Is a Calculated Total Hip BMD of Clinical Use?

The diagnosis of osteoporosis is based on bone mass measurement. To avoid the errors associated with the measurement of spinal bone density the total hip has been accepted as the standard measurement site. This information is not available for many early measurements. We have assessed whether it is possible to derive clinically useful information about total hip bone mineral density (BMD) from measurements at other hip sites. The bone mass measurements of 46 patients participating in a current trial of therapy for osteoporosis were reviewed. The total hip BMD as directly measured was compared with that obtained from the formula: Total hip BMD = 0.48×Neck BMD + 0.62×Trochanteric BMD + 0.03. In 30 patients with follow-up data the rate of change in hip BMD over a year was also determined by both methods. In the pretreatment state there was good agreement between the two measures (r ² = 0.96, SEE 0.012 g/cm²). If the formula was used to compute a change in total hip BMD, the agreement between both methods remained good. However, the standard error of the estimate of the change represented 59% of the observed change. This indicates that the error associated with this estimate is too great to allow clinically meaningful conclusions to be drawn from calculated total hip BMD. We conclude that, whilst it may be possible to obtain reasonable point estimates of total hip BMD from other measures in the hip, these estimates are too imprecise to allow conclusions about change in BMD to be made. Received: 27 August 1999 / Accepted: 6 November 1999     

Is it Time for Cementless Hip Resurfacing?

Background

Metal-on-metal bearing with cemented femoral component and cementless acetabular fixation is the current standard in surface replacement arthroplasty (RSA) of the hip. Because of concerns about the long-term survivorship of cemented stems in conventional hip arthroplasty, it seems logical to achieve cementless fixation on the femoral side with RSA.

Questions/Purposes

The goals of this review were to evaluate clinical and radiological data reported from previously published cementless RSA series. In addition, we intend to review author’s preliminary experience with Conserve Plus cementless devices specifically assessing the clinical outcomes, the complications rate, the survivorship, and the metallic ions levels measured in follow-up.

Methods

A references search was done with PubMed using the key words “cementless hip resurfacing”, “cementless hip resurfacing prosthesis”, and “femoral cementless hip resurfacing”. Additionally, the clinical outcomes, the complications rate, the survivorship, and the metallic ions levels were measured in 94 cementless Conserve Plus^© devices in 90 patients (68 males and 22 females) with a mean age of 41.1 years (18–59). Mean follow-up was 13.1 months (8–16).

Results

No revision was performed during the observed follow-up. Neither radiological signs of loosening nor neck narrowing >10% were evident. Chromium and cobalt levels in whole blood samples rose respectively from 0.53 μg/l (0.1–1.7) to 1.7 μg/l (0.6–2.9) and from 0.54 μg/l (0.1–1.4) to 1.98 μg/l (0.1–2.8).

Conclusions

Cementless “fit and fill” femoral-side fixation, which seems to be potentially evolved and design-related, should be considered for future hip-resurfacing device generations.     

What Is the Impact of Advancing Age on the Outcomes of Total Hip Arthroplasty?

Background

The global demand for total hip arthroplasty (THA) is increasing, underscoring its moniker as the “operation of the century.” However, debate still exists as to whether the elderly who undergo the operation achieve the same outcomes as those younger. In this study, we sought to investigate the association between older age and the risks and benefits of THA.

Late Dislocations After Total Hip Arthroplasty: Is the Bearing a Factor?

Background

Dislocation is a leading cause of revision after primary total hip arthroplasty (THA). Although more common in the first few years after the procedure, dislocation can occur at any time. This study investigated the difference in late dislocation in ceramic-on-ceramic (CoC) bearings compared with metal-on-polyethylene and ceramic-on-polyethylene bearings in THA.

Is a Higher Number of Total Hip and Knee Arthroplasty Revisions Associated With Increased Mortality?

BackgroundIt remains uncertain whether patients who undergo numerous total hip arthroplasty (THA) and/or knee arthroplasty (TKA) revisions exhibit decreased survival. Therefore, we sought to determine if the number of revisions per patient was a mortality predictor.MethodsWe retrospectively reviewed 978 consecutive THA and TKA revision patients from a single institution (from January 5, 2015-November 10, 2020). Dates of first-revision or single revision during study period and of latest follow-up or death were collected, and mortality was assessed. Number of revisions per patient and demographics corresponding to first revision or single revision were determined. Kaplan-Meier, univariate, and multivariate Cox-regressions were utilized to determine mortality predictors. The mean follow-up was 893 days (range, 3-2,658).ResultsMortality rates were 5.5% for the entire series, 5.0% among patients who only underwent TKA revision(s), 5.4% for only THA revision(s), and 17.2% for patients who underwent TKA and THA revisions (P = .019). In univariate Cox-regression, number of revisions per patient was not predictive of mortality in any of the groups analyzed. Age, body mass index (BMI), and American Society of Anesthesiologists (ASA) were significant mortality predictors in the entire series. Every 1 year of age increase significantly elevated expected death by 5.6% while per unit increase in BMI decreased the expected death by 6.7%, ASA-3 or ASA-4 patients had a 3.1 -fold increased expected death compared to ASA-1 or ASA-2 patients.ConclusionThe number of revisions a patient underwent did not significantly impact mortality. Increased age and ASA were positively associated with mortality but higher BMI was negatively associated. If health status is appropriate, patients can undergo multiple revisions without risk of decreased survival.     

What Are the Costs of Hip Osteoarthritis in the Year Prior to a Total Hip Arthroplasty?

BackgroundThe majority of the cost analysis literature on total hip arthroplasties (THAs) has been focused around the perioperative and postoperative period, with preoperative costs being overlooked.MethodsThe Humana Administrative Claims database was used to identify Medicare Advantage (MA) and Commercial beneficiaries undergoing elective primary THAs. Preoperative healthcare resource utilization in the year prior to a THA was grouped into the following categories: office visits, X-rays, magnetic resonance imagings, computed tomography scans, intra-articular steroid and hyaluronic acid injections, physical therapy, and pain medications. Total 1-year costs and per-patient average reimbursements for each category have been reported.ResultsTotal 1-year preoperative costs amounted to $21,022,883 (average = $512/patient) and $4,481,401 (average = $764/patient) for MA and Commercial beneficiaries, respectively. The largest proportion of total 1-year costs was accounted for by office visits (35% in Commercial; 41% in MA) followed by pain medications (28% in Commercial; 35% in MA). Conservative treatments (steroid injections, hyaluronic acid injections, physical therapy, and pain medications) alone accounted for 40%-44% of the total 1-year costs prior to a THA. A high healthcare utilization within the last 3 months prior to surgery was noted for opioids and steroid injections.ConclusionOn average, $500-$800/patient is spent on hip osteoarthritis-related care in the year prior to a THA. Despite their potential risks, opioids and steroid injections are often utilized in the last 3 months prior to surgery.     

Is a Total Hip Arthroplasty Stem in Varus a Risk Factor of Long-Term Mechanical Complication?

BackgroundThe impact of implanting cementless femoral stems in varus alignment on long-term mechanical complications remains poorly defined in the literature. The aim of our study was to compare survivorship and functional and radiographic outcomes of stems in varus alignment to those in neutral alignment with and average follow-up of 10 years.MethodsThis single-center, multisurgeon, retrospective case-control study compared a group of 105 total hip arthroplasty (THA) patients who had varus stem alignment (Varus Stem) to a matching group of 105 THA patients who had neutral stem alignment, operated on between January 2007 and December 2012. The primary outcome measure was implant survival. Secondary outcomes included functional (Harris Hip Score, Postel Merle d'Aubigné Score, thigh pain, dislocation and hip range of motion) and radiographic outcomes (radiolucency, osseointegration, heterotopic ossification, subsidence, and stress shielding).ResultsThere was no significant difference in implant survival between the 2 groups with 95.7% (±2.46) in the Varus Stem group versus 97.7% (±1.64) in the Neutral Stem group (P = .41) after an average follow-up of 10 years. There was no significant difference in clinical and radiographic outcomes between groups.ConclusionCementless femoral stems in varus alignment were not the cause of mechanical complications with an average follow-up of 10 years. The comparison between groups in terms of implant survival, functional, and radiographic outcomes does not show any significant differences. Positioning a femoral stem in varus alignment may be an alternative for surgeons wishing to restore preoperative offset and to ensure satisfactory hip stability.     

What Is the Impact of Body Mass Index Cutoffs on Total Hip Arthroplasty Complications?

BackgroundBody mass index (BMI) cutoffs are commonly utilized to decide whether to offer obese patients elective total hip arthroplasty (THA). However, weight loss goals may be unachievable for many, and some patients are thereby denied complication-free surgery. The purpose of this study was to assess the impact of varying BMI cutoffs on the rates of complication-free surgery after THA.MethodsPatients undergoing THA between 2015 and 2018 were identified in the American College of Surgeons National Surgical Quality Improvement Program database using Common Procedural Terminology code 27130. BMI and rates of 30-day complications were collected. BMI cutoffs of 30, 35, 40, 45, and 50 kg/m² were applied to model the incidence of complications if THA would have been allowed to proceed based on BMI.ResultsA total of 192,394 patients underwent THA, and 13,970 (7%) of them had a BMI ≥40 kg/m². With a BMI cutoff of 40 kg/m², 178,424 (92.7%) patients would have proceeded with THA. From this set, 170,296 (95.4%) would experience complication-free surgery, and 11.8% of complications would be prevented. THA would proceed for 191,217 (99.3%) patients at a BMI cutoff of 50 kg/m², of which 182,123 (95.2%) would not experience a complication, and 1.3% of complications would be prevented. Using 35 kg/m² as the BMI cutoff would prevent 28.6% of complications and permit 75.9% of complication-free surgeries to proceed.ConclusionLower BMI cutoffs for THA can result in fewer complications although they will consequentially limit access to complication-free THA. Consideration of risks of obesity in THA may be best considered as part of a holistic assessment and shared decision-making when deciding on goals for weight reduction.     

Limb Length Discrepancy in Total Hip Arthroplasty: Is the Lesser Trochanter a Reliable Measure of Leg Length?

BackgroundLimb length discrepancy (LLD) after total hip arthroplasty may affect clinical outcomes and patient satisfaction. Preoperative LLD estimates on anteroposterior pelvic radiographs fail to account for anatomical limb variation distal to the femoral reference points. The objective of this study is to determine how variations in lower limb skeletal lengths contribute to true LLD.MethodsFull-length standing anteroposterior radiographs were used to measure bilateral leg length, femoral length, and tibial length. Leg length was evaluated using 2 different proximal reference points: the center of the femoral head (COH) and the lesser trochanter (LT). Mean side-to-side discrepancy (MD) and percentage asymmetry (%AS) for each measurement were evaluated in the overall cohort and when stratified by patient demographic variables.ResultsOne hundred patients were included with an average age of 62.9 ± 11.2 years. Average femoral length was 434.0 ± 39.8 mm (MD 4.3 ± 3.5 mm) and tibial length was 379.9 ± 34.6 mm (MD 5.9 ± 12.7 mm). Average COH-talus was 817.5 ± 73.2 mm (MD 6.4 ± 5.1 mm). Average LT-talus was 760.5 ± 77.6 mm (MD 5.8 ± 5.1 mm). Absolute asymmetry >10 mm was detected in 16% of patients for COH-talus and 15% for LT-talus, while %AS >1.5% was detected in 13% of patients for COH-talus and 18% for LT-talus. Female gender was associated with increased femoral length %AS (P = .037).ConclusionApproximately 1 in 6 patients have an LLD of >10 mm when measured from either the LT or COH. Surgeons using either of these common femoral reference points to estimate LLD on pelvic radiographs should consider these findings when planning for hip reconstruction.Level of EvidenceLevel III.     

Is Routine Mid-term Total Hip Arthroplasty Surveillance Beneficial?

Background  

Routine followup of patients after primary or revision THA is commonly practiced and driven by concerns that delays in identifying early failure will result in more complicated or more costly surgical interventions. Although mid-term followup (4–10 years) has been performed to follow cohorts of patients, the benefit of observing individual patients regardless of symptoms has not been established.     

Is the Internal Rotation Lag Sign a Sensitive Test for Detecting Hip Abductor Tendon Ruptures after Total Hip Arthroplasty?

Background

A slight increase in revisions for infected joint arthroplasties has been observed in the Nordic countries since 2000 for which the reasons are unclear. However, in 2007 a Swedish study of the timing for prophylactic antibiotics in a random sample of knee arthroplasties found that only 57% of the patients had received the antibiotic during the optimal time interval 45-15 minutes before surgery. The purpose of the report was to evaluate the effect of measures taken to improve the timing of prophylactic antibiotics.

Findings

Reporting this finding to surgeons at national meetings during 2008 the Swedish Knee Arthroplasty Register (SKAR) introduced a new report form from January 2009 including the time for administration of preoperative antibiotics. Furthermore, the WHO's surgical checklist was introduced during 2009 and a national project was started to reduce infections in arthroplasty surgery (PRISS). The effect of these measures was found to be positive showing that in 2009, 69% of the 12,707 primary knee arthroplasties were reported to have received the prophylaxis within the 45-15 min time interval and 79% of the first 7,000 knee arthroplasties in 2010. A survey concerning the use of the WHO checklist at Swedish hospitals showed that 73 of 75 clinics had introduced a surgical checklist.

Conclusions

By registration and bringing back information to surgeons on the state of infection prophylaxis in combination with the introduction of the WHO checklist and the preventive work done by the PRISS project, the timing of preoperative prophylactic antibiotics in knee arthroplasty surgery was clearly improved.     

Is Cementless Total Knee Arthroplasty Safe in Women Over 75 Y of Age?

BackgroundCementless total knee arthroplasty (TKA) is the subject of renewed interest. Previous concerns about survivorship have been addressed and there is an appeal in terms of biological fixation and surgical efficiency. However, even surgeon advocates have concerns about the risk of marked subsidence when using this technology in older patients at risk for osteoporosis.MethodsThis was a retrospective analysis of 1,000 consecutive fully cementless mobile bearing TKAs performed at a single institution on women over 75 years of age who had postoperative and 1-year x-rays. The primary outcome was the incidence of subsidence.ResultsThere were three asymptomatic cases with definite subsidence and change in alignment. In a fourth symptomatic case, the femoral component subsided into varus and the tibia into valgus, thus maintaining alignment which facilitated nonoperative treatment in a 92-year-old. Overall, at 1 year, there were two- liner revisions for infection without recurrence. Five patients had further surgery, of which three were washouts and two were for periprosthetic fractures sustained postoperatively within 1 year. Seven patients had further anesthesia, of which five were manipulations and two were nonrecurrent closed reductions for spinouts.ConclusionCementless TKA did not have a high risk of subsidence in this at-risk population. In the hands of experienced surgeons, these procedures can be used safely irrespective of bone quality.     

What Is the Learning Curve for the Anterior Approach for Total Hip Arthroplasty?

Background

There are many factors that may affect the learning curve for total hip arthroplasty (THA) and surgical approach is one of these. There has been renewed interest in the direct anterior approach for THA with variable outcomes reported, but few studies have documented a surgeon’s individual learning curve when using this approach.

Questions/purposes

(1) What was the revision rate for all surgeons adopting the anterior approach for placement of a particular implant? (2) What was the revision rate for surgeons who performed > 100 cases in this fashion? (3) Is there a minimum number of cases required to complete a learning curve for this procedure?

Methods

The Australian Orthopaedic Association National Joint Replacement Registry prospectively collects data on all primary and revision joint arthroplasty surgery. We analyzed all conventional THAs performed up to December 31, 2013, with a primary diagnosis of osteoarthritis using a specific implant combination and secondarily those associated with surgeons performing more than 100 procedures. Ninety-five percent of these procedures were performed through the direct anterior approach. Procedures using this combination were ordered from earliest (first procedure date) to latest (last procedure date) for each individual surgeon. Using the order number for each surgeon, five operation groups were defined: one to 15 operations, 16 to 30 operations, 31 to 50 operations, 51 to 100 operations, and > 100 operations. The primary outcome measure was time to first revision using Kaplan-Meier estimates of survivorship.

Results

Sixty-eight surgeons performed 5499 THAs using the specified implant combination. The cumulative percent revision at 4 years for all 68 surgeons was 3% (95% confidence interval [CI], 2.5–3.8). For surgeons who had performed over 100 operations, the cumulative revision rate was 3% (95% CI, 2.0–3.5). It was not until surgeons had performed over 50 operations that there was no difference in the cumulative percent revision compared with over 100 operations. The cumulative percent revision for surgeons performing 51 to 100 operations at 4 years was 3% (95% CI, 1.5–5.4) and over 100 operations 2% (95% CI, 1.2–2.7; hazard ratio, 1.40 [95% CI, 0.7–2.7]; p = 0.33).

Conclusions

There is a learning curve for the anterior approach for THA even when using a prosthesis combination specifically marketed for that approach. We found that 50 or more procedures need to be performed by a surgeon before the rate of revision is no different from performing 100 or more procedures. Surgeons should be aware of this initial higher rate of revision when deciding which approach delivers the best outcome for their patients.     

What Works Best,a Cemented or Cementless Primary Total Hip Arthroplasty?: Minimum 17-year Followup of a Randomized Controlled Trial

Background  

Total hip arthroplasty (THA) has been associated with high survival rates, but debate remains concerning the best fixation mode of THA.     

Does Body Mass Index Influence the Outcomes and Survivorship of Modern Cementless Total Knee Arthroplasty?

BackgroundHigher body mass index (BMI) has been associated with higher rates of aseptic loosening following cemented total knee arthroplasty (TKA). However, there is a paucity of evidence on the effect of BMI on the durability of modern cementless TKA. We aimed to assess the association between BMI and clinical outcomes following cementless TKA and to determine if there was a BMI threshold beyond which the risk of revision significantly increased.MethodsWe identified 1,408 cementless TKAs of a modern design from an institutional registry. Patients were classified into BMI categories: normal (n = 136), overweight (n = 476), obese class I (n = 423), II (n = 258), and III (n = 115). The Knee Injury and Osteoarthritis Outcome Score for Joint Replacement and 12-item Short Form Health Survey scores were collected preoperatively and 2 years postoperatively. Survivorship was recorded at minimum 2 years (range, 24 to 88 months). BMI was analyzed as a continuous and categorical variable.ResultsThe improvement in patient-reported outcomes was similar across the groups. Thirty four knees (2.4%) were revised and 14 (1.0%) were for aseptic failure. Mean time-to-revision was 1.2 ± 1.3 years and did not differ across BMI categories (P = .455). Survivorship free from all-cause and aseptic revision was 97.1% and 99.0% at mean 4 years, respectively. Using Cox regression to control for demographics and bilateral procedures, BMI had no association with all-cause revision (P = .612) or aseptic revision (P = .186). Receiver operating characteristic curve analysis found no relationship between BMI and revision risk (c-statistic = 0.51).ConclusionBMI did not influence functional outcomes and survivorship of modern cementless TKA, possibly due to improved biological fixation at the bone-implant interface. Longer follow-up is necessary to confirm these findings.     

Is Range of Motion After Cruciate-Retaining Total Knee Arthroplasty Influenced by Prosthesis Design? A Prospective Randomized Trial

Improvement in knee flexion is a major expectation for many patients undergoing total knee arthroplasty (TKA). One hundred and twenty two patients were randomized to receive a cruciate-retaining standard or high-flexion TKA. Range of motion (ROM) and functional outcomes were assessed. The high flexion implants had a greater intraoperative ROM than standard implants. The mean flexion preoperatively, intraoperatively and at the one year follow-up was 107.4°, 123.0° and 108.9° in the standard group and 109.9°, 129.1° and 109.7° in the high-flexion TKA group. These differences were not significant preoperatively and at follow-up, but intraoperatively (P < 0.001). In multivariate analysis preoperative knee flexion was the only significant factor influencing knee flexion at follow-up. No differences in the Knee Society Score or SF 36 were observed.