The Relationship Between Canal Diameter and the Dorr Classification.

BACKGROUND: Particularly in broach-only uncemented total hip arthroplasty, a narrow femoral canal presents a technical challenge. Traditionally such femurs have been considered to be Dorr A. To our knowledge, however, no study has reported on the relationship between isthmus width and the Dorr classification. METHODS: We reviewed 500 high-quality, hard copy radiographs. Dorr classification and isthmus canal width were measured using an electronic caliper by 5 independent observers with intraobserver and interobserver error calculated. For this study, we defined a narrow canal as being ≤10 mm at its narrowest point (isthmus). RESULTS: Eight percent (40) were Dorr A, 85% (424) Dorr B, and 7% (36) Dorr C. With respect to isthmus width for Dorr A, 63% (25) were ≤10 mm compared to just 13% (55) of Dorr B. However, overall because there were more Dorr B femurs, 69% of those with an isthmus of ≤10 mm were Dorr B. CONCLUSION: In this population, almost 70% of patients with an isthmus ≤10 mm were Dorr B, with only 30% being Dorr A. When using a broach-only technique, isthmus width should be routinely measured on the preoperative anteroposterior radiographs so as to alert the surgeon to potential problems.

A systematic approach to the hip-spine relationship and its applications to total hip arthroplasty.

There remains confusion in the literature with regard to the spinopelvic relationship, and its contribution to ideal acetabular component position. Critical assessment of the literature has been limited by use of conflicting terminology and definitions of new concepts that further confuse the topic. In 2017, the concept of a Hip-Spine Workgroup was created with the first meeting held at the American Academy of Orthopedic Surgeons Annual Meeting in 2018. The goal of this workgroup was to first help standardize terminology across the literature so that as a topic, multiple groups could produce literature that is immediately understandable and applicable. This consensus review from the Hip-Spine Workgroup aims to simplify the spinopelvic relationship, offer hip surgeons a concise summary of available literature, and select common terminology approved by both hip surgeons and spine surgeons for future research. Cite this article: Bone Joint J 2019;101-B:808-816.

Simulation of extreme loads on the proximal femur for implant fixation assessment.

Total joint replacement patients today are younger, heavier, and more active than total joint replacement patients 40 yrs ago. Consequently, patient expectations and prosthesis requirements have increased and there is a need to re-evaluate preclinical testing methods. We present the design rationale for a novel load simulator for the proximal femur, capable of applying a more aggressive load profile than previous simulators. This simulator was used to measure three-dimensional micromotion of a cemented total hip replacement femoral stem under simulated physiological loading. We assessed the influence of a separate abductor muscle force, a higher joint reaction force, and a more accurate implant stability measurement system included in the new simulator and compared the results to the lower, single joint reaction force included in a previously published simulator. Per-cycle motion at both cement interfaces and stem and cement mantle migration obtained from both simulators using the same femoral stem design, are compared. Although the new simulator applied higher loads, per-cycle motions were lower than previously reported. In both studies, regardless of the presence or lack of a separate muscle force, the greatest motions were in the medial-lateral direction (new: 27 +/- 4 mum, old: 67 +/- 21 mum). The findings indicate that magnitude and direction of peak joint reaction force and inclusion of a separate muscle force have a significant effect on femoral stem stability measurements. We recommend that future femoral stem stability studies consider using load simulation techniques and a direct motion measurement system comparable to the one presented in this study.

Spinopelvic mobility and acetabular component position for total hip arthroplasty.

AIMS: Posterior tilt of the pelvis with sitting provides biological acetabular opening. Our goal was to study the post-operative interaction of skeletal mobility and sagittal acetabular component position. MATERIALS AND METHODS: This was a radiographic study of 160 hips (151 patients) who prospectively had lateral spinopelvic hip radiographs for skeletal and implant measurements. Intra-operative acetabular component position was determined according to the pre-operative spinal mobility. Sagittal implant measurements of ante-inclination and sacral acetabular angle were used as surrogate measurements for the risk of impingement, and intra-operative acetabular component angles were compared with these. RESULTS: Post-operatively, ante-inclination and sacral acetabular angles were within normal range in 133 hips (83.1%). A total of seven hips (4.4%) had pathological imbalance and were biologically or surgically fused hips. In all, 23 of 24 hips had pre-operative dangerous spinal imbalance corrected. CONCLUSIONS: In all, 145 of 160 hips (90%) were considered safe from impingement. Patients with highest risk are those with biological or surgical spinal fusion; patients with dangerous spinal imbalance can be safe with correct acetabular component position. The clinical relevance of the study is that it correlates acetabular component position to spinal pelvic mobility which provides guidelines for total hip arthroplasty. Cite this article: Bone Joint J 2017;99-B(1 Supple A):37-45.

Pulmonary emboli followed total hip arthroplasty: incidence study.

We compared twenty-five total hip-arthroplasty patients with twenty-five patients who underwent other operations on the lower extremity, with regard to evidence of pulmonary embolism as determined preoperatively and postoperatively from lung perfusion scans, ventilation scans, and pulmonary angiography. Blood gases and serum enzymes also were studied. The over-all incidence of pulmonary embolism was 6 per cent, despite the absence of clinical evidence of that complication. Abnormalities in scans and blood studies were common preoperatively, so that the diagnosis often depended on the detection of additional abnormalities postoperatively.

Comparison of preoperative radiographs and intraoperative findings of fixation of hemispheric porous-coated sockets.

BACKGROUND: The radiographic criteria for identification of loose cementless acetabular components have not been well established. The purpose of this study was to compare the radiographic appearance of a hemispheric porous-coated cementless cup fixed with screws with the intraoperative findings with regard to the fixation status. METHODS: The quality of the cup fixation was evaluated at fifty-two hip revisions that were performed, for reasons other than infection, at an average of 89.9 months (range, 33.8 to 150.1 months) after the primary operations. The fixation status at the revision surgery was compared with the findings on sequential anteroposterior and lateral radiographs of these sockets. Sequential radiographs of an additional 100 total hip replacements that had not required a reoperation and that had been followed for an average of 121 months were also measured. RESULTS: Loosening of the socket was radiographically identified by (1) radiolucent lines that initially appeared after two years, (2) progression of radiolucent lines after two years, (3) radiolucent lines in all three zones, (4) radiolucent lines 2 mm or wider in any zone, or (5) migration. The sensitivity of these criteria was 94%, and the specificity was 100%. The criteria had a positive predictive value of 100% and a negative predictive value of 97%. CONCLUSIONS: The most predictive radiographic findings for early diagnosis of loosening of a hemispheric porous-coated cup were progression of radiolucent lines more than two years after the operation and any new radiolucent line of 1 mm or wider that appeared more than two years postoperatively. Sequential anteroposterior and lateral radiographs are necessary to assess the time of onset and progression of radiolucent lines in order to identify loose hemispheric porous-coated cups accurately.

Total hip arthroplasties in patients less than forty-five years old.

We studied the cases of eighty-one patients (108 total hip arthroplasties), ranging in age from fourteen to forty-five years, at an average of 4.5 years after the index operation and evaluated them with regard to six major factors: age, disease, Charnley category, prior operations, length of time since arthroplasty, and quality of the arthroplasty with regard to cementing technique and component position. After two to five years 78 per cent were satisfactory, but after five years or more only 72 per cent were satisfactory. Patients who were less than thirty years old had poorer results. Good technique yielded 93 per cent satisfactory clinical results. The patients in this study with the worst prognosis for success following total hip arthroplasty were less than thirty years old, had osteonecrosis or osteoarthritis as the primary disease, and had a less than optimum reconstruction. Patients who were alcohol-abusers or who had had a prior hip infection or a prior acetabular cup or femoral hemiarthroplasty also had a poor prognosis. Patients who had the arthroplasty for collagen disease or were thirty years old or older, or both, and had a good technical reconstruction had the best prognosis.

Total hip arthroplasty in protrusio acetabuli of rheumatoid arthritis.

Thirty-five total hip arthroplasties done in twenty-five patients with protrusio acetabuli secondary to rheumatoid arthritis were reviewed. There was an average follow-up of 4.3 years, with a range of three to seven years. The results were rated as excellent or good in 66 per cent, fair in 26 per cent, and poor in 8 per cent. Although 100 per cent demonstrated cementbone interface demarcation around the acetabular component, only 10 per cent showed progression of the line of demarcation to two millimeters and one had acetabular loosening with migration. Eight per cent showed femoral loosening or subsidence; 8 per cent, calcar resorption; and 6 per cent, a receding cortex with cystic changes. Twenty-three per cent had nonunion of the greater torchanter after trochanteric osteotomy. Type-III cement-bone interface demarcation was present around the acetabular component was positioned one centimeter superiorly or medially beyond the anatomical position, as estimated by the method described. In thirteen hips in which the acetabular component was positioned within five millimeters of the anatomical position, no Type-III demarcation was present. Better fixation and position of the acetabular component is achieved by the use of a bone graft or a special titanium perforated-sheet mesh, or both, or by an acetabular shell. The use of three wires improved trochanteric fixation.

Medial protrusio technique for placement of a porous-coated, hemispherical acetabular component without cement in a total hip arthroplasty in patients who have acetabular dysplasia.

Twenty-four hip replacements were performed with use of a medial protrusio technique to stabilize the fit of a hemispherical metal shell in the acetabulum in nineteen patients who had dysplasia of the hip. All of the hips were followed for a minimum of five years (average, seven years; range, five to thirteen years). Six of the hips were type I, seven were type II, eight were type III, and three were type IV according to the criteria of Crowe et al. The acetabular cup was implanted with the medial aspect of its dome beyond the Kohler line (drawn from the ischium along the ilioischial line) in all hips. An autogenous graft sculpted from the femoral head was used to cover 15 to 30 percent of the superolateral portion of the cup in one type-I hip, four type-III hips, and one type-IV hip. The need for these six bone grafts could have been avoided by reaming two to three millimeters more medially or by allowing 20 percent of the superolateral portion of the cup to be uncovered. Sixty to 84 percent of each bone graft was resorbed, effectively leaving the superolateral portion of the cup uncovered. The amount of the surface of the cup that was beyond the Kohler line averaged 41 percent for the six type-I hips, 43 percent for the seven type-II hips, 41 percent for six of the type-III hips, and 44 percent for one of the type-IV hips. Crossing of the ilioischial and iliopubic lines was noted on the radiographs of two type-III and two type-IV hips. Radiographs of two type-I hips and one type-II hip showed 7 to 17 percent of the surface of the dome of the cup through the internal pelvic wall (beyond the iliopubic line). None of the twenty-four metal shells were revised. A reoperation was performed on two hips to exchange a worn polyethylene insert, and three femoral components that had been fixed without cement were revised because of mechanical loosening. Wear averaged 0.26 millimeter per year in the fourteen hips that had a titanium femoral head and 0.09 millimeter per year in the nine hips that had a cobalt-chromium femoral head. The remaining hip had a ceramic femoral head, and the wear rate was 0.09 millimeter per year. The medial protrusio technique is a predictable, reproducible method for obtaining fixation of a porous-coated, hemispherical acetabular component in a dysplastic acetabulum. The technique permits the use of a porous-coated (bone-ingrowth) component; avoids the use of support bone graft and thereby reduces the operative time; facilitates rehabilitation by permitting earlier weight-bearing of the hip; and permits the use of a modular bearing surface, which may allow future exchange of only this surface rather than revision of the entire acetabular component because of excessive wear.

Postmortem analysis of bone growth into porous-coated acetabular components.

Microradiography, backscattered electron microscopy, and histological analysis were used to conduct a quantitative postmortem study of seven consecutively retrieved anatomical porous replacement acetabular components that had been inserted during total hip arthroplasties. Screws had been used for the initial fixation of six components. The microradiographic analysis of all seven components showed that an average (and standard deviation) of 84 +/- 9 per cent (range, 72 to 93 per cent) of the porous coating was in direct apposition to the periprosthetic bone. The backscattered electron images demonstrated that an average of 12 +/- 6 per cent (range, 4 to 21 per cent) of the space available in the porous coating was occupied by ingrown bone. The amount of bone ingrowth was not significantly different among the three zones delineated by DeLee and Charnley. Uniformity of bone growth into the porous coating suggests that the preferential loading that occurs in the superior region did not differentially affect the bone ingrowth. The present study showed that consistent bone growth into anatomical porous replacement acetabular components can be achieved.

Total hip arthroplasty with use of the Metasul metal-on-metal articulation. Four to seven-year results.

BACKGROUND: Total hip replacements with a metal-on-metal articulation were commonly used until the mid-1970s; most were then abandoned in favor of hip replacement with a metal-on-polyethylene articulation. The reason for this change was primarily early cup loosening, which was more prevalent with these metal-on-metal designs than it was with metal-on-polyethylene designs. In the late 1980s, a metal-on-metal design with improved clearance (adequate space between the femoral head and the acetabular articulation surface to allow fluid film lubrication and clearance of any debris from within this joint), metal hardness, and reproducible surfaces was introduced by Sulzer Orthopedics in Switzerland. Orthopaedic surgeons were interested in this Metasul articulation because the contribution of polyethylene wear particles to the failure of total hip replacements had become evident. This study was undertaken to review the clinical performance of this implant and to determine if early acetabular loosening or revision and wear and osteolysis were prevalent. METHODS: Between 1991 and 1994, seventy patients (seventy hips) had a total hip replacement with the Metasul metal-on-metal articulation and a cemented Weber cup. Nine patients died less than four years after the replacement; none of these deaths were related to the operation. Five patients were not available for radiographic evaluation, but they were contacted and it was known that the hip was not painful and had not been revised. Fifty-six patients (fifty-six hips) had complete clinical and radiographic data four to 6.8 years after the operation, and they made up the study group. The patients were evaluated with use of the Harris hip score, a patient-self-assessment form, and radiographs. RESULTS: At an average of 5.2 years (range, four to 6.8 years) after the operation, the average total Harris hip score for the fifty-three patients who did not have a revision was 89.6 points (range, 62 to 100 points). The average Harris pain score was 41.0 points (range, 30 to 44 points), and the average Harris limp score was 9.4 points (range, 5 to 11 points). One patient had revision of a loose cup, but there were no other loose acetabular components in the series. Two patients had revision of the acetabular component because of dislocation. No patient had a loose or revised femoral component. Therefore, the mechanical failure rate was one (2 percent) of fifty-six patients. Thirty-six of forty-seven patients who completed the patient-self-assessment form rated their result as excellent; seven, as very good; two, as good; one, as fair; and one, as poor. Wear could not be measured on radiographs because of the metal-on-metal articulation. No hip had radiographic evidence of acetabular osteolysis and two hips had calcar resorption, but there was no other radiographic evidence of focal osteolysis. CONCLUSIONS: Our four to seven-year experience with this articulation surface indicates that the clinical results are similar to those of total hip replacements with a metal-on-polyethylene articulation. We believe that the Metasul articulation may have a role in reducing the wear that occurs with total hip replacement. The Metasul articulation appears to be particularly indicated for more active patients. A historical comparison with the reports in the literature of which we are aware indicated that the hips in our study had a lower rate of acetabular revision and loosening than did those with previous metal-on-metal designs and that they had no more acetabular loosening or osteolysis than did those with metal-on-polyethylene articulations followed for an average of five years.

The early management of open joint injuries. A prospective study of one hundred and forty patients.

A study of open joint injuries treated at the Los Angeles County-University of Southern California Medical Center from July 1969 through July 1973 showed that the vast majority of these injuries were at the knee. Three types of injury were identified: those associated with fractures, injuries without fracture, and gunshot wounds. All patients were treated with antibiotics, surgical débridement and irrigation, and installation of polyethylene tubes into the joint as a system of postoperative closed irrigation. The over-all infection rate was 2.1 per cent. The results of treatment indicate that the irrigation system can be a source of contamination. Our recommended treatment for open wounds in joints is wide-spectrum systemic antibiotics, surgical débridement, irrigation of the joint and soft tissues, and primary closure. Prolonged suction-irrigation treatment postoperatively should only be done for specific indications: excessive contamination or excessive tissue damage when the wound to the joint should be closed primarily.

Platelet activity (malondialdehyde production) after orthopaedic surgery: the effect of aspirin.

Using a biochemical assay of the prostaglandin endoperoxide metabolite malondialdehyde, platelet activity was evaluated in 147 patients who were undergoing orthopaedic surgical procedures. Assays were performed before and after operation and the results were correlated with the type of operation, the sex of the patient, and the use of aspirin as an antiplatelet-aggregation agent. Postoperatively, statistically significant elevations of platelet activity were found in patients who were not taking aspirin, while highly statistically significant suppressions of this activity were found after total hip arthroplasties and other surgical procedures in patients who had received aspirin. Men and women had similar levels of suppression of platelet aggregability with aspirin.

Clinical review of the early stability of spine injuries.

One hundred fifteen cervical fractures, 51 thoracic and lumbar major fractures, 214 compression fractures, and 34 transverse process fractures from Los Angeles County-University of Southern California Medical Center and Rancho Los Amigos Hospital were reviewed. Epidemiology, fracture type, and early results of treatment in terms of musculoskeletal and neurologic stability were studied. Flexion-rotation fractures of the cervical, thoracic, and lumbar spine showed significant loss of reduction when not treated with operative internal fixation. Operative intervention did not influence the neurologic outcome. Laminectomy resulted in progressive deformity and a significantly increased incidence of second operations. Epidemiology indicated changing patterns of fracture.

Treatment of hip fractures in elderly and senile patients.

Hip fractures in elderly and senile patients are associated with a high incidence of morbidity and mortality. For this reason, restoration of function rather than restoration of the hip must be the first concern. In senile patients with intertrochanteric fractures, condylocephalic fixations is preferred because of the decreased infection rate. In patients with severe osteoporosis, bed rest with traction as needed for comfort may be preferable. Fractures of the femoral neck in this group are best treated with percutaneous pin fixation. In the elderly ambulatory patient with no more than minimal confusion, compression screw fixation with severe osteoporosis in these patients should have adjunctive use of methylmethacrylate. In this group, fractures of the femoral neck in our experience are better treated with a cemented endoprosthesis or total hip arthroplasty.

Bone grafts for bone loss with total knee replacement.

Predictable and reproducible use of bone graft for reconstruction of defects with total knee replacement requires (1) surface preparation of host bone to expose a viable bony bed, (2) definition of the defect and preparation of the graft so that excellent fit and fixation are obtained, (3) coverage of the graft by the component to prevent resorption of unstressed graft which may compromise the press-fit of the graft and lead to failure by collapse, (4) protection of the graft from overload by correct alignment of components and limb and by limited weight-bearing until union occurs, (5) protection of the graft by use of a stemmed component when indicated. In the knee, bone grafts can be expected to be successful in 90 to 95 per cent of patients if the above principles are followed. Failed grafts can be salvaged by a second graft or by use of custom components if the bone is judged to have united.

Management of civilian gunshot injuries to the hip.

The orthopedic surgeon at a civilian trauma center is likely to encounter a gunshot injury to the hip. The nonmilitary literature regarding this injury gives few guidelines regarding an appropriate diagnostic evaluation or the indication for arthrotomy. We found that the best diagnostic test to detect joint penetration was hip aspiration followed by an arthrogram. Selected cases can be treated successfully with antibiotic therapy without an arthrotomy. These cases involve a low-velocity missile that passes through the joint, causes minimal bone disruption, and is free of bowel contaminants. If an arthrotomy is not performed, the physician must follow the patient with repeated physical examinations, complete blood counts, and a hip aspiration whenever infection is suspected. All transbdominal hip injuries require an immediate arthrotomy. In this series, bullets left in contact with joint fluid resulted in joint destruction or infection. Each patient with a displaced femoral neck fracture had a poor outcome with internal fixation. Hip arthroplasty or fusion should be considered as elective procedures for definitive management of these injuries.

The unstable total hip arthroplasty: the role of postoperative bracing.

Control of the unstable THA can be problematic, but conservative management with casting and bracing can assist the patient in gaining stability, both externally and internally. The application of such appliances does not negatively affect the ultimate function of the hip and can prevent further surgical intervention.

The bearing surface in total hip arthroplasty: evolution or revolution.

Highly cross-linked polyethylenes represent a new class of polyethylenes that demonstrate dramatic improvements of wear characteristics in laboratory tests. Cross-linked polyethylenes can be manufactured by a number of methods, all of which lead to some changes in the physical properties of the polyethylene. The very limited clinical information about cross-linked polyethylenes available has been favorable. Cross-linked polyethylenes appear to hold promise as an alternative to conventional polyethylene and to hard-on-hard bearing surfaces, but much more clinical information will be required before they can be recommended for routine clinical use.

Mobile-bearing knee replacement: concepts and results.

In summary, if TKRs are to be performed in patients who are younger and more active than those who had the initial procedures in the 1970s and 1980s, better wear performance is imperative for long-term durability, especially if surgeons continue to consider the versatility associated with modular knee-replacement systems to be a necessity. At least with some designs, including the Oxford knee and the LCS knee, the results after a minimum follow-up of 10 years are comparable with the best results after arthroplasty with fixed-bearing designs in terms of wear, loosening, and osteolysis (Table 7). As with fixed-bearing designs, there are additional challenges in terms of optimizing bearing-surface conformity and improving kinematics. Improvements in future designs of mobile-bearing total knee replacements should include better control of bearing mobility patterns to reduce the prevalence of the abnormal kinematic motions that have been observed in fluoroscopic evaluations.