Health-related quality of life after conservatively and surgically-treated paediatric proximal humeral fractures.

PURPOSE: The health-related quality of life (HRQoL) after conservatively versus surgically treated paediatric proximal humeral fractures is poorly understood. We assessed the HRQoL after this injury and asked if HRQoL was associated with age, radiological classification or treatment chosen. METHODS: We identified 228 patients who were treated for proximal humeral fractures between 2004 and 2017. These patients completed the Quick Disabilities of the Arm, Shoulder and Hand (Quick-DASH) (primary outcome), the Paediatric Quality of Life Inventory (PedsQL) and questions regarding patient satisfaction. Fractures were classified radiologically following the Paediatric Comprehensive AO Classification. RESULTS: We were able to follow-up on 190 children; 147 (mean age 8.7 years (0.8 to 15.7)) sustained a metaphyseal and 43 (mean age 11.6 years (3.7 to 15.8)) sustained a Salter Harris type I or II injury. Most fractures (90%) were simple, 10% were multifragmentary. In total, 137 children (72%) were treated nonoperatively, 51 (27%) were treated by elastic stable intramedullary nailing (ESIN). After a median follow-up of 7.6 years (0.8 to 14.3) there was an overall mean Quick-DASH of 4.3 (SD 9.3) for girls and 1.2 (SD 3.1) for boys. The mean function score of the PedsQL was 94.7 (SD 11.1) for girls and 98.0 (SD 6.0) for boys. The mean psychosocial score of the PedsQL was 92.0 (SD 11.1) for girls and 94.1 (SD 11.6) for boys. Most children (79%) were very satisfied with the cosmetic result and 74% were very satisfied with the treatment overall. Surgery and female sex were associated with lower satisfaction. CONCLUSION: In this cohort of 190 patients, where immobilization for mildly displaced fractures, and closed reduction and ESIN was used for displaced fractures, there was equally excellent mid- and long-term HRQoL when assessed by the Quick-Dash and the PedsQL. LEVEL OF EVIDENCE: Therapeutic, Level IV.

Health-related quality of life after paediatric supracondylar humeral fractures.

AIMS: We aimed to evaluate the health-related quality of life (HRQoL) in children with supracondylar humeral fractures (SCHFs), who were treated following the recommendations of the Paediatric Comprehensive AO Classification, and to assess if HRQoL was associated with AO fracture classification, or fixation with a lateral external fixator compared with closed reduction and percutaneous pinning (CRPP). METHODS: We were able to follow-up on 775 patients (395 girls, 380 boys) who sustained a SCHF from 2004 to 2017. Patients completed questionnaires including the Quick Disabilities of the Arm, Shoulder and Hand questionnaire (QuickDASH; primary outcome), and the Pediatric Quality of Life Inventory (PedsQL). RESULTS: An AO type I SCHF was most frequent (327 children; type II: 143; type III: 150; type IV: 155 children). All children with type I fractures were treated nonoperatively. Two children with a type II fracture, 136 with a type III fracture, and 141 children with a type IV fracture underwent CRPP. In the remaining 27 children with type III or IV fractures, a lateral external fixator was necessary for closed reduction. There were no open reductions. After a mean follow-up of 6.3 years (SD 3.7), patients with a type I fracture had a mean QuickDASH of 2.0 (SD 5.2), at a scale of 0 to 100, with lower values representing better HRQoL (type II: 2.8 (SD 10.7); type III: 3.3 (SD 8.0); type IV: 1.8 (SD 4.6)). The mean function score of the PedsQL ranged from 97.4 (SD 8.0) for type I to 96.1 (SD 9.1) for type III fractures, at a scale of 0 to 100, with higher values representing better HRQoL. CONCLUSION: In this cohort of 775 patients in whom nonoperative treatment was chosen for AO type I and II fractures and CRPP or a lateral external fixator was used in AO type III and IV fractures, there was equally excellent mid- and long-term HRQoL when assessed by the QuickDASH and PedsQL. These results indicate that the treatment protocol followed in this study is unambiguous, avoids open reductions, and is associated with excellent treatment outcomes. Cite this article: Bone Joint J 2020;102-B(6):755-765.

Health-related Quality of Life After Fractures of the Lateral Third of the Clavicle in Children and Adolescents.

INTRODUCTION: The health-related quality of life after pediatric fractures of the lateral third of the clavicle is unknown. Given the trend in the literature toward surgical management of clavicular fractures in adults, we frequently receive referrals for surgical management of lateral clavicular fractures in children.Therefore, we examined (1) the health-related quality of life of patients who sustained a fracture of the lateral third of the clavicle in childhood and who were treated at a large regional pediatric trauma center, (2) if the health-related quality of life was associated with the age at the time of the injury, and (3) whether fracture and displacement patterns were associated with health-related qualify of life. METHODS: This is a retrospective case series. We were able to identify 69 patients (21 girls and 48 boys) who sustained a fracture of the lateral third of the clavicle between the period spanning from January 2004 to June 2015. These patients were asked to fill in a questionnaire that included the Quick version of the Disability of Arm, Shoulder, and Hand (DASH) (primary outcome) and the Pediatric Quality of Life Inventory (Peds-QL). Until July 2017, we were able to get a response from 56 of these patients, resulting in a follow-up of 81%. RESULTS: Treatment was conservative in all cases but one. In these cases, after a mean follow-up of 6.5 years (range, 1 to 13.2 y), the mean Quick-DASH was 1.2 (SD, 4.4) at a scale of 0 to 100, with lower values representing better quality of life. The mean physical function score of the Peds-QL was 97.8 (SD, 4.4), and the mean psychosocial function score was 91.8 (SD, 10.8), both at a scale of 0 to 100, with higher values representing better quality of life.There was no statistically significant association of age at the time of injury on the primary outcome Quick-DASH.There were no statistically significant associations between fracture or displacement patterns with regard to health-related quality of life. CONCLUSIONS: Conservative treatment of lateral clavicular fractures in children and adolescents is associated with excellent health-related quality of life, as measured with the disease-specific Quick-DASH and the non-disease-specific Peds-QL at a mean follow-up of 6.5 years (range, 1 to 13.2 y). There was no effect of age at the time of injury, and we were unable to identify associations to commonly analyzed risk factors, such as displacement patterns.As the conservative treatment of this type of fracture in children and adolescents is associated with such a good health-related quality of life, it is unlikely that these results could be further improved by surgical interventions. LEVEL OF EVIDENCE: Level IV-case series.

Randomized Controlled Trials for Arthroscopy in Degenerative Knee Disease: Was Conservative Therapy Appropriately Tried Prior to Arthroscopy?

PURPOSE: We aimed to determine if the randomized controlled trials (RCTs) evaluated in the most recent meta-analysis on arthroscopic surgery for degenerative knee arthritis included documented trials of appropriate conservative treatment prior to randomization. METHODS: We selected all RCTs of the most recent meta-analysis by Brignardello-Petersen and recorded for each RCT, if physiotherapy prior to randomization was mandatory. We compared the treatment effect of arthroscopy in studies in which physiotherapy prior to randomization was mandatory versus studies in which it was not. This review was registered in the PROSPERO database (CRD42017070091). RESULTS: Of the 13 RCTs in the meta-analysis, there were 2 in which physiotherapy prior to randomization was mandatory. In 1 additional multicenter RCT, prior conservative treatment was mentioned as mandatory in the publication, but not in the protocol. The treatment effects attributed to arthroscopy in terms of short-term pain (P = .0037), short-term function (P = .0309), and long-term function (P = .0012) were larger in studies in which prior physiotherapy was mandatory. CONCLUSIONS: Although the most recent meta-analysis claims that it is based "on patients who do not respond to conservative treatment," physiotherapy was mandatory prior to randomization only in 2 of the 13 studies. As several orthopaedic guidelines recommend that the first line of treatment in patients with degenerative arthritis of the knee should be conservative, for instance with physiotherapy, and the question of performing arthroscopy arises once conservative treatment fails, 11 of the 13 RCTs failed to adhere to these accepted guidelines. Therefore, patient selection in these 11 studies may not represent the typical indications for arthroscopy, where patients have tried conservative management prior to being offered surgery. When comparing studies where prior physiotherapy was mandatory to studies in which it was not mandatory, there were statistically significant effects favoring arthroscopy in terms of pain in the short term, and for function both in the short and the long term. These findings suggest that the treatment effects attributed to arthroscopy were higher when prior physiotherapy was mandatory. Given these findings, the external validity of most of these RCTs, and the resulting "strong recommendation against the use of arthroscopy in nearly all patients with degenerative knee disease," is called into question. LEVEL OF EVIDENCE: Level II, systematic review of Level I and II studies.

Quality-Adjusted Life Years Gained by Hip and Knee Replacement Surgery and Its Aftercare.

OBJECTIVES: To determine the lifetime quality-adjusted life years (QALYs) gained by total joint arthroplasty (TJA), and assess the QALYs attributed to specific postoperative rehabilitation interventions. DESIGN: Secondary analysis of 2 multicenter, randomized controlled trials (RCTs) with 3-, 6-, 12-, and 24-month follow-up. SETTING: Two university hospitals, 2 municipal hospitals, and 1 rural hospital. PARTICIPANTS: Patients (N=827) who underwent total hip arthroplasty (THA) or total knee arthroplasty (TKA). INTERVENTIONS: RCT A: 465 patients were randomly assigned to receive aquatic therapy (pool exercises aimed at training of proprioception, coordination, and strengthening) 6 versus 14 days after THA or TKA. RCT B: 362 patients were randomly assigned to either perform or not perform ergometer cycling beginning 2 weeks after THA or TKA. MAIN OUTCOME MEASURE: QALYs, based on the Short Form-6 Dimensions utility, measured at baseline and 3, 6, 12, and 24 months' follow-up. RESULTS: After hip arthroplasty, the lifetime QALYs increased by 2.35 years in the nonergometer group, and by 2.30 years in the early aquatic therapy group. However, after knee arthroplasty, the lifetime QALYs increased by 1.81 years in the nonergometer group, and by 1.60 years in the early aquatic therapy group. By ergometer cycling, .55 additional QALYs could be gained after hip and .10 additional QALYs after knee arthroplasty, while the additional QALYs attributed to the timing of aquatic therapy were .12 years after hip and .01 years after knee arthroplasty. CONCLUSIONS: This analysis provides a sound estimate for the determination of the lifetime QALYs gained by THA and TKA. In addition, this analysis demonstrates that specific postoperative rehabilitation can result in an additional mean QALY gain of .55 years, which represents one fourth of the effect of surgery. Even if this is interpreted as a small effect at an individual level, it is important when extrapolated to all patients undergoing TJA. At a national level, these improvements appear to have a similar magnitude of QALY gain when compared with published data regarding medications to lower blood pressure in all persons with arterial hypertension.

A new universal, standardized implant database for product identification: a unique tool for arthroplasty registries.

INTRODUCTION: Every joint registry aims to improve patient care by identifying implants that have an inferior performance. For this reason, each registry records the implant name that has been used in the individual patient. In most registries, a paper-based approach has been utilized for this purpose. However, in addition to being time-consuming, this approach does not account for the fact that failure patterns are not necessarily implant specific but can be associated with design features that are used in a number of implants. Therefore, we aimed to develop and evaluate an implant product library that allows both time saving barcode scanning on site in the hospital for the registration of the implant components and a detailed description of implant specifications. MATERIALS AND METHODS: A task force consisting of representatives of the German Arthroplasty Registry, industry, and computer specialists agreed on a solution that allows barcode scanning of implant components and that also uses a detailed standardized classification describing arthroplasty components. The manufacturers classified all their components that are sold in Germany according to this classification. The implant database was analyzed regarding the completeness of components by algorithms and real-time data. RESULTS: The implant library could be set up successfully. At this point, the implant database includes more than 38,000 items, of which all were classified by the manufacturers according to the predefined scheme. Using patient data from the German Arthroplasty Registry, several errors in the database were detected, all of which were corrected by the respective implant manufacturers. CONCLUSIONS: The implant library that was developed for the German Arthroplasty Registry allows not only on-site barcode scanning for the registration of the implant components but also its classification tree allows a sophisticated analysis regarding implant characteristics, regardless of brand or manufacturer. The database is maintained by the implant manufacturers, thereby allowing registries to focus their resources on other areas of research. The database might represent a possible global model, which might encourage harmonization between joint replacement registries enabling comparisons between joint replacement registries.

Is a Revision a Revision? An Analysis of National Arthroplasty Registries' Definitions of Revision.

BACKGROUND: The reported survival of implants depends on the definition used for the endpoint, usually revision. When screening through registry reports from different countries, it appears that revision is defined quite differently. QUESTIONS/PURPOSES: The purposes of this study were to compare the definitions of revision among registry reports and to apply common clinical scenarios to these definitions. METHODS: We downloaded or requested reports of all available national joint registries. Of the 23 registries we identified, 13 had published reports that were available in English and were beyond the pilot phase. We searched these registries' reports for the definitions of the endpoint, mostly revision. We then applied the following scenarios to the definition of revision and analyzed if those scenarios were regarded as a revision: (A) wound revision without any addition or removal of implant components (such as hematoma evacuation); (B) exchange of head and/or liner (like for infection); (C) isolated secondary patella resurfacing; and (D) secondary patella resurfacing with a routine liner exchange. RESULTS: All registries looked separately at the characteristic of primary implantation without a revision and 11 of 13 registers reported on the characteristics of revisions. Regarding the definition of revision, there were considerable differences across the reports. In 11 of 13 reports, the primary outcome was revision of the implant. In one registry the primary endpoint was "reintervention/revision" while another registry reported separately on "failure" and "reoperations". In three registries, the definition of the outcome was not provided, however in one report a results list gave an indication for the definition of the outcome. Wound revision without any addition or removal of implant components (scenario A) was considered a revision in three of nine reports that provided a clear definition on this question, whereas two others did not provide enough information to allow this determination. Exchange of the head and/or liner (like for infection; scenario B) was considered a revision in 11 of 11; isolated secondary patella resurfacing (scenario C) in six of eight; and secondary patella resurfacing with routine liner exchange (scenario D) was considered a revision in nine of nine reports. CONCLUSIONS: Revision, which is the most common main endpoint used by arthroplasty registries, is not universally defined. This implies that some reoperations that are considered a revision in one registry are not considered a revision in another registry. Therefore, comparisons of implant performance using data from different registries have to be performed with caution. We suggest that registries work to harmonize their definitions of revision to help facilitate comparisons of results across the world's arthroplasty registries.

[Registries as a tool for optimizing safety of endoprostheses. Experiences from other countries and the setup of the German arthroplasty register]. / Register als Werkzeug für mehr Endoprothesensicherheit. Erfahrungen aus anderen Ländern und dem Aufbau des Endoprothesenregisters Deutschland.

There has previously been no structured long-term documentation of the results of hip and knee prosthesis operations in Germany. This article presents the objectives, structure and data flow of the newly established German arthroplasty registry (EPRD). The EPRD is run as a subdivision of the German Society for Orthopedics and Orthopedic Surgery (Deutsche Gesellschaft für Orthopädie und orthopädische Chirurgie, DGOOC). It is dedicated to scientific principles and guarantees independency and immediate feedback to surgeons. The cooperation between insurance funds, hospitals, industry and scientific society is the key to success. Additional data acquisition and bureaucratic formalities are limited to a minimum and in particular there is no use of paper. Involving the health insurance funds provides access to relevant routine data. The implant documentation is facilitated by means of an implant library and barcode scanning in the operating room. The EPRD documents the survival of implants including the reasons for revision. Although the highest level of patient data protection is guaranteed, individual patients can be identified in case of implant recalls.

Better quality of life after medial versus lateral unicondylar knee arthroplasty.

BACKGROUND: The number of unicompartmental knee arthroplasties (UKAs) is growing worldwide. Because lateral UKAs are performed much less frequently than medial UKAs, the limited information leaves unclear whether UKAs have comparable survival and health-related quality of life (HRQoL) of the lateral UKA to medial UKAs. QUESTIONS/PURPOSES: We therefore compared the (1) survivorship and (2) HRQoL after lateral versus medial cemented mobile-bearing UKAs and (3) determined whether there is an association of survival to modifications of surgical technique in one of three phases. METHODS: We retrospectively reviewed 558 patients who underwent mobile-bearing UKAs from 2002 to 2009. From the records we determined revision of the joint for any reason and revision for aseptic loosening. Patients reported their physical function, pain, and stiffness as measured by the WOMAC, SF-36 physical-component summary (PCS), and Lequesne knee score. Information regarding implant survival was collected for 93% of the patients. We analyzed the patients separately by three phases based on surgical changes associated with each phase (1: initial technique; 2: improved cementing; 3: additional bone resection to ensure backward sliding of the inlay without impingement). The minimum followup was 2.1 years (mean, 6 years; range, 2.1-9.8 years). RESULTS: Implant survival was 88% at 9 years. We found similar implant survival rates for medial (90%) and lateral UKAs (83%). In all HRQoL measures, patients receiving a medial UKA had better mean scores compared with patients who had a lateral UKA: WOMAC physical function (23 versus 34, respectively) and pain (21 versus 34) and SF-36 PCS (41 versus 38). There were no survival differences by surgical phase. CONCLUSIONS: Our observations suggest a medial UKA is associated with superior HRQoL when compared with a lateral UKA, although implant survival is similar.

Multicenter randomized controlled trial comparing early versus late aquatic therapy after total hip or knee arthroplasty.

OBJECTIVE: To evaluate if the timing of aquatic therapy influences clinical outcomes after total knee arthroplasty (TKA) or total hip arthroplasty (THA). DESIGN: Multicenter randomized controlled trial with 3-, 6-, 12-, and 24-month follow-up. SETTING: Two university hospitals, 1 municipal hospital, and 1 rural hospital. PARTICIPANTS: Patients (N=465) undergoing primary THA (n=280) or TKA (n=185): 156 men, 309 women. INTERVENTION: Patients were randomly assigned to receive aquatic therapy (pool exercises aimed at training of proprioception, coordination, and strengthening) after 6 versus 14 days after THA or TKA. MAIN OUTCOME MEASURES: Primary outcome was self-reported physical function as measured by the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) at 3-, 6-, 12-, and 24-months postoperatively. Results were compared with published thresholds for minimal clinically important improvements. Secondary outcomes included the Medical Outcomes Study 36-Item Short-Form Health Survey, Lequesne-Hip/Knee-Score, WOMAC-pain and stiffness scores, and patient satisfaction. RESULTS: Baseline characteristics of the 2 groups were similar. Analyzing the total study population did not result in statistically significant differences at all follow-ups. However, when performing subanalysis for THA and TKA, opposite effects of early aquatic therapy were seen between TKA and THA. After TKA all WOMAC subscales were superior in the early aquatic therapy group, with effect sizes of WOMAC physical function ranging from .22 to .39. After THA, however, all outcomes were superior in the late aquatic therapy group, with WOMAC effect sizes ranging from .01 to .19. However, the differences between treatment groups of these subanalyses were not statistically significant. CONCLUSIONS: Early start of aquatic therapy had contrary effects after TKA when compared with THA and it influenced clinical outcomes after TKA. Although the treatment differences did not achieve statistically significance, the effect size for early aquatic therapy after TKA had the same magnitude as the effect size of nonsteroidal anti-inflammatory drugs in the treatment of osteoarthritis of the knee. However, the results of this study do not support the use of early aquatic therapy after THA. The timing of physiotherapeutic interventions has to be clearly defined when conducting studies to evaluate the effect of physiotherapeutic interventions after TKA and THA.

Women recover faster than men after standard knee arthroplasty.

BACKGROUND: Specific anatomic differences are believed to account for gender-specific function and health-related quality of life after TKA. However, there are conflicting data in the literature regarding these gender-specific outcomes, especially as woman appear to have surgery later in the course of the disease compared with men. QUESTIONS/PURPOSES: We asked whether (1) women had worse knee function and health-related quality of life after TKA compared with men, (2) lower improvements in scores, and (3) slower recovery after surgery. METHODS: Using a cohort study design, we retrospectively analyzed prospectively collected data from three multicenter randomized controlled trials evaluating rehabilitation measures after standard unisex knee arthroplasty in 494 patients (141 men and 353 women). The primary outcome was self-reported physical function as measured by the WOMAC at 3, 6, 12, and 24 months after surgery. Secondary outcomes included the pain and stiffness scales of the WOMAC and the physical and mental component summaries of the SF-36. At the time of surgery, the women were on average older (70.8 versus 67.8 years), had lower mean physical function (55 versus 47), higher mean pain scores (54 versus 48), and greater stiffness (54 versus 46) as measured by the WOMAC. RESULTS: At the 3-, 6-, 12-, and 24-month followups, men and women had similar WOMAC scores. Improvements were greater for women compared with men for WOMAC function and pain subscale scores at the 3-month (function, 28 versus 23; pain, 32 versus 25) and 6-month followups (function, 32 versus 27; pain, 36 versus 31). At the 12- and 24-month followups we noted no differences in improvement between men and women. CONCLUSION: Although women had greater functional limitations at the time of surgery than men, they recover faster early after standard TKA although function is similar at 12 and 24 months. Women also had greater improvement of WOMAC scores after standard TKA than men. LEVEL OF EVIDENCE: Level II, prognostic study. See the guidelines for authors for a complete description of levels of evidence.

Ergometer cycling after hip or knee replacement surgery: a randomized controlled trial.

BACKGROUND: The optimal treatment strategy following primary total hip or knee replacement remains unknown. The purpose of this study was to evaluate the effect of ergometer cycling after hip or knee replacement surgery on health-related quality of life and patient satisfaction. METHODS: Three hundred and sixty-two patients were randomly assigned to either perform or not perform ergometer cycling beginning two weeks after total hip or knee replacement. The primary outcome was self-reported physical function as measured with the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) at three, six, twelve, and twenty-four months postoperatively. Results were compared with published thresholds for minimal clinically important improvements. RESULTS: The baseline characteristics of the two groups were similar. After the hip arthroplasties, all of the outcome parameters were superior in the ergometer cycling group at all follow-up intervals, and the primary outcome, physical function as measured with the WOMAC, was significantly better at three months (21.6 compared with 16.4 points, effect size = 0.33, p = 0.046) and twenty-four months (14.7 compared with 9.0 points, effect size = 0.37, p = 0.019). After the hip arthroplasties, a higher percentage of the ergometer cycling group was "very satisfied" at all follow-up intervals (for example, 92% compared with 80% at three months; p = 0.027). The significant differences in the primary outcome exceeded the absolute minimal clinically important improvement threshold by a factor of 2.0. No significant differences between the study groups were seen after the knee arthroplasties. CONCLUSIONS: Ergometer cycling after total hip arthroplasty is an effective means of achieving significant and clinically important improvement in patients' early and late health-related quality of life and satisfaction. However, this study does not support the use of ergometer cycling after knee arthroplasty.

Femoral artery constriction by norepinephrine is enhanced by methylprednisolone in a rat model.

BACKGROUND: Corticosteroids are associated with femoral head osteonecrosis and arterial hypertension. The patho-mechanism of femoral head osteonecrosis is often attributed to ischemia. The aim of this study was to investigate if corticosteroids directly constrict the femoral artery or if they have a permissive effect on norepinephrine and endothelin-1-induced vasoconstriction. METHODS: Femoral artery segments were harvested from twenty Wistar rats and mounted as ring preparations on a small-vessel myograph for the purpose of making isometric force measurements. For the norepinephrine study, twenty femoral artery segments from ten rats were stimulated cumulatively with norepinephrine before and after incubation with methylprednisolone (5 mug/mL). For the endothelin-1 study, forty femoral artery segments from ten rats were used. The four artery segments from each animal were randomized by pairs to either a corticosteroid treatment group (5 mug/mL methylprednisolone incubation, n = 20) or a control group (placebo incubation, n = 18, as two of the twenty control-group vessels did not meet protocol requirements). Isometric wall tension was plotted and quantified by the EC(50) (the plasma concentration of endothelin-1 required for obtaining 50% of maximal constriction in vivo). RESULTS: In the norepinephrine-stimulated group, incubation with methylprednisolone did not directly induce any vasoconstriction but did enhance norepinephrine-elicited vasoconstriction. The norepinephrine dose-response curve displayed a shift to the left after incubation with methylprednisolone. This shift was reflected by a significantly lower mean EC50 of 9.5 x 10(-7) M +/- 5.1 x 10(-7) M after methylprednisolone incubation compared with a mean of 2.5 x 10(-6) M +/- 1.1 x 10(-6) M before incubation (p < 0.005). In the endothelin-1-stimulated group, the endothelin-1 dose-response curve displayed a tendency toward stronger contraction in the vessels that were incubated with methylprednisolone, but this tendency did not reach significance. CONCLUSIONS: Incubation with methylprednisolone enhances norepinephrine-mediated contraction of the femoral artery in a rat model. CLINICAL RELEVANCE: Vasoconstriction of the vascular bed supplying the femoral head can diminish femoral head blood flow, and this may be a factor in the early pathogenesis of corticosteroid-associated femoral head osteonecrosis.