may prevent the surgeon from obtaining adequate host bone-implant contact needed for a successful reconstruction while maintaining a normal hip center. The high hip center offers a technique for reconstruction of an acetabulum with severe bony deficiency and where the majority of the remaining host bone is superior to the anatomic hip centre.     

Cat-scratch disease presenting as an epitrochlear arm mass

Delayed sciatic neuropathy due to pelvic reconstruction plate loosening following complex acetabular reconstruction in total hip arthroplasty seems not be have been previously reported. We identified a 79-year-old woman who developed progressive neurologic signs of entrapment 6 months following reconstruction of a pelvic discontinuity due to fracture nonunion caused by radiation necrosis. Magnetic resonance imaging of the lumbar spine was unrevealing and electromyography demonstrated a peripheral neurogenic process involving the sciatic nerve. Sciatic nerve exploration was done at 12 months after surgery finding a loose screw in the pelvic plate impinging the nerve. Substantial improvement in clinical symptoms resulted from removal and nerve release.     

Extensile triradiate approach for complex acetabular reconstruction in total hip arthroplasty

The triradiate approach as described by Mears has been used for open reduction of complex dual-column acetabular fractures. Mears extended the anterior limb of this incision to the symphysis pubis by the ilioinguinal approach. From a consecutive series of 43 total hip revisions, this approach was used successfully in seven cases in which extensile exposure was necessary to revise complicated acetabular reconstructions for arthroplasty. The approach was used also to perform complex acetabular reconstruction after en bloc tumor resection. Three patients had severe intrapelvic component protrusio and anterior column deficiency where close proximity of the prosthesis and femoral neurovascular bundle were detected before surgery. Massive allograft and pelvic reconstructions were used to span large anterior column defects and to stabilize pelvic dehiscence. Complications included one hip dislocation and one posterior flap tip necrosis. Follow-up ranged from six to 34 months. No graft failure has been noted.     

Intra and interindividual variations of pelvic mobility in normal adult walk

PURPOSE OF THE STUDY: Pelvis motion appears as a main human gait component, it is linked to the lower limb joints and to the spine. Current devices, especially the opto-electronical systems, allow quantitative and tri-dimensional gait studies. The purpose of this study was to quantify the pelvic motion individual variability in a sample of healthy subjects. MATERIALS AND METHODS: The study based on a 18 volunters sample. There were 14 men and 4 women, ranged in age from 25 to 37 years. A clinical examination and a AP radiograph of pelvis allowed to include healthy subjects. We used the three-dimensional analysis VICON system with five cameras. Nine records were performed for each subject during a free-speed walking. These nine records were distributed on three different days. RESULTS: The step length medianes varied from 1100 to 1600 mm with a significantly (p < 0.05) regression between the step length, the walking speed and the subjects height. Vertical pelvic oscillations varied in this sample from 25 to 60 mm and linked with step length and walking speed. Pelvic rotation around the vertical axis varied from 1.5 to 15 degrees. We did not found regression between this pelvic rotation and the length step. It seems there are three types of pelvic rotation around the vertical axis. At the beginning of the stance phase, in type I, the pelvis is in the transversal plane whereas in the type II, it appears with the maximal rotation. In type III, the value of pelvic rotation is very low. The successive lateral inclinations of pelvic described a complex motion which varied from 1.5 to 9 degrees. The rotation of shoulders around the vertical axis varied from 4 degrees to 13 degrees and the successive inclinations varied from 3.25 degrees to 12 degrees. We did not found any regression between the pelvic and shoulders motion values. DISCUSSION: This study showed that the pelvis motion varied considerably from one subject to another. These variations induce different ways of walking with various consequences on the hip joint and the spine. We suppose that these variations could take a part in etiology of some diseases as hip arthritis or in total hip arthroplasty failure, especially in cup wearing.     

Smoking behaviour and attitudes among adult Saudi nationals in Riyadh City, Saudi Arabia

Nine massive hemipelvic allografts were used to reconstruct the pelvic ring and the hip articulation after resection of malignant tumors. At follow up of 3 to 10 years, six patients were free of oncologic disease. In the 3 acetabular massive allografts, functional results were close from those standard THR. After resection of hemipelvis and adjacent muscles, patients resume a normal family life (painless hip, poor active motion, walking with a crutch) with a functional result much better than after amputation. Considering these encouraging results in oncologic surgery, we used similar technics for reconstruction of very severe bone loss after iterative failures of THR revisions: some examples are reported at medium follow up.     

How outcome studies have changed total hip arthroplasty practices in Sweden

The Swedish Hip Registry has defined the epidemiology of total hip replacement in Sweden. Most hip implants are fully cemented. Serious complications and rates of revision associated with total hip replacement have declined significantly despite an increasing number of patients at risk. During the past 5 years only 9% to 10% of hip replacement procedures are revision procedures. Aseptic loosening with or without osteolysis is the major problem and constitutes 73% of the revisions, but the incidence has decreased four times during the past 15 years to less than 3% at 10 years. Even septic complications can be prevented effectively. Demographics are important because male gender and young age increase the risk for revision because of aseptic loosening. Young female patients with rheumatoid arthritis and male patients with a previous hip fracture have five times higher revision rates than elderly patients. The quality of the surgical technique is the most important factor for reducing the risk for revision because of aseptic loosening, but choice of implant is also important. The variations among hospitals in type of surgical technique used is big enough to cause a 100% difference in revision rate for aseptic loosening. Total hip replacement practice in Sweden has improved based on information from this Registry about individualized patient risks, implant safety, and the efficacy of improving surgical and cementing techniques.     

Gothenburg osseointegrated hip arthroplasty. Experience with a novel type of hip design

The culmination of more than 10 years of laboratory and clinical research has been the clinical trial of a novel hip arthroplasty for osseointegration. The femoral component of this Gothenburg hip is a neck retaining, threaded fixture with rotational symmetry, produced in commercially pure titanium with a specific surface texture. Proximally, a standard orthopaedic taper trunnion mates with a 28-mm diameter zirconia head that articulates against the acetabular component. The latter is also of textured commercially pure titanium, encapsulating a thick ultra high molecular weight polyethylene liner. Dedicated alignment guides and cutting instruments ensure accurate bone preparation and implant placement. Limited clinical trials commenced in 1992 and expanded to multicenter clinical trials in 1997. Every hip has been monitored with radiostereometry to measure migration to an accuracy of 0.1 mm. All calcar implanted femoral components show excellent function at 4 to 5 years followup, with no migration revealed by radiostereometry.     

Assessing colposcopic skills: the instructor''s handbook

As part of the National Study of Primary Hip Replacement Outcome, 402 consultant orthopaedic surgeons from three regions were contacted by postal questionnaire which covered all aspects of total hip replacement (THR). There was a 70% response rate of which 71 did not perform hip surgery, a further 33 refused to take part, leaving 181 valid responses. Preoperative assessment clinics were used by 89% of surgeons, but anaesthetists and rehabilitation services were rarely involved at this stage. Of respondents, 99% used routine thromboprophylaxis, with 79% using a combination of mechanical and chemical methods. Of surgeons, 84% routinely used stockings, whereas 95.5% used chemical prophylaxis, 63% employed low molecular weight heparins. Theatre facilities were shared with other surgical specialties by 6% of surgeons and 18% regularly used body exhaust suits for THR. Antibiotic loaded cement was used by 69% of surgeons, the majority (65%) used a single brand of normal viscosity cement with 9% using reduced viscosity formulations. Modern cementing techniques were commonly used at least in part, 87% used a cement gun and 94% a cement restrictor for femoral cementing. On the acetabulum, 47% pressurised the cement. In all, 36 different femoral stems and 35 acetabular cups were in routine use, but the majority of surgeons (55%) used Charnley type prostheses. Of the surgeons, 57% performed only cemented THR, while 3% exclusively used uncemented THR. Of consultants, 21% followed up their patients to 5 years, the majority discharge patients within the first year. Of concern is a large proportion of surgeons using low molecular weight heparins despite a lack of evidence with regard to reducing fatal pulmonary embolism, and also the small number of surgeons using prostheses of unproven value. Third generation cementing techniques have yet to be fully adopted. The introduction of a national hip register could help to resolve some of these issues.     

Agonist action at D2(long) dopamine receptors: ligand binding and functional assays

Clinical pathways are being introduced by hospitals to reduce costs and control unnecessary variation in care. We studied 766 inpatients to measure the impact of a perioperative clinical pathway for patients undergoing knee replacement surgery on hospital costs. One hundred twenty patients underwent knee replacement surgery before the development of a perioperative clinical pathway, and 63 patients underwent knee replacement surgery after pathway implementation. As control groups, we contemporaneously studied 332 patients undergoing radical prostatectomy (no clinical pathway in place for these patients) and 251 patients undergoing hip replacement surgery without a clinical pathway (no clinical pathway and same surgeons as patients having knee replacement surgery). Total hospitalization costs (not charges), excluding professional fees, were computed for all patients. Mean (+/-SD) hospital costs for knee replacement surgery decreased from $21,709 +/- $5985 to $17,618 +/- $3152 after implementation of the clinical pathway. The percent decrease in hospitalization costs was 1.56-fold greater (95% confidence interval 1.02-2.28) in the knee replacement patients than in the radical prostatectomy patients and 2.02-fold greater (95% confidence interval 1.13-5.22) than in the hip replacement patients. If patient outcomes (e.g., patient satisfaction) remain constant with clinical pathways, clinical pathways may be a useful tool for incremental improvements in the cost of perioperative care. Implications: Doctors and nurses can proactively organize and record the elements of hospital care results in a clinical pathway, also known as "care pathways" or "critical pathways." We found that implementing a clinical pathway for patients undergoing knee replacement surgery reduced the hospitalization costs of this surgery.     

Isolated revision acetabuloplasty using a porous-coated cementless acetabular component without removal of a well-fixed femoral component. A 3- to 9-year follow-up study

The results of isolated acetabular revision performed in 31 patients (32 hips) were monitored for between 3 and 9 years. All femoral components were well fixed and not removed or revised at the time of index surgery. There were 4 hips with little or no acetabular bony defect, 2 hips with pure segmental defects (type I), 10 hips with cavitary defects (type II), 15 with combined segmental cavitary defects (type III), and I with pelvic discontinuity (type IV). All revision acetabular implants were cementless, using a porous-coated hemispheric cup with or without bone-graft. There were four grade I reconstructions, 16 grade II reconstructions, and 12 grade III reconstructions. At final follow-up evaluation 94% of the cups were judged to be stable. Two hips required a second revision acetabuloplasty because of loss of fixation of the cup. The 2 repeat revisions were also done without removal of the femoral component. One acetabular component had evidence of rotational migration, which stabilized and remained nonprogressive. There were no cases of femoral component radiographic or clinical failure. The mean pre and postoperative hip scores were 44 and 83, respectively. The pre- and postoperative pain scores were 12 and 42, respectively. The findings of this study suggest that isolated acetabular revision, using a cementless porous-coated hemispheric cup, can be successfully performed without removing or revising a well-fixed femoral stem and not compromise the final outcome.     

The value of preoperative planning for total hip arthroplasty

To analyse the value and accuracy of preoperative planning for total hip replacement (THR) we digitised electronically and compared the hand-sketched preoperative plans with the pre- and postoperative radiographs of 100 consecutive primary THRs. The correct type of prosthesis was planned in 98%; the agreement between planned and actually used components was 92% on the femoral side and 90% on the acetabular side. The mean (+/- SD) absolute difference between the planned and actual position of the centre of rotation of the hip was 2.5 +/- 1.1 mm vertically and 4.4 +/- 2.1 mm horizontally. On average, the inclination of the acetabular component differed by 7 +/- 2 degrees and anteversion by 9 +/- 3 degrees from the preoperative plans. The mean postoperative leg-length difference was 0.3 +/- 0.1 cm clinically and 0.2 +/- 0.1 cm radiologically. More than 80% of intraoperative difficulties were anticipated. Preoperative planning is of significant value for the successful performance of THR.     

Reoperations of total hip prosthesis with acetabular reconstruction using bone allografts]

Detachment of the acetabular segment is the most important long-term problem with total hip prostheses. We analyzed long-term outcome in our first 48 acetabular reconstructions with cryopreserved allografts. Among the 48 hips operated on with this technique, 38 were reassessed after a mean follow-up of 7 years 3 months (range 5 years-9 years 6 months). Mean age of the population at surgery was 63 years. There were two predominant etiologies: sequelae of chronic hip luxation and primary osteoarthrosis of the hip. In 10 cases with massive destruction, the Müller ring was used to stabilize the allograft. Results were assessed at 6 months, 2 years, 4 years and at longest follow-up using the Merle d'Aubigné clinical assessment scale. For the radiographic assessment, the Ranawat criteria were used to evaluate the alignment of the reconstruction. Clinically, patient comfort was improved in all cases with significant pain relief. Radiologically, mean acetabular ascention was 5 mm and mean medialization was 3.5 mm. A rim was observed in 24 cases including 19 measuring less than 2 cm. Acetabular loosening was evidenced in the 5 other cases where the rim measured more than 2 mm. In 4 of these 5 cases, the acetabulum had migrated to a new setting. The radiographic image then remained unchanged. Analysis of our 38 first cases showed that bone allografts with cimented acetabulum, sometimes with a stabilizing ring, is one of the possible solutions for difficult acetabular reconstructions. However, after a 7 years 3 months follow-up, we have had five (13%) aseptic displacements including one case requiring reoperation. In the 33 stable joints (87%) with good results reconstruction has achieved a nearly perfect anatomic position, similar to first intention arthroplasty with the use of perfectly stabilized bone grafts with a maximal acetabular surface. Our follow-up is longer than most published in the literature. However, the migration rate of 13% it is still too short to draw any conclusion concerning the long-term outcome in our patients, despite their older age and reduced physical activity compared with primary hip arthroplasty patients.     

The fate of pelvic osteolysis after reoperation. No recurrence with lesional treatment

Twenty-three hips (21 patients) with 30 pelvic osteolytic lesions underwent reoperation and were observed prospectively for 25 to 74 months (average, 40 months) to assess the fate of pelvic osteolysis after reoperation. The average radiographic dimensions of the lytic lesions were 2.4 x 1.9 cm with the largest lesion measuring 7 x 5 cm. The porous ingrowth acetabular component shell had been left in situ in 15 hips and had been revised in eight. There was no difference in the average lesional size for hips with revised shells compared with those with unrevised shells. In cases where the shell was left in situ, the osteolytic lesions were curetted by working around the component perimeter or through holes in the shell. In 18 hips the bone defect(s) were grafted with autograft or allograft. Regardless of the management of the acetabular shell or the absence or presence of bone graft, none of the osteolytic lesions have progressed. Twenty-six of the 30 lesions have increased radiographic density. All acetabular components remain radiographically well fixed. There were no new osteolytic lesions. All hips were functioning well, and none have required subsequent reoperation for any reason. There was a statistically significant reduction in the operative time and the amount of blood loss when the acetabular component was not revised. It does not appear necessary to remove a well fixed and well positioned cementless acetabular component for the treatment of pelvic osteolysis. Debridement of periarticular inflammatory tissue and lesional curettage, either with or without bone graft, is effective in managing this type of bone loss. Revision of the acetabular component shell was associated with a significant increase in operative time and blood loss. These results support routine radiographic evaluation after total hip arthroplasty to monitor the development of osteolysis. On the basis of this experience, the authors recommend lesional treatment of progressive pelvic osteolysis to avoid more difficult surgery and minimize patient morbidity.     

Use of osteonics UHR hemiarthroplasty for fractures of the femoral neck

A clinical and radiographic study of bipolar hip arthroplasties was performed for fractures of the femoral neck. All patients were treated with the Osteonics UHR system. Clinical results were evaluated in 77 patients (77 hips) who were observed for an average of 4.8 years (range, 2-10 years). At the latest followup, 67 (87%) patients were rated as having a good or excellent outcome according to the Hospital for Special Surgery hip rating system. Clinical ratings in patients treated with cementless UHR were similar to or better than those of patients with cemented UHR. Hip dislocation occurred in only 3 (2.3%) patients, in whom the hip joint was reduced by a closed procedure without inducing disassembly of the prosthetic components. None of the patients had definitive acetabular erosion. The motion of the outer head was evaluated radiographically in 63 patients in weightbearing and non-weightbearing conditions, 3 to 108 months after surgery. The relative motion at the 2 sites of articulation of the outer head had stabilized by 3 months after surgery and subsequently remained unchanged. The authors' findings indicate that UHR hemiarthroplasty of the femoral head is a reliable treatment for fractures of the femoral neck.     

The Donauspital-Stolzalpe concept (Danube Hospital, Vienna, Austria). Corrective osteotomy with selective labrum surgery following preoperative MRI arthrography

Concomitant pathologies (labral lesions, intra-/extra-osseous ganglia and stress bone marrow edema) in adult residual hip dysplasia (RHD) might influence the outcome of conservative hip surgery. The aim of our prospective clinical study was to assess the value of preoperative MR arthrography in diagnosing concomitant lesions and in making surgical decisions in RHD. The first 37 consecutive patients with a minimum follow-up of 18 months have been analysed. All 37 patients presented RHD with the clinical symptomatology of labral lesions and underwent routine preoperative MRA. According to clinical, radiological and MR arthrographical criteria, these 37 patients were subdivided into four therapeutic subgroups: (1) reorientation of the acetabulum using the T?nnis triple pelvic osteotomy (TPO); (2) intertrochanteric varisation osteotomy (IVO); (3) palliative decompression with only symptomatic partial resection of the torn labrum (PALL); (4) primary total hip replacement (TEP). Based on the preliminary clinical and radiological outcomes of these four subgroups, the following conclusions can be drawn: labral lesions are considered to be a sign of chronic joint instability. Therefore, acetabular malorientation should be corrected by redirectional osteotomy of the acetabulum (TPO-subgroup) even in low grades of RHD if labral lesions are present. "Palliative" labral resections without corrective osteotomy (PALL subgroup) in secondary osteoarthritis due to RHD are definitively obsolete, because they rapidly progress to severe osteoarthritis due to surgically accelerated joint instability. In RHD with highly osteoarthritic hip joints and concomitant lesions, one should not hesitate to perform primary THR even in young patients.     

Significance of arterial circulation disorders for the planning of hip prosthesis interventions

Between 1980 and 1990 a total of 17 patients who had undergone or had been selected for total hip replacement were treated in the Department of Surgery at Münster University. Angiographic studies performed because of persistent symptoms revealed circulatory disorders of the pelvic floor. Vascular surgery was necessary to eliminate symptoms in these patients. Postoperative complications in 3 patients following total hip replacement were also only eliminated by vascular surgery. In the present authors' view, failure to recognize preoperatively existing arterial circulation disorders can lead to misdiagnosis and severe postoperative complications. Every hip replacement operation should be preceded by a thorough clinical and--if doubt persists--an angiological examination. Documented arterial circulation disorders should be eliminated by vascular surgery prior to hip surgery.