Robert T. Trousdale

A Systematic Approach to the Plain Radiographic Evaluation of the Young Adult Hip

Orthopaedic evaluation of hip pain in the young adult population has undergone a rapid evolution over the past decade1,2. This is in large part due to enhanced awareness of structural hip disorders, including developmental dysplasia of the hip and femoroacetabular impingement1-5. Surgical treatment for these disorders continues to be refined6-9, and our ability to identify patients along the spectrum of disease continues to improve10-15. Yet, despite our advances, obtaining an accurate diagnosis can remain challenging, especially in the setting of mild structural abnormalities. Therefore, radiographic examination is a critical component of the diagnostic evaluation and treatment decision-making process. It is essential that physicians have common and reliable radiographic views as well as parameters for plain radiographic assessment that can serve as a foundation for accurate diagnosis, disease classification, and surgical decision-making. Many different radiographic measurements have been described as indicators of structural disease. In particular, measurements such as the lateral center-edge angle of Wiberg16, the anterior center-edge angle of Lequesne17, the ac-etabular index of depth to width described by Heyman and Herndon18, the femoral head extrusion index19, and the Tonnis angle20 have been used as markers for acetabular dysplasia. Similarly, measurements of acetabular version21, the head-neck offset (initially described by Eijer)3,22, and the alpha angle19 have been used in the diagnosis of femoroacetabular impingement. Nevertheless, there is limited literature that provides comprehensive information regarding the details of radiographic evaluation in the young patient with hip symptoms. This paper summarizes the recommendations of the ANCHOR (Academic Network for Conservational Hip Outcomes Research) study group regarding the most important aspects of radiographic technique and image interpretation to evaluate the symptomatic, skeletally mature hip.

Effect of Postoperative Mechanical Axis Alignment on the Fifteen-Year Survival of Modern, Cemented Total Knee Replacements

BACKGROUND One long-held tenet of total knee arthroplasty is that implant durability is maximized when postoperative limb alignment is corrected to 0° ± 3° relative to the mechanical axis. Recently, substantial health-care resources have been devoted to computer navigation systems that allow surgeons to more often achieve that alignment. We hypothesized that a postoperative mechanical axis of 0° ± 3° would result in better long-term survival of total knee arthroplasty implants as compared with that in a group of outliers. METHODS Clinical and radiographic data were reviewed retrospectively to determine the fifteen-year Kaplan-Meier survival rate following 398 primary total knee arthroplasties performed with cement in 280 patients from 1985 to 1990. Preoperatively, most knees were in varus mechanical alignment (mean and standard deviation, 6° ± 8.8° of varus [range, 30° of varus to 22° of valgus]), whereas postoperatively most knees were corrected to neutral (mean and standard deviation, 0° ± 2.8° [range, 8° of varus to 9° of valgus]). Postoperatively, we defined a mechanically aligned group of 292 knees (with a mechanical axis of 0° ± 3°) and an outlier group of 106 knees (with a mechanical axis of beyond 0° ± 3°). RESULTS At the time of the latest follow-up, forty-five (15.4%) of the 292 implants in the mechanically aligned group had been revised for any reason, compared with fourteen (13%) of the 106 implants in the outlier group (p = 0.88); twenty-seven (9.2%) of the 292 implants in the mechanically aligned group had been revised because of aseptic loosening, mechanical failure, wear, or patellar problems, compared with eight (7.5%) of the 106 implants in the outlier group (p = 0.88); and seventeen (5.8%) of the 292 implants in the mechanically aligned group had been revised because of aseptic loosening, mechanical failure, or wear, compared with four (3.8%) of the 106 implants in the outlier group (p = 0.49). CONCLUSIONS A postoperative mechanical axis of 0° ± 3° did not improve the fifteen-year implant survival rate following these 398 modern total knee arthroplasties. We believe that describing alignment as a dichotomous variable (aligned versus malaligned) on the basis of a mechanical axis goal of 0° ± 3° is of little practical value for predicting the durability of modern total knee arthroplasty implants.

Acetabular Labral Tears Rarely Occur in the Absence of Bony Abnormalities

We evaluated the percentage of patients with acetabular labral tears who have a structural hip abnormality detectable by conventional radiography. Records from our institution from 1996 through 2002 were reviewed to identify all patients with labral tears. Patients were excluded who had classic hip dysplasia, advanced osteoarthritis, or a history of pelvic or femoral osteotomy. The hip radiographs were evaluated for abnormalities of Tönnis angle, center-edge angle of Wiberg, acetabular version, femoral neck-shaft angle, congruency between the femoral head and acetabulum, anterior femoral head-neck offset, and presence of femoral head osteophytes. Twenty-seven of the 31 patients (87%) had at least one abnormal finding and 35% had more than one abnormality. Ten patients had a retroverted acetabulum, 16 had coxa valga, 11 had an abnormal femoral head-neck offset, and 14 had osteophytes on the femoral head. Four of 31 patients (13%) had no identifiable structural abnormalities. To our knowledge, this is the first study to document that the majority of patients with labral tears have a structural hip abnormality detectable with conventional radiographs. Familiarity with these structural abnormalities is important for early detection and accurate diagnosis, and may impact optimal treatment planning and prognosis.

Factors Affecting the Durability of Primary Total Knee Prostheses

Background: Failure of total knee arthroplasty is problematic. The purpose of this study was to evaluate the factors that influence the durability of a primary total knee prosthesis.Methods: A survivorship analysis of 11,606 primary total knee arthroplasties carried out between January 1, 1978, and December 31, 2000, was performed. An analysis of patient and implant-related factors affecting survivorship was done with use of a multivariate Cox model.Results: The survivorship was 91% (95% confidence interval, 90% to 91%) at ten years (2943 knees), 84% (95% confidence interval, 82% to 86%) at fifteen years (595 knees), and 78% (95% confidence interval, 74% to 81%) at twenty years (104 knees) following the surgery. Prosthetic survivorship at ten years was 83% for patients fifty-five years of age or less compared with 94% for those older than seventy years of age (p < 0.0001), 90% for those with a diagnosis of osteoarthritis compared with 95% for those with inflammatory arthritis (p < 0.005), and 91% for those with retention of the posterior cruciate ligament compared with 76% for those with substitution of the posterior cruciate ligament (a posterior stabilized prosthesis) (p < 0.0001). Survivorship at ten years was 92% for nonmodular metal-backed tibial components, 90% for modular metal-backed tibial components, and 97% for all-polyethylene tibial components (p < 0.0001). Survivorship at ten years was 92% for prostheses fixed with cement compared with 61% for those fixed without cement (p < 0.0001).Conclusions: Significant risk factors for failure of total knee arthroplasty were the type of implant, age and gender of the patient, diagnosis, type of fixation, and design of the patellar component. In the ideal situation—treatment of a woman over the age of seventy years who has inflammatory arthritis with a nonmodular, metal-backed tibial component, cement fixation, an all-polyethylene patellar component, and retention of the posterior cruciate ligament—the ten-year survivorship of the prosthesis was estimated to be 98% (95% confidence interval, 97% to 99%).Level of Evidence: Prognostic study, Level II-1 (retrospective study). See Instructions to Authors for a complete description of levels of evidence.

Surgical Treatment of Femoroacetabular Impingement: Evaluation of the Effect of the Size of the Resection

BACKGROUND In patients with symptomatic hip impingement, surgical resection of the femoral head-neck junction may improve the range of motion and relieve pain. A risk of this procedure is fracture. We evaluated the amount of resection of the anterolateral aspect of the femoral head-neck junction that can be done safely. METHODS Cadaveric proximal femoral specimens (fifteen matched pairs) were divided into three groups: 10%, 30%, or 50% of the diameter of one femoral neck was removed, and the contralateral femoral neck was left intact to serve as the control. A compressive load was applied directly to the femoral head. Peak load, stiffness, and energy to fracture were compared among the groups. RESULTS The energy to fracture differed significantly (p = 0.0015) among the 10%, 30%, and 50% resection groups. The peak load after the 50% resection was significantly less (p = 0.0025) than that after the 10% or 30% resection. With the numbers available, there was no significant difference in peak load between the 10% and 30% resections. CONCLUSIONS Resection of up to 30% of the anterolateral quadrant of the head-neck junction did not significantly alter the load-bearing capacity of the proximal part of the femur. However, a 30% resection significantly decreased the amount of energy required to produce a fracture. Thirty percent should be considered to be the greatest feasible amount of resection because of the change in the pattern of the femoral head-neck response to axial loads that we observed.

Orthopaedic surgeon workforce and volume assessment for total hip and knee replacement in the United States: Preparing for an epidemic

The demand for health-care services in general, and musculoskeletal care in particular, is expected to increase substantially in the United States because of the growth of the population, aging of the population, public expectations, economic growth, investment in health-care interventions, and improved diagnosis and treatment. The impact of an aging population is demonstrated by the fact that, in 2000, the eleven most costly medical conditions in the United States were far more prevalent among the elderly, and the population of elderly Americans is increasing. It is not clear that the future supply of physicians will be sufficient to meet the increasing demand for health care. The supply of American physicians is limited by the aging and retirement of current physicians, medical school graduation class size of allopathic medical doctors and osteopathic physicians, and United States immigration policies, which limit the number of physicians entering the country. Furthermore, among active physicians, the “effective physician supply” is limited by gender and generational differences, lifestyle choices, changing practice patterns, and variability in physician productivity. At current physician production levels, the ratio of physicians to population will peak between 2015 and 20201. Between 2000 and 2020, the demand for orthopaedic services in this country will increase by 23% while the supply of orthopaedic surgeons will increase by only 2% during the same interval2. During the next few decades, the demand for total joint arthroplasties in the United States may not be met because of an inadequate supply of total joint arthroplasty surgeons. This hypothesis or concern is based on data and trends associated with the prevalence of total joint arthroplasty, projected volumes of total joint arthroplasty, workforce trends in total joint arthroplasty, and reimbursement for total joint arthroplasty. The purposes of this paper are to evaluate the validity of this …

Thirty-Day Mortality After Total Knee Arthroplasty

Background: There have been sporadic reports on perioperative mortality associated with total knee arthroplasty. The purpose of this study was to determine risk factors for such mortality. Methods: A computer-assisted review of the records of 22,540 consecutive patients who had undergone total knee arthroplasty between 1969 and 1997 was performed to identify all patients who had died within thirty days after the procedure. A detailed analysis of the medical, surgical, anesthetic, and pathological records of the patients was performed, and the mortality was determined according to age, gender, diagnosis, and fixation method. Results: The rate of mortality within thirty days after the operation was 0.21% (forty‐seven of 22,540). All deaths occurred in the group of 18,810 patients who had received a cemented implant, and no deaths occurred among the 3730 patients who had received an uncemented implant (p < 0.0001). The mortality rate was 0.24% (forty‐three of 18,165) after primary arthroplasty and 0.09% (four of 4375) after revision arthroplasty (p < 0.0003). Three patients (0.01%) died during the operation. Forty‐three of the forty‐seven patients who died had a history of preexisting cardiovascular and/or pulmonary disease. Simultaneous bilateral total knee arthroplasty was associated with a significantly higher rate of perioperative mortality (p < 0.002). Conclusions: Factors that were associated with a significantly increased mortality after total knee arthroplasty included an age of more than seventy years, primary (as compared with revision) knee surgery, use of a cemented prosthesis, preexisting cardiopulmonary disease, and simultaneous bilateral arthroplasty.

Muscle damage during MIS total hip arthroplasty : Smith-Petersen versus posterior approach

Decreased muscle damage is a reported benefit of minimally invasive surgical (MIS) approaches in total hip arthroplasty (THA). We compared the extent and location of muscle damage during THA using the MIS anterior Smith-Peterson and MIS posterior surgical approaches. THA was performed in six human cadavers (12 hips). One hip was assigned to the Smith-Peterson approach and the contralateral hip to the posterior approach. Muscle damage was graded with a technique of visual inspection to calculate a proportion of surface area damage. Less damage occurred in the gluteus minimus muscles and minimus tendon with the Smith-Peterson approach. A mean of 8% of the minimus muscle was damaged via the Smith-Peterson approach, compared to 18% via the posterior approach. The tensor fascia latae muscle was damaged (mean of 31%), as well as direct head of the rectus femoris (mean 12%) during the Smith-Peterson approach. The piriformis or conjoined tendon was transected in 50% of the anterior approaches to mobilize the femur. The posterior approach involved intentional detachment of the piriformis and conjoined tendon and measurable damage to the abductor muscles and gluteus minimus tendon in each specimen. Clinical outcome studies and gait analysis are necessary to ascertain the functional implications of these findings.

Acetabular retroversion is associated with osteoarthritis of the hip.

Primary osteoarthritis of the hip may have a structural basis. It was hypothesized that the radiographic appearance of acetabular retroversion could be created by altering the morphologic features of the acetabular walls, and that acetabular retroversion, as defined on an anteroposterior radiograph of the pelvis, is associated with osteoarthritis of the hip. A model pelvis was used to simulate normal, augmented, deficient, and rotated walls of the acetabulum, and radiographs were taken to compare the projections of the modified acetabular walls with the known plain radiographic appearance of a retroverted acetabulum. One hundred thirty-one good quality anteroposterior radiographs of the pelvis taken before total hip arthroplasty for idiopathic hip osteoarthritis were compared with 99 good quality radiographs taken for nonorthopaedic reasons. The prevalence of radiographic acetabular retroversion is 20% among patients with idiopathic hip osteoarthritis and 5% among the general population. The appearance of acetabular retroversion on an anteoroposterior radiograph of the pelvis is created by deficiency of the posterior wall of the acetabulum. There is a statistically significant association between radiographic acetabular retroversion and hip osteoarthritis. These findings have applicability to understanding the mechanical etiology of hip osteoarthritis, and to surgical technique during periacetabular osteotomy and total hip arthroplasty.

Total knee arthroplasty in patients 55 years old or younger. 10- to 17-year results.

Seventy-four consecutive total knee arthroplasties in 54 patients who were 55 years of age or younger (average age 43 years) were reviewed. All patients had a minimum followup of 10 years with an average followup of 13 years (range, 10-17 years). No patients died or were lost to followup. The preoperative diagnosis was rheumatoid arthritis in 47, gonarthrosis in 12, posttraumatic arthritis in six, osteonecrosis in three, hemophilia in two, and one patient each with pigmented villonodular synovitis, tuberculosis, systemic lupus erythematosus, and achondroplasia. The knee score improved from an average of 36 points (range, 10-80 points) preoperatively to 84 points (range, 37-100 points) at latest followup. The functional score improved from 45 points (range, 0-100 points) to 60 points (range, 0-100 points) at latest followup. Two patients had their implants revised: one at 3 years because of ligamentous laxity and one at 13 years because of aseptic loosening of the tibial component. There were no deep infections. There were no radiographically loose implants at latest followup. The implant survival to revision at 10 years was estimated at 99% (confidence limit, 96%-100%). The implant survival to revision at 15 years was estimated at 95% confidence limit, 88%-100%). Cemented total knee arthroplasty in the young patient is a reliable procedure and has excellent results at 13-year followup with an estimated survivorship of 99% at 10 years.