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C P Duncan

Publications and source records attributed to C P Duncan.

At least 19 recordsLinked to original sources
PubMed2004

Clinical and radiographic assessment of the young adult with symptomatic hip dysplasia.

Acetabular dysplasia is a major precursor of osteoarthritis of the hip. It is important to identify patients before the development of osteoarthritis, because these patients may be candidates for joint-preserving surgery, such as pelvic osteotomy. Patients with hip dysplasia, and no osteoarthritis, present with unique findings on history and physical examination. On history, patients should be questioned for symptoms unique to dysplasia, such as locking, snapping, and feelings of instability. Physical examination should look for signs of labral disease, by using the impingement test. Patients suspected of having symptomatic dysplasia should have plain radiographs, including an anteroposterior radiograph of the pelvis taken with the patient standing, a false profile view, and an abduction view of the hip. The anteroposterior radiograph of the pelvis and false profile view will help to quantify the degree of the dysplasia. The abduction view is important in determining the patient's eligibility for joint-preserving hip surgery. Computed tomography scanning and magnetic resonance imaging are reserved for patients who are operative candidates. Computed tomography scanning can aid in the planning of complex pelvic osteotomies. Magnetic resonance imaging especially is useful for delineating labral disease. It is this combination of history, physical examination, and radiographic workup that will allow successful treatment of the dysplastic hip before the development of osteoarthritis.

Bone Diseases, Developmental↗
PubMed2004

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.

Arthroplasty, Replacement, Hip↗
PubMed2003

Fixation of trochanteric slide osteotomies: a biomechanical study.

OBJECTIVE: (1) Determine the effect of a compressive force on the stability of trochanteric slide osteotomies repaired with a cable repair system or a suturing technique. (2) Develop an approach to surgical decision making for trochanteric repair. DESIGN: Muscle forces acting on the greater trochanter were experimentally modeled by the application of shear and compressive loads to osteotomized greater trochanters. A repeated measures design was used to compare suture and cable fixation. BACKGROUND: The use of cables and wires for trochanteric repair has been associated with a high incidence of acetabular loosening and trochanteric bursitis. With trochanteric slide osteotomies, the vastus lateralis remains attached to the trochanter, which results in a compressive force being generated across the osteotomy and relatively small shear forces. The use of less rigid fixation techniques for trochanteric repair, such as sutures, may reduce the complications of cables and wires. METHODS: Seven cadaveric femora with trochanteric osteotomies were tested sequentially after repair with a cable system and with a suturing technique. A cyclic shear load of constant amplitude was applied while a compressive load was decreased in a stepwise fashion. Migration and cyclic motion of the trochanter were measured, and the coefficient of friction was also determined. RESULTS: Cyclic motions of the trochanter in both superior and anterior directions were generally less than 0.5 mm and were not significantly different between the cables and sutures at high compressive loads. At low compressive loads, cyclic motion was significantly lower with the cable system. CONCLUSIONS: Compression across the trochanteric slide osteotomy has a significant effect on stability. Cyclic motion of the trochanter is similar for both suture or cable repair of a trochanteric slide with good preservation of soft tissue attachments. RELEVANCE: Based on theoretical and experimental evidence, repair of trochanteric slide osteotomies with a suture technique may be a viable alternative to the use of cables and wires in selected cases.

Arthroplasty, Replacement, Hip↗
PubMed2003

Removal of well-fixed, cementless, acetabular components in revision hip arthroplasty.

Removal of well-fixed, cementless, acetabular components during revision arthroplasty remains a challenging problem. Further damage to host bone may limit options for reconstruction and compromise the long-term result of the revision operation. We report the results of 31 hips with well-fixed, cementless sockets which were removed using a new cup extraction system. In all hips the socket was removed without difficulty and with minimal further bone loss.

Acetabulum↗
PubMed2001

Treatment of hip instability.

Instability after total hip arthroplasty is a major source of patient morbidity, second only to aseptic loosening. Certain patient groups have been identified as having a greater risk of instability, including patients undergoing revision arthroplasty as early or late treatment for proximal femoral fractures.

Arthroplasty, Replacement, Hip↗
PubMed2001

Preoperative planning to prevent instability in total knee arthroplasty.

Several factors can lead to persistent instability after total knee arthroplasty, including bone and soft tissue loss, preexisting ligamentous laxity, and poor operative technique. Achieving stability should not be equated with making the knee extremely tight, without any natural laxity.

Arthroplasty, Replacement, Knee↗
PubMed2001

The expectations of patients undergoing revision hip arthroplasty.

Sixty patients were prospectively assessed using the Western Ontario and McMaster Osteoarthritis Index (WOMAC) scale for osteoarthritis of the hip and the Short Form 36 (SF-36) general health status scale as well as the expectation WOMAC, which asked patients to estimate how they expected to feel 6 months after revision hip arthroplasty. There was a wide range of expectations, but we were unable to find any significant correlation between the patients' preoperative pain and stiffness levels and their expectations for pain and stiffness after revision hip arthroplasty. There was no significant correlation between the SF-36 scores and the patients' expectations. Our findings suggest that the expectations of patients awaiting revision hip arthroplasties are high and are not related closely to the level of preoperative disability.

Adult↗
PubMed2001

Unanticipated variations between expected and delivered pneumatic compression therapy after elective hip surgery: a possible source of variation in reported patient outcomes.

The differences between the pneumatic compression thromboprophylaxis delivered after elective total hip arthroplasties and that was expected were quantified before (49 patients) and after a concerted nursing education program (30 patients) that was designed to ensure maximum compliance and to verify the correct application of the devices. The expected therapy was not delivered to any of the patients monitored. Therapy was delivered only an average of 77.8% of the time during the expected treatment periods. During 99.9% of the expected therapy times, values of key outcomes-related parameters of the therapy delivered to the patients varied by >10% from expected values. These variations were not reduced significantly by medical and nursing education. This variation may be a significant confounding factor in comparatively evaluating thromboembolic disease outcome reports.

Adult↗
PubMed2001

Reliability of acetabular bone defect classification systems in revision total hip arthroplasty.

Three classifications for assessment of acetabular bone loss were evaluated for their reliability. The 3 systems assessed were the system described by Gross, the system described by Paprosky, and the classification of the American Academy of Orthopaedic Surgeons. In this study, we assessed their reliability based on the preoperative radiographs alone. Intraobserver agreement was measured by evaluating the classifications by the 3 innovators, 3 reconstructive orthopaedic surgeons, and 3 residents. Interobserver agreement was assessed among the reconstructive surgeons and the residents. The unweighted kappa statistic was used to establish levels of agreement. The innovators had better intraobserver agreement than the other 2 groups. Their agreement was only in the moderate range, however. For the noninnovators, intraobserver and interobserver agreement generally was poor for all 3 classifications assessed. Our results indicate that these classifications do not provide statistically reliable information for preoperative assessment of acetabular bone stock loss.

Acetabulum↗
PubMed2001

Osteotomies around the hip: radiographic planning and postoperative evaluation.

The management of the dysplastic hip represents a clinical and a technical challenge. There is a great deal of variation in the degree and direction of acetabular dysplasia, and the accurate determination of femoral head coverage is difficult. It is, therefore, important to measure and plan any osteotomy based on each patient's unique acetabular anatomy. A clear understanding of the underlying anatomic abnormalities is vital so that reconstruction can be appropriately planned. This understanding is facilitated by an appreciation of the imaging techniques available and their correct application. The initial imaging of the dysplastic hip is based on plain radiographs. These determine the diagnosis of dysplasia and give a good indication of its severity and of the degree of congruency, instability, and degenerative change. A number of indices have been defined on these radiographs to facilitate surgical planning and to evaluate surgical outcomes. Moreover, plain radiographs or fluoroscopy are usually the only modalities accessible during surgery. More complex imaging is necessary to define any associated lesions and to quantify the acetabular deficiency more accurately. Multiplanar imaging using CT scans and computer reconstructions reduces the need for complex spatial interpretation, facilitates preoperative planning, and allows preoperative simulation. The availability of more powerful computers has extended the use of these techniques to intraoperative surgical navigation. Continued progress and development of imaging techniques will further determine the type and degree of correction required for each hip and will help to stratify dysplastic hips for outcomes assessment. Ultimately, it will help orthopaedic surgeons to evaluate whether the success or failure of osteotomies around the hip are intrinsic to the techniques used or to the primary disease process or are related to the surgeon's failure to create a more normal biomechanical environment for the hip.

Adolescent↗
PubMed2001

Conversion of hip arthrodesis to total hip arthroplasty.

With the predictably good outcome now found with THA, hip arthrodesis has limited indications today. The procedure still has a role in the case of the young, heavy demand male with an isolated arthritic hip condition, and developments such as the Cobra head plate have considerably improved success rates. However, a long-term hip arthrodesis can have profound effects on a patient's daily function and activities of daily living. In addition, gait pattern is considerably affected as well as other joints such as the lower back, ipsilateral knee, and contralateral hip. Many patients with a hip arthrodesis will eventually require a takedown of the fused hip and conversion to a THA. The primary indications include fusion in malposition, pseudarthrosis, or severe pain in other joints. The surgeon undertaking such a task must be familiar with the arthrodesis techniques that have been used in the past as well as the equipment that may be required to extract the fixation hardware. Clinical assessment with particular attention to leg-length discrepancy, position of the arthrodesis, and function of the abductors is of paramount importance. The surgeon must carefully review preoperative radiographs to plan the procedure. The surgeon must also be aware of the presence of pathology in other joints. After takedown of a hip arthrodesis and conversion to a THA, patients cannot expect the result to equal the success rates of primary THA. Patients generally can expect an improvement in function and mobility. Back pain and ipsilateral knee pain are usually improved postoperatively, but the effect on contralateral hip pain is less predictable. Many patients will continue to show a positive Trendelenburg sign, but further improvement in strength of the hip abductors can be expected with time. Leg-length discrepancy is generally improved substantially after THA. However, a substantial number of patients will require a walking aid postoperatively. Overall, the risk of complications and the rates of revision after converting an arthrodesed hip to a THA are quite high. The procedure can be complex. Consideration should be given to referring these patients to a specialized center under the care of an experienced arthroplasty surgeon if preoperative planning suggests that the conversion will not be straightforward.

Adult↗
PubMed2000

The reliability and validity of the Vancouver classification of femoral fractures after hip replacement.

This study assessed the reliability and validity of a new classification system for fractures of the femur after hip arthroplasty. Forty radiographs were evaluated by 6 observers, 3 experts and 3 nonexperts. Each observer read the radiographs on 2 separate occasions and classified each case as to its type (A, B, C) and subtype (B1, B2, B3). Reliability was assessed by looking at the intraobserver and interobserver agreement using the kappa statistic. Validity was assessed within the B group by looking at the agreement between the radiographic classification and the intraoperative findings. Our findings suggest that this classification system is reliable and valid. Intraobserver agreement was consistent across observers, ranging from 0.73 to 0.83. There was a negligible difference between experts and nonexperts. Interobserver agreement was 0.61 for the first reading and 0.64 for the second reading by kappa analysis, indicating substantial agreement between observers. Validity analysis revealed an observed agreement kappa value of 0.78, indicating substantial agreement. This study has shown that this classification is reliable and valid.

Arthroplasty, Replacement, Hip↗
PubMed2000

Circumferential allograft replacement of the proximal femur. A critical analysis.

The use of proximal femoral structural allografts in revision hip arthroplasty remains controversial. The current study constitutes the mean 8.8 years followup (range, 3-12.5 years) of a consecutive series of 55 proximal femoral allografts in 51 patients. In 46 patients the implant was cemented into the allograft and the distal femur, and the host proximal femur was resected at the time of reconstruction in all but seven patients. Five patients underwent revision surgery for acetabular failure, and six additional patients underwent revision surgery for failure of the proximal femoral allograft. Three patients underwent successful revision surgery and had additional proximal femoral allografts. Failure was caused by graft fracture in one patient, by deep infection in two patients, and by junctional nonunion in three patients. Junctional nonunion was seen in five patients (9%), two of whom were treated successfully with bone grafting and bone grafting and plating, respectively. Instability was observed in six patients (11%). Trochanteric nonunion was seen in 22 patients (43%) and trochanteric escape was seen in 14 patients (27%). The mean Harris hip score improved from 39 to 79 points. Resorption involving the full thickness of the allograft in at least one zone was seen in seven patients. This progressed rapidly and silently within the first 3 years but has yet to lead to the failure of any of the reconstructions. Infection was ruled out in every case. Allograft resorption was seen in seven patients and may be related to a combination of factors. It is most likely that this is an immunologic problem of slow rejection, but it is possible that the distal cement fixation led to stress shielding and resorption attributable to mechanical disuse. The possible protective role of retaining the bivalved host bone as a vascularized onlay autograft remains to be clarified. Although these results justify the continued use of structural allografts for selected patients, continued followup is warranted.

Adult↗