Idiopathic Avascular Necrosis of the Femoral Head in an Older Adult: A Case Report

Abstract

Avascular necrosis (AVN) of the femoral head is a rare but serious cause of hip pain, often presenting with non-specific symptoms that can be mistaken for more common musculoskeletal conditions. We report the case of a 65-year-old Asian male, a retired taxi driver without traditional AVN risk factors, who presented with a three-month history of progressive right hip pain - characterized as a dull, constant ache that sharpened during weight-bearing activities - and associated limping. Clinical examination revealed antalgic gait, restricted hip range of motion, and positive orthopedic tests, prompting imaging that confirmed AVN with subchondral collapse. Conservative management involving manual therapy, joint mobilization, and exercise offered only temporary symptomatic relief, and the patient eventually required total hip replacement. This case underscores the importance of careful assessment, early imaging, and multidisciplinary collaboration in managing persistent hip pain, while also highlighting the need for musculoskeletal clinicians to be vigilant for vascular pathologies and rare conditions such as AVN, particularly in older adults and those with chronic inflammatory disorders.

Introduction

Avascular necrosis (AVN) of the femoral head is a debilitating disorder resulting from compromised blood supply to the proximal femur, leading to progressive bone death and joint collapse if left untreated [1]. The femoral head is uniquely vulnerable to ischemia because it relies heavily on a limited network of terminal arteries - predominantly the circumflex femoral arteries - with minimal collateral circulation [2]. While over 80% of non-traumatic cases are secondary to well-known risk factors such as chronic steroid use or excessive alcohol consumption, AVN can also arise idiopathically [3]. Its occurrence in older adults without traditional predisposing conditions is exceedingly rare and poorly documented in current medical literature, presenting a significant diagnostic gap [4,5].

Because early stages of AVN frequently mimic benign mechanical hip conditions, patients often first present to primary-contact musculoskeletal providers [6,7]. This case highlights the clinical presentation of idiopathic AVN in a 65-year-old male, underscoring the vital need for clinicians to recognize key diagnostic "red flags" - including progressive antalgic gait, severe restrictions in hip range of motion (ROM), and positive intra-articular orthopedic tests. Documenting such atypical presentations is critical to addressing the literature gap, enhancing diagnostic vigilance, and fostering timely multidisciplinary care.

Case presentation

A 65-year-old Asian male, a retired taxi driver with 32 years of occupational history, presented to a chiropractic clinic with a chief complaint of a progressive right-sided limp that had developed over the preceding three months. The patient, a non-smoker and occasional social drinker (one to two drinks per week), reported no history of chronic steroid use, excessive alcohol consumption, trauma, or underlying medical conditions such as hypertension, diabetes mellitus, hyperlipidemia, or autoimmune disorders. Prior to symptom onset, he led an active lifestyle, engaging in daily 30-minute walks, weekly gardening, twice-weekly swimming, and weekly ballroom dancing - activities he discontinued due to his worsening condition. One year earlier, he had experienced neck pain and right arm pain, diagnosed as cervical myelopathy, which was successfully managed by the same chiropractor over six weeks with full resolution. At the time of presentation, his only medication was occasional acetaminophen (500 mg, taken as needed one to two times per week) for pain, which provided minimal relief. He sought chiropractic care to improve mobility and resume his usual activities, expressing frustration over his declining independence and social engagement.

The patient described an inability to run and noted increased limping with prolonged activity, though he could walk for up to 15 minutes without significant difficulty. He reported a dull, constant pain in the right hip, rated 4/10 on the numeric pain rating scale, which occasionally sharpened to 6/10 with radiation to the right knee, particularly during weight-bearing when symptoms peaked. Morning stiffness lasted 15-20 minutes and resolved with movement. Functional limitations included difficulty with prolonged standing (>20 minutes), stair climbing (especially descending), and entering or exiting his car, as well as challenges putting on socks and shoes due to reduced hip mobility. He denied night pain, paresthesia, or lower extremity weakness but noted that limping worsened after extended walking or standing. Self-management with over-the-counter analgesics and hot compresses offered little benefit, and he had not sought evaluation from other healthcare providers for this issue.

On physical examination, the patient exhibited an antalgic gait with a shortened right stance phase and a positive Trendelenburg sign on the right, suggesting hip abductor weakness or joint instability. Right hip ROM was notably restricted compared to the left: flexion was limited to 85° (110° left), internal rotation to 15° (35° left), external rotation to 25° (45° left), abduction to 25° (40° left), and adduction to 10° (20° left), with discomfort elicited during testing (Table 1). Palpation revealed tenderness in the right inguinal region and greater trochanter, accompanied by mild tightness in the iliopsoas, tensor fasciae latae, and gluteal muscles. Lumbar spine examination showed reduced extension (15°) and right lateral flexion (15°), with hypertonicity in the quadratus lumborum and erector spinae, likely reflecting compensatory changes. Neurological assessment was unremarkable, with intact sensation, 5/5 muscle strength bilaterally, and symmetrical reflexes. Straight leg raise was negative bilaterally, ruling out radiculopathy, but right-sided Patrick’s (flexion, abduction, and external rotation (FABER)), Scour’s, and resisted straight leg raise tests were positive, indicating hip joint pathology.

Table 1. Comparison of hip range of motion (ROM) at presentation.

Movement Axis	Right Hip (Affected)	Left Hip (Unaffected)	Associated Clinical Status
Flexion	35°	110°	Severe restriction; terminal pain
Internal Rotation	15°	35°	Mechanical block; pain
External Rotation	25°	45°	Firm end-feel; discomfort
Abduction	25°	40°	Restricted capsular pattern
Adduction	10°	20°	Restricted capsular pattern

Based on these findings, the chiropractor ordered weight-bearing X-rays of the pelvis and hips to further evaluate the suspected hip dysfunction. Imaging revealed severe right-sided osteoarthritis with notable abnormalities: the right femoral head exhibited increased radiodensity (sclerosis), flattening, and deformation, along with small cystic areas and a crescent-shaped translucent zone beneath the articular surface-classic signs of ischemic necrosis. The femoral neck appeared shortened and thickened, and the joint space was markedly narrowed (Figure 1). Suspecting AVN, the chiropractor prescribed an MRI for confirmation and initiated conservative management pending results. Treatment included soft tissue therapy (gua sha) targeting the hip external rotators, adductors, and tensor fasciae latae; joint mobilization and stretching of the hip flexors, adductors, and external rotators; chiropractic spinal manipulation of the lumbar spine (L3-L5) and sacroiliac joints; and a home exercise program emphasizing gentle hip mobility and isometric strengthening. After three sessions over one week, the patient reported a reduction in pain from 6/10 to 3/10 and an improved walking tolerance of 25 minutes.

Figure 1. Anteroposterior weight-bearing radiograph of the pelvis demonstrating subchondral sclerosis, flattening, and a characteristic "crescent sign" (subchondral radiolucent line) in the right femoral head. Note the preservation of the joint space, distinguishing advanced avascular necrosis from primary osteoarthritis (arrows).

The MRI, obtained one week later, confirmed AVN of the right femoral head, with approximately 40% of the weight-bearing surface affected and evidence of subchondral collapse (Figure 2). The chiropractor promptly referred the patient to an orthopedic surgeon, who corroborated the diagnosis of AVN of the femoral head. Initial orthopedic management included a platelet-rich plasma (PRP) injection into the right hip, complemented by three months of continued chiropractic rehabilitation focused on hip mobility, muscle strengthening, and gait optimization. During this period, pain further decreased to 4/10, and functional capacity improved moderately, allowing limited resumption of daily activities. However, repeat imaging showed progressive femoral head collapse, underscoring the structural deterioration despite symptomatic relief. After the three-month observation period, the patient and surgeon opted for total hip replacement due to persistent joint damage and its impact on quality of life. Surgery was performed successfully, and post-operative rehabilitation enabled the patient to resume normal activities within three months, albeit with mild residual restrictions in hip ROM (e.g., flexion limited to 100°). At the last follow-up, six months post-surgery, he reported no significant pain and had regained much of his prior independence, though he had not yet returned to swimming or dancing (Table 2).

Table 2. Timeline of symptom progression, red flags, and clinical management.

ROM: range of motion; AVN: avascular necrosis; SLR: straight leg raise; FABER: flexion, abduction, and external rotation

Timeline	Disease Progression and Patient Symptoms	Objective Clinical Findings and "Red Flags"	Diagnostic and Management Actions
Months 0-3	• Onset of dull, constant right hip pain (4/10) • Pain sharpens (6/10) with weight-bearing and radiates to the knee • Progressive restriction in daily activities (standing, stair climbing)	• Red Flag: Progressive antalgic gait with a shortened right stance phase • Positive Trendelenburg sign (right)	• Self-management with over-the-counter acetaminophen (500 mg, 1-2x/week) yields minimal relief
Presentation (Month 3)	• Discontinuation of all active hobbies (walking, swimming, dancing) due to mobility loss • Mild morning stiffness (15-20 mins)	• Red Flag: Severe multi-planar hip ROM restriction (Flexion limited to 35° vs. 110° left) • Red Flag: Positive intra-articular tests (FABER, Scour's, resisted SLR)	• Chiropractor orders weight-bearing X-rays • X-ray reveals classic ischemic necrosis signs (sclerosis, flattening, crescent zone) • MRI prescribed; palliative conservative management initiated
Week 1-2	• Temporary symptomatic relief • Pain decreases from 6/10 to 3/10; walking tolerance improves to 25 minutes	• Persistent structural limitations despite transient functional improvement	• Soft tissue therapy, joint mobilization, and gentle home exercises • MRI confirmation: Reveals Ficat Stage III AVN with 40% surface involvement and subchondral collapse
Months 3-6	• Stabilization of pain at 4/10 with moderate improvements in basic daily independence	• Red Flag: Repeat imaging reveals progressive structural collapse of the femoral head despite symptom management	• Immediate referral to an orthopedic surgeon • Joint management: Platelet-rich plasma (PRP) injection combined with three months of supportive chiropractic rehabilitation • Patient and surgeon opt for total hip arthroplasty (THA) due to structural decline
Months 6-12 (Post-op)	• Successful surgery and postoperative recovery • Resolution of significant hip pain • Return to normal activities and independent living	• Mild residual restriction in hip ROM (Flexion limited to 100°)	• Total hip replacement performed • Three months of post-operative physical rehabilitation • Full clinical resolution documented at six-month follow-up

Figure 2. Coronal T2-weighted MRI of the hips showing Ficat Stage III osteonecrosis of the right femoral head.

Prominent bone marrow edema is visible as diffuse hyperintensity (increased signal) across the proximal femur, accompanied by early subchondral collapse (arrow).

Discussion

This case illustrates the diagnostic and management challenges of AVN presenting as chronic hip pain in an older adult without apparent risk factors. While AVN is most commonly seen in younger, middle-aged men with clear traumatic or metabolic triggers, its occurrence in older adults without such factors remains poorly understood and is rarely described in the literature [5]. The femoral head’s unique vascular anatomy renders it especially vulnerable to ischemia, and even non-traumatic microvascular insults may play a role in idiopathic cases [6].

Clinical vigilance is essential. When evaluating patients presenting with hip complaints, the presence of the following clinical "red flags" should prompt immediate consideration of serious underlying pathology - such as AVN - beyond routine osteoarthritis or benign periarticular syndromes: persistent hip pain with progressive functional limitations; an antalgic gait or structural limp; markedly restricted ROM (especially in flexion and internal/external rotation); positive intra-articular orthopedic tests (e.g., Patrick's/FABER, Scour's). The presence of these findings warrants a low threshold for advanced imaging, particularly if initial conservative measures fail to yield lasting improvement. While X-rays may reveal late-stage changes such as sclerosis, flattening, and the crescent sign, MRI is the gold standard for early diagnosis and staging of AVN, facilitating timely referral and intervention [7].

Conservative management with manual therapy and exercise may provide temporary symptomatic relief and functional improvement in advanced cases [8]. While the literature suggests these non-surgical interventions are most effective during the early or pre-collapse stages of AVN, our case demonstrates that they are largely palliative once subchondral collapse has occurred. In advanced stages, structural deterioration typically continues despite temporary symptomatic relief, ultimately necessitating surgical intervention to restore long-term function. Clinicians should exercise high clinical vigilance when evaluating persistent hip pain. While advanced AVN is traditionally managed within orthopedic frameworks, primary-contact clinicians must remain alert to localized vascular and ischemic pathologies of the bone-even in older patients lacking traditional metabolic or traumatic risk factors [9].

A notable limitation in analyzing multi-stage clinical pathways is the presence of therapeutic confounders, which limits the ability to isolate specific causal mechanisms behind symptom progression. In this case, the patient experienced transient improvements in pain scores and walking tolerance during the initial manual therapy phase. However, because the conservative management subsequently overlapped with a PRP injection and structured home exercises prior to definitive total hip arthroplasty (THA), it is impossible to definitively attribute mid-course symptomatic fluctuations to a single intervention versus the fluctuating natural history of advanced ischemic bone disease. Clinicians must recognize that while multi-modal manual care and biological injections may provide temporary palliative relief, they do not arrest the mechanical trajectory of Ficat Stage III subchondral collapse.

This case also highlights the growing role of primary-contact musculoskeletal clinicians in the initial detection of serious joint pathology [10]. While AVN is rarely first diagnosed in chiropractic settings, awareness of red flags and timely imaging can expedite referral and optimize outcomes [11]. As aging populations maintain active lifestyles, atypical or insidious presentations may become more common, underscoring the need for multidisciplinary collaboration and education to avoid misdiagnosis or treatment delay [12].

Conclusions

This case illustrates that advanced idiopathic AVN of the femoral head can occur in an older adult completely lacking traditional metabolic or traumatic risk factors. The presentation highlights a distinct cluster of clinical red flags - specifically a progressive antalgic gait, severe multi-planar ROM restrictions, and positive intra-articular orthopedic tests - that should prompt clinicians to maintain a low threshold for advanced diagnostic imaging. Furthermore, the clinical course of this patient demonstrates that while non-surgical conservative care can achieve transient palliative symptom relief, it did not modify the disease trajectory or arrest structural decline once subchondral collapse occurred. Ultimately, timely surgical intervention via THA was necessary to restore long-term mobility and function, underscoring the importance of early diagnosis and seamless multidisciplinary referral pathways.