Hip scores: A current concept review

Bilateral simultaneous hip and knee replacement: an epidemiological nationwide study from 2001 to 2016

BACKGROUND

Several studies have compared the pros and cons of simultaneous bilateral versus staged bilateral hip and knee replacement but the outcomes of these two surgical options remains a matter of controversy. This study aimed to evaluate demographic features, incidence and hospitalization rates of bilateral one stage total hip and knee arthroplasty in Italy.

METHODS

The Italian Ministry of Health's National Hospital Discharge Reports (SDO) were used to gather data. This study referred to the adult population (+ 20 years of age) from 2001 to 2015 for hip arthroplasty and from 2001 to 2016 for knee arthroplasty.

RESULTS

Overall, 1,544 bilateral simultaneous hip replacement were carried out. The incidence rate was 0.21 cases per 100,000 adult Italian residents. Male/female ratio was 1.1. The average days of hospital stay was 11.7 ± 11.8 days. The main primary codified diagnosis was: osteoarthrosis, localized, primary, pelvic region and thigh (ICD code: 715.15). 2,851 bilateral simultaneous knee replacement were carried out. The incidence rate was 0.37 cases per 100,000 adult Italian residents. Male/female ratio was 0.6. The average days of hospital stay was 7.7 ± 5.8 days. The main primary codified diagnosis was: osteoarthrosis, localized, primary, lower leg (ICD code: 715.16).

CONCLUSIONS

The burden of hip and knee osteoarthrosis as a leading cause of bilateral joint replacement is significant in Italy. The national registers' longitudinal analysis may provide data for establishing international guidelines regarding the appropriate indications for one stage bilateral simultaneous hip or knee replacement versus two stage.

Mid-term Results of Total Hip Arthroplasty for Posttraumatic Osteoarthritis after Acetabular Fracture

Purpose

The prognosis of total hip replacement (THR) after open reduction and internal fixation (ORIF) versus THR following non-operative treatment of acetabular fractures is unclear. Few studies have been conducted in this regard. Therefore, the purpose of the current study was to perform an assessment and compare the functional outcomes for study subjects in the ORIF and non-ORIF groups during the follow-up period compared to baseline.

Materials and Methods

This longitudinal comparative study, which included 40 patients who underwent THR for either posttraumatic arthritis after fixation of an acetabular fracture or arthritis following conservative management of a fracture, was conducted for 60 months. Twenty-four patients had undergone ORIF, and 16 patients had undergone nonoperative/conservative management for acetabular fractures. Following THR, the patients were followed up for monitoring of functional outcomes for the Harris hip score (HHS) and comparison between the ORIF and non-ORIF groups was performed.

Results

The HHS showed significant improvement in both ORIF and non-ORIF groups. At the end of the mean follow-up period, no significant variation in scores was observed between the groups, i.e., ORIF group (91.61±6.64) compared to non-ORIF group (85.74±11.56). A significantly higher number of re-interventions were required for medial wall fractures and combined fractures compared to posterior fractures (P<0.05).

Conclusion

THR resulted in improved functional outcome during follow-up in both the groups; however, the ORIF group was observed to have better functional outcome. Re-intervention was not required for any of the posterior fractures at the end of the mean follow-up period.

Intra-articular temperature monitoring during radiofrequency ablation in ex-vivo bovine hip joints via Fiber Bragg grating sensors

PURPOSE

Radiofrequency ablation is an increasingly used surgical option for ablation, resection and coagulation of soft tissues in joint arthroscopy. One of the major issues of thermal ablation is the temperature monitoring across the target areas, as cellular mortality is a direct consequence of thermal dosimetry. Temperatures from 45 °C to 50 °C are at risk of damage to chondrocytes. One of the most reliable tools for temperature monitoring is represented by fiber optic sensors, as they allow accurate and real-time temperature measurement via a minimally invasive approach. The aim of this study was to determine, by fiber Bragg grating sensors (FBGs), the safety of radiofrequency ablation in tissue heating applied to ex-vivo bovine hip joints.

METHODS

Ex vivo bovine hips were subjected to radiofrequency ablation, specifically in the acetabular labrum, for a total of two experiments. The WEREWOLF System (Smith + Nephew, Watford, UK) was employed in high operating mode and in a controlled ablation way. One optical fiber embedding seven FBGs was used to record multipoint temperature variations. Each sensor was 1 mm in length with a distance from edge to edge with each other of 2 mm.

RESULTS

The maximum variation was recorded in both the tests by the FBG1 (i.e., the closest one to the electrode tip) and was lower than to 2.8 °C. The other sensors (from FBG2 to FBG7) did not record a significant temperature change throughout the duration of the experiment (maximum up to 0.7 °C for FBG7).

CONCLUSIONS

No significant increase in temperature was observed at any of the seven sites. The sensor nearest to the radiofrequency source exhibited the highest temperature rise, but the variation was only 3 °C. The minimal temperature increase registered at the measurement sites, according to existing literature, is not expected to be cytotoxic. FBGs demonstrate the potential to fulfil the strict requirements for temperature measurements during arthroscopic surgery.

Revision total hip arthroplasty for aseptic loosening compared with primary total hip arthroplasty for osteoarthritis: long-term clinical, functional and quality of life outcome data

PURPOSE

The aim of this study was the comparative assessment of long-term clinical (subjective and objective), functional and quality of life outcome data between primary and revision THA.

METHODS

122 patients (130 hips) who underwent cementless revision THA of both components (TMT cup, Wagner SL stem, Zimmer Biomet) for aseptic loosening only (Group A) were compared to a matched group of 100 patients (100 hips) who underwent cementless primary THA for osteoarthritis (Synergy stem, R3 cup, Smith & Nephew) (Group B). Outcomes were evaluated with survival analysis curves, Harris Hip Score (HHS), WOMAC, Oxford Hip Score (OHS), Short-Form Health Survey (SF-12) and EQ-5D-5L scales. Mobility was assessed with walking speed, Timed Up And Go Test (TUG), Parker Mobility Score, Lower Extremity Functional Scale (LEFS) and UCLA scores.

RESULTS

At a mean follow-up of 11.1 (8-17) years a cumulative success rate of 96% (95% CI, 96-99%) in Group A and 98% (95% CI, 97-99%) in Group B with operation for any reason as an endpoint was recorded. Statistically significant differences between groups were developed for WOMAC (Mann-Whitney U-test, p = 0.014), OHS (Mann-Whitney U-test, p = 0.020) and physical component of SF-12 scores (Mann-Whitney U-test, p = 0.029) only. Group A had less improvement in function as compared with group B. In Group A, in multiple regression analysis, patients' cognition (p = 0.001), BMI (p = 0.007) and pain (p = 0.022) were found to be independent factors influencing functional recovery (WOMAC). Similarly, pain (p = 0.03) was found to influence quality of life (EQ-5D-5).

CONCLUSIONS

In the long term, revision THA shows satisfactory but inferior clinical, functional, and quality of life outcomes when compared to primary THA. Residual pain, BMI and cognitive impairment independently affect functional outcomes.

Biomechanical Gait Analysis in Patients with Osteonecrosis of the Femoral Head

Objectives  Although osteonecrosis of the femoral head is a prevalent condition, its effects on gait parameters have not been thoroughly studied and are not well-established in the current literature. The primary aim of the present study is to describe gait in patients with a diagnosis of osteonecrosis. Methods  This is a cross-sectional study. Nine patients diagnosed with osteonecrosis of the femoral head who were regularly followed-up at an outpatient clinic were selected for the present study and underwent gait analysis using Vicon Motion Capture Systems. Spatiotemporal data was obtained, and joint angles were calculated using an Euler angle coordinate system. Distal coordinate systems were used to calculate joint moments and force plates to obtain ground reaction forces. Results  Patients with osteonecrosis presented with slower velocity (0.54 m/s ± 0.19) and smaller cadence (83.01 steps/min ± 13.23) than healthy patients. The pelvic obliquity range of motion was of 10.12° ± 3.03 and rotation was of 18.23° ± 9.17. The mean hip flexion was of 9.48° ± 3.40. Ground reaction forces showed reduced braking and propelling forces. Joint moments were reduced for flexion and adduction (0.42 Nm/kg ± 0.2 and 0.30 Nm/kg ± 0.11, respectively) but the abduction moment was increased (0.42 Nm/kg ± 0.18). Conclusions  The present study showed that osteonecrosis of the femoral head presents compensatory gait mechanisms, with increased pelvic motion and decreased knee flexion to protect the hip joint. Decreased moments for hip flexion and adduction were also identified and muscle weakness for those groups may be correlated to the disease.

Patients' Perceptions and Experiences during the Pre-Admission Phase for Total Hip Replacement Surgery: A Qualitative Phenomenological Study

Osteoarthritis negatively impacts the patient's quality of life. Qualitative research is an effective tool in detecting the various emotions experienced by patients with osteoarthritis. Such studies play a crucial role in promoting comprehension of the patient's experiences of health and illness among healthcare professionals, including nurses. The purpose of this study is to examine patients' perceptions during the pre-admission process for total hip replacement (THR). The study utilized a qualitative descriptive methodology with a phenomenological approach. A sample of patients awaiting THR consented to participate in the study and were interviewed until data saturation was achieved. The results of the phenomenological analysis resulted in the identification of three themes: 1-Surgery generates mixed feelings; 2-Pain negatively impacts daily life activities; 3-Pain requires personal strategies to be alleviated. Patients awaiting THR demonstrate frustration and anxiety. They experience intense pain during daily activities, which persists even during night rest.

Total Hip Replacement: Psychometric Validation of the Italian Version of Forgotten Joint Score (FJS-12)

BACKGROUND

One million Total Hip Replacements (THA) are thought to be performed annually. To measure prosthesis awareness throughout daily activities, the FJS-12 patient-reported outcome scale was developed. This article's goal is to undertake a psychometric validation of the Italian FJS-12 among a sample of related THA patients.

METHODS

Between January and July 2019, data from 44 patients were retrieved. The participants were required to complete the Italian version of FJS-12 and of the WOMAC at preoperative follow-up, after two weeks, 1, 3, and 6 months postoperatively.

RESULTS

The Pearson correlation coefficient between the FJS-12 and WOMAC was 0.287 (p = 0.002) at preoperative follow-up, r = 0.702 (p < 0.001) at 1 month, r = 0.516 (p < 0.001) at 3 months and r = 0.585 (p < 0.001) at 6 months. The ceiling effect surpassed the acceptable range (15%) for FJS-12 in 1 month (25.5%) and WOMAC in 6 months follow-up (27.3%).

CONCLUSIONS

The psychometric validation of the Italian version of this score for THA was executed with acceptable results. FJS-12 and WOMAC reported no ceiling and floor effects. Therefore, to distinguish between patients who had good or exceptional results following UKA, the FJS-12 could be a reliable score. Under the first four months, FJS-12 had a smaller ceiling effect than WOMAC. It is recommended to use this score in clinical research concerning the outcomes of THA.

The effect of iliotibial band surgery at the hip: a systematic review

BACKGROUND

Current literature presents a variety of surgical interventions aimed at modifying the iliotibial band (ITB) at the hip to relieve lateral hip pain (LHP). However, a focus towards the hip abductors as a main driver in LHP has evolved in the last decade, which could influence the indications for isolated ITB surgery. No previous review has been undertaken to evaluate isolated ITB surgery in LHP cases.

PURPOSE

The purpose of this systematic review was to evaluate isolated ITB surgery in LHP patients in relation to pain, snapping, use of non-surgical treatments postoperatively, and repeated surgery.

METHODS

The study was reported in accordance with Preferred Reporting Items for Systematic Reviews and Meta-Analyses. The study was registered in Prospero (CRD42021216707) prior to initiation. A systematic search of literature on PubMed and Embase as well as bibliography screening on adult patients undergoing isolated ITB surgery with or without additional bursectomies was performed. Due to the lack of reliable data, no meta-analysis was performed.

RESULTS

A total of 21 studies (360 patients) were considered eligible for inclusion. The snapping and non-snapping group consisted of 150 and 210 patients, respectively. The mean follow-up time in the snapping group was 30 months and 19 months in the non-snapping group. Utilizing different surgical techniques, complete pain relief was not achieved in 12% of patients in the snapping group and 36% of the patients in the non-snapping group. In the snapping group, snapping was eliminated in 95% of patients, and five of 150 patients (3%) had repeated surgery. Eight of nine non-snapping studies reported information regarding repeated surgery, in which seven of 205 patients (3%) received repeated surgery.

CONCLUSION

ITB surgery at the hip remains widely adopted, although only level 4 studies are available, and little information exists on the long-term clinical, as well as patient reported outcomes. Based on the available data, we found indication of a positive short-term outcome in LHP with snapping regarding elimination of snapping, pain reduction, reuse of non-surgical treatment, and repeated surgery. In LHP with no snapping, we found limited evidence supporting ITB surgery based on current literature.

Epidemiology of revision hip replacement in Italy: a 15-year study

Background

Over the past two decades, there has been an increase in the amount of primary total hip arthroscopies (THA) which in turn has increased the need for THA revision surgeries. The purpose of this study was to quantify the increase in THA revision in Italy, evaluate the causes and types of THA procedures performed.

Methods

The data regarding revision hip prosthetic replacements performed both in public and private structures between 2001 and 2015 was collected by the National Hospital Discharge reports (SDO) carried out by the Italian Ministry of Health.

Results

Overall, 109,746 Revision Hip Replacements (RHR) were performed in Italy from 2001 to 2015 in the adult population. The study shows a greater number of female patients underwent surgery between 2001 and 2015 and the 75- to 79-year age group had the highest incidence of THA revision. The main causes for THA revision were found to be “Mechanical complication of internal orthopedic device implant and graft” (31.5%), “Infection and inflammatory reaction due to internal joint prosthesis” (10.5%) and “Mechanical loosening of prosthetic joint” (8.3%).

Conclusions

Revision hip replacement is growing and heavily affecting the population between 65 and 89 years and the main causes of THA revision have been quantified. The average length of hospitalization (LOS) was found to have decreased over the 14-year study period. Understanding the causes and risk factors for revision is essential in identifying avoidable complications and improving preventative care for patients undergoing primary implantation to decrease the revision burden.

Survivorship and Outcomes of Femoral Neck Preserving Stems in Primary Total Hip Arthroplasty

BACKGROUND

Short-stem femoral implants (SSFIs) promote the preservation of bone in the femoral neck, reduce soft tissue disruption, and facilitate minimally invasive surgical techniques. The purpose of this study was to report the revision rate, complication rate, patient satisfaction, patient-reported outcomes, and radiographic outcomes of patients who underwent total hip arthroplasty (THA) with the Alteon Neck Preserving Femoral Stem (ANPS).

METHODS

A prospectively maintained database was reviewed which analyzed 92 THAs between the years 2016 and 2018. Patient-reported outcomes, patient satisfaction, complication rates, and radiographic outcomes were assessed at 2-5 years postoperatively.

RESULTS

The final cohort consisted of 63 hips. Five patients (7.9%) underwent revision surgery and 2 (3.2%) had other complications not requiring revision. Survivorship when considering only the femoral component was 93.7% at an average of 41.4 months of follow-up. The average postoperative Oxford Hip Score (41.5 ± 8.3) and Harris Hip Score (77.9 ± 16.6) demonstrated significant improvement among our nonrevised patients, respectively (P < .001). Radiographs demonstrated spot welding in 56% of arthroplasties most commonly in Gruen Zones 2, 3, and 13 and that femur radiolucencies were visualized in 58% predominantly along the distal aspect of the stem. Radiographic femoral component subsidence was present in 9.7% of patients.

CONCLUSION

The ANPS may be less reliable than previously reported. Our cohort's revision rate was unacceptably high with 6.3% requiring revision surgery for femoral component loosening in less than 5 years. Surgeons should consider the challenges and prohibitive failure rate associated with SSFIs before routine usage in THA.

Influence of Depression and Sleep Quality on Postoperative Outcomes after Total Hip Arthroplasty: A Prospective Study

The trend of Total Hip Arthroplasty (THA) is projected to grow. Therefore, it has become imperative to find new measures to improve the outcomes of THA. Several studies have focused attention on the influence of psychological factors and sleep quality on surgical outcomes. The consequences of depressive states may affect outcomes and also interfere with rehabilitation. In addition, sleep quality may be an essential factor in determining surgical outcomes. To our knowledge, few articles focus on the influence of these factors on THA results. The present study investigates a possible correlation between preoperative depression or sleep quality and postoperative outcomes of THA. This study was conducted with 61 consecutive patients undergoing THA from January 2020 to January 2021. Patients were assessed preoperatively using GDS and PSQI, and six months postoperatively using FJS-12, SF-36, WOMAC, PSQI, and GDS. To simplify comparisons, the overall scores were normalized to range from 0 (worst condition) to 100 points (best condition). A total of 37 patients (60.7%) were classified as depressed and 24 as not depressed (39.3 %) in the preoperative assessment. A low–moderate positive correlation between preoperative GDS score and FJS-12 (rho = 0.22, p = 0.011), SF-36-PCS (rho = 0.328, p = 0.01), and SF-36-MCS (rho = 0.293, p = 0.022) scores at six-month follow-up was found. When the normalized preoperative GDS score was high (no depression), the FJS-12, SF-36-PCS, and SF-36-MCS scores tended to increase more compared to the other group. Statistically significant differences between the two groups were found in postoperative FJS-12 (p = 0.001), SF-36-PCS (p = 0.017), and SF-36-MCS scores (p = 0.016). No statistically significant correlation between preoperative PSQI score and postoperative outcome measures was found. Preoperatively depressed patients had a low–moderate positive correlation with postoperative SF-36 and FJS-12 scores. There was no correlation between sleep quality and postoperative outcome measures of THA.

Trends in hospitalization for pediatric hip arthroplasty: an epidemiological Nationwide study in Italy from 2001 to 2015

Background

The epidemiology of Pediatric Hip Arthroplasty (PHA) is unclear. Prevalence of PHA in Europe was reported in Scandinavian registries, but data on this procedure are not described in other countries. Therefore, it is challenging to redact a complete and valid epidemiological report on PHA in Europe. Nevertheless, national health statistics for PHA are helpful for an international audience, as different treatments are reported between countries. Moreover, sharing national statistics and correlating those to other countries’ protocols could be helpful to compare outcomes for different procedures internationally. The principal purpose is to evaluate the yearly hospital admission for PHA in Italy.

Methods

Data of this study were collected from the National Hospital Discharge Reports (SDO) reported at the Italian Ministry of Health.

Results

From 2001 to 2015, 770 PHA hospitalizations were performed in Italy, with an incidence of 0.5 procedures for every 100,000 pediatric Italian inhabitants. The average age of patients was 15.2 ± 4.6 years. The mean length of days of hospitalization was 10.9 ± 8.6 days. The majority of patients were male of 15–19 years old age group. A progressive decrease in days of hospitalizations was found during the years of the study.

Conclusions

In Europe, the incidence of hospital admission for PHA is not fully described. There is a lack of consensus on the best type of surgery to perform on young patients. Epidemiological studies are helpful to understand the national variation of a specific surgical procedure and compare them with other countries.

Implant positioning in total hip arthroplasty: influence of horizontal and vertical offset on functionality of prosthetic hip joint

PURPOSE

To analyze the effect of implant position measured in terms of offset on patient reported outcomes (PRO) following hip arthroplasty (THA).

METHODS

A total of 243 patients of the total hip replacement who had a one year follow-up were included in the study. Standard both hips radiograph was used to asses post-surgery implant position in terms of horizontal offset and vertical offset, and correlated with functional outcome which was evaluated as change in PRO. i.e., Harris hip score (HHS) post-op. With center of hip rotation as reference, horizontal offset was calculated as sum of distance, of centre, from proximal femoral shaft axis and a vertical line through ipsilateral teardrop, and vertical offset as limb length discrepancy. Post-op patients were classified into three groups depending on the measurement of horizontal offset of the operated hip. The patients having operated hip horizontal offset within 5 mm of the normal hip were grouped as restored offset (RO); those having shorter or higher offset by more than 5 mm compared to normal hip were labeled as decreased (DO) or increased offset (IO) group respectively. The groups were further subdivided into suboptimal and optimal function groups based on HHS, and among these groups, limb length discrepancy was evaluated.

RESULTS

Post follow-up mean HHS (78.23 ± 9.96) improved significantly in all three groups (p < 0.0001). The difference in post-operative HHS among DO, RO, and IO groups was significant, with their averages being 72.5 ± 4.7, 82.1 ± 6.5, and 75.2 ± 4.8 respectively (p = .01). Limb length discrepancy was significantly more common in patients with suboptimal functional scores in all three groups.

CONCLUSION

This study concluded that both horizontal offset and vertical offset should be reconstructed in patients operated with unilateral THR due to hip pathology, since both factor demonstrated a comparable additive effect on clinical outcome.

Validation of the Spanish version of the Goodman score in total hip arthroplasty

Purpose

Currently, patient-reported outcome measures (PROMs) are the standard instruments used to compare arthroplasty results. Goodman et al. recently published a well-constructed scale with excellent psychometric properties that can be quickly administered. The main objective of our study was to translate, culturally adapt, and validate a Spanish version of the Goodman questionnaire in patients who underwent total hip arthroplasty (THA).

Methods

The original Goodman scale was translated into Spanish and cross-culturally adapted. Then, the data from this version were tested for psychometric quality. We designed a cross-sectional study for data collection. This study enrolled 2 institutions. Patients who underwent hip replacement due to primary osteoarthritis secondary to dysplasia between 1 January 2018 and 31 December 2019 were included. A total of 153 patients were contacted twice to record the Goodman and Oxford hip scales (OHS) to assess the validity of the questionnaire. Reliability was tested using the Cronbach’s alpha, Concordance using 3 test: intraclass correlation coefficient (ICC), Lin's concordance correlation coefficient (CCC), and the Bradley-Blackwood F test. The spearman correlation was used to asses correlation between the OHS and the Spanish-adapted Goodman scale.

Results

The overall satisfaction after THA was reported to be “very satisfied” by 137 patients (75%), and only 14 patients reported some degree of dissatisfaction (6%). The improvement in quality of life was reported to be “more than I ever dreamed possible” by 41% patients. Cronbach’s alpha was acceptable, reaching a coefficient of 0.95 (95% confidence interval, 0.82–1). No statistical difference (t test, p = 0.55) was found in the original version, with great internal validity. Test re-test concordance was optimal among the 3 tests used. A moderate correlation was found between the OHS and the Spanish-adapted Goodman scale.

Conclusion

The Spanish version of the Goodman questionnaire in THA is a reliable, consistent, and feasible scale to evaluate patient satisfaction and improvement in the quality of life in Spanish speakers.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13018-021-02653-6.

Total Hip Arthroplasty: Minimal Clinically Important Difference and Patient Acceptable Symptom State for the Forgotten Joint Score 12

The Forgotten Joint Score-12 (FJS-12) is a valid patient-reported outcome measures (PROMs) used to assess prosthesis awareness during daily activities after total hip arthroplasty (THA). The minimum clinically important difference (MCID) can be defined as the smallest change or difference that is evaluated as beneficial and could change the patient’s clinical management. The patient acceptable symptom state (PASS) is considered the minimum PROMs cut-off value that corresponds to a patient’s satisfactory state of health. Despite the validity and reliability of the FJS-12 having been already demonstrated, the MCID and the PASS of this score have not previously been defined. Patients undergoing THA from January 2019 to October 2019 were assessed pre-operatively and six months post-surgery using the FJS-12, the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) and the Oxford Hip Score (OHS). Pre-operative and follow-up questionnaires were completed by 50 patients. Both distribution-based approaches and anchor approaches were used to estimate MCID. The aim of this paper was to assess the MCID and PASS values of FJS-12 after total hip replacement. The FJS-12 MCID from baseline to 6 months post-operative follow-up was 17.5. The PASS calculated ranged from 69.8 to 91.7.

Occult Hip Prosthetic Loosening Diagnosed by [18F] Fluoride-PET/CT

Background

Positron emission tomography using the [18F] fluoride metabolite combined with computerized tomography (F-PET/CT) can be used to analyze the metabolic status of the periprosthetic bone after surgery for total hip arthroplasty.

Methods

To obtain normal PET referent values, 44 patients with 5 models of well-functioning hip prosthetic components were analyzed by F-PET/CT, radiography, and clinical score. Another group of patients having painful total hip arthroplasty, but whose radiography showed no conclusive signs of loosening, was analyzed by F-PET/CT scans before revision surgery.

Results

Preoperative median F-PET scores of the bone metabolic activity were 6.65 (3.3-9.0) for the painful stem group and 1.85 (1.2-3.9) (P < .01) for the referent group having the same stem model. At revision surgery, the stems in the painful group were assessed to be loose. At 2-year follow-up, the revised patients were all pain free.

Conclusion

F-PET/CT may be a new diagnostic tool for assessing occult loose stems that are not seen by radiography.