Hip subluxation is a partial displacement of the femoral head (the ball at the top of the thighbone) from the acetabulum (the hip socket), where the two surfaces lose their normal alignment but remain in partial contact. Unlike a full dislocation, where the ball comes entirely out of the socket, a subluxated hip can still relocate with near-perfect restoration of its normal anatomy. The condition spans a wide range of severity and affects people from newborns to older adults, though the underlying causes and treatment strategies differ dramatically depending on who it affects and why.
How Subluxation Differs From Dislocation
The distinction between subluxation and dislocation matters because the two conditions carry different prognoses and call for different management. In a subluxation, the femoral head shifts partially out of the socket but maintains enough contact that, when repositioned, the joint’s anatomical landmarks line up correctly again. Surgeons often assess this by looking at a radiographic marker called Shenton’s line, a smooth arc drawn along the inner edge of the femoral neck and the upper border of the obturator foramen. In subluxation, this arc reconstitutes to near-normal when the hip is reduced; in a true dislocation, it does not.1Europe PMC. Differentiating subluxation from developmental dislocation of the hip That retained partial contact is also why subluxation is sometimes harder to detect clinically: the hip may feel “loose” or unstable without being dramatically out of place.
Causes and Risk Factors
Hip subluxation is not a single disease but a finding that can arise from several very different conditions. The cause determines who is affected, how the subluxation behaves over time, and what treatment is appropriate.
Developmental Dysplasia of the Hip
The most common cause in infants and young children is developmental dysplasia of the hip (DDH), a spectrum of hip abnormalities in which the femoral head sits abnormally within a shallow or malformed acetabulum. DDH ranges from mild instability in newborns to frank subluxation or full dislocation.2PubMed Central. Developmental Dysplasia of the Hip (DDH): Etiology, Diagnosis, and Management How the condition presents depends on age: newborns tend to show hip instability on clinical exam, infants show limited ability to spread their legs apart, and older children and adolescents may present with a limp, joint pain, or early arthritis.3PubMed Central. Developmental dysplasia of the hip Risk factors for DDH include breech positioning in the womb, family history, and being female, though the condition can occur without any identifiable risk factor.
Cerebral Palsy and Neuromuscular Conditions
Children with cerebral palsy (CP), particularly those with spastic-type CP, face a high risk of progressive hip subluxation. The mechanism is different from DDH: in CP, imbalanced muscle pull from tight hip adductors and hamstrings gradually draws the femoral head out of the socket over months to years. Because the subluxation tends to progress silently before the child complains of pain, surveillance programs that include regular physical exams and pelvic X-rays are standard in pediatric CP care.4Journal of Pediatric Orthopaedics. Soft-Tissue Release for Spastic Hip Subluxation in Cerebral Palsy The more severe the motor impairment, the greater the likelihood of hip displacement.
Hypermobility and Connective Tissue Disorders
People with inherited or acquired joint hypermobility can experience recurrent hip subluxation because the ligaments and capsule surrounding the hip are unusually lax. Whether the hypermobility comes from a defined connective tissue disorder or from a more general “bendy” phenotype, the result is the same: the capsule does not hold the femoral head snugly, leading to instability and repeated subluxation episodes.5Frontiers in Surgery. Hypermobile Disorders and Their Effects on the Hip Joint In people with hypermobile Ehlers-Danlos syndrome (hEDS), the problem can be pervasive. In one study of an hEDS cohort, roughly three-quarters reported hip subluxation at least once a week, along with frequent knee and ankle subluxations.6Clinical Biomechanics. Assessment of gait mechanics and muscle strength in hypermobile Ehlers Danlos Syndrome For these patients, subluxation is not a one-time event but a chronic, recurring problem woven into daily life.
Sports-Related Trauma
Traumatic hip subluxation in athletes is uncommon but well-documented, especially in high-impact or collision sports. A systematic review of sports-related hip dislocations and subluxations found that when surgeons later looked inside these hips arthroscopically, every single patient had a labral tear. Cartilage damage was present in over nine out of ten cases, and tears of the ligamentum teres (a small ligament inside the hip joint) were found in most patients examined for it.7PubMed Central / SAGE Journals. Hip Dislocation and Subluxation in Athletes: A Systematic Review The takeaway is that even a single subluxation event from sports trauma tends to leave behind structural damage that may need attention long after the acute episode resolves.
Symptoms and What They Feel Like
Symptoms of hip subluxation vary depending on the underlying cause, severity, and whether the subluxation is a one-time event or a chronic condition. In infants with DDH, there may be no pain at all. Instead, a parent or pediatrician notices that one leg does not move the same way as the other, or that skin folds around the thigh are asymmetric. Older children may develop a painless limp before pain sets in.
In adults and adolescents, the hallmark symptom is deep groin pain. Patients with hip microinstability often describe this pain using what clinicians call the “C sign,” where the person cups the hand over the front and side of the hip in a C shape to show where the discomfort sits.8PubMed. Microinstability of the Hip and the Splits Radiograph Some people also feel or hear a clunk as the femoral head shifts, especially during certain movements like getting out of a car, pivoting, or squatting deeply. In hypermobile patients who experience frequent subluxations, the sensation becomes familiar, sometimes described as a “giving way” or a momentary sense that the hip has shifted and then popped back.
Other common complaints include a catching sensation during movement, stiffness after sitting for a long time, and difficulty walking on uneven surfaces or slopes. Pain may radiate into the buttock or the outer thigh, which can mislead people into thinking the problem is in their lower back rather than their hip.
Diagnosis and Assessment
Diagnosing hip subluxation involves a combination of physical examination and imaging. In newborns, specific maneuvers performed during well-baby checks can detect a hip that slides in or out of the socket. For infants, ultrasound is the primary imaging tool because the hip is still largely made of cartilage and does not show up well on X-ray. After about four to six months of age, when more bone has formed, plain radiographs become useful.
In adults and older children, standard pelvic X-rays remain a first-line tool. The Shenton line mentioned earlier is one of several radiographic markers clinicians use. A systematic review of diagnostic tests found that disruption of the Shenton line moderately to highly improved the ability to diagnose hip dysplasia, increasing diagnostic accuracy by roughly 40 to 60 percent over clinical suspicion alone. For detecting instability specifically, a prone instability test improved positive diagnostic accuracy by about 38 percent.9PubMed. Accuracy of Clinical and Imaging Tests for the Diagnosis of Hip Dysplasia and Instability: A Systematic Review That same review noted that most studies in this area were of low methodological quality, so there is room for these numbers to shift as better research emerges.
MRI and CT scans are sometimes added when the clinical picture is unclear, particularly to evaluate the labrum, cartilage, and capsule. In athletes after a traumatic subluxation, an MRI is especially useful to check for the labral tears and cartilage damage that so often accompany the injury.
How Subluxation Changes the Way You Walk
Even when a subluxated hip does not cause sharp pain, it can alter how you move in subtle ways that compound over time. Research comparing the gait of people with DDH-related subluxation to healthy controls has found measurable differences in trunk posture, muscle activity, and joint loading. Patients with DDH walked with less trunk flexion, reduced knee extensor effort, and less activity in key stabilizing muscles during level and incline walking. Interestingly, during decline walking, the gluteus maximus worked harder in the DDH group, likely compensating for the hip’s instability.10Clinical Biomechanics. Multi-joint biomechanics during sloped walking in patients with developmental dysplasia of the hip
These compensations are the body’s way of protecting the unstable joint, but they come at a cost. Adjacent joints, particularly the lower back and the knee, end up absorbing loads they were not designed for. Over years, this can contribute to pain in areas seemingly unrelated to the hip, and it is one reason why clinicians look at the whole kinetic chain rather than the hip joint in isolation.
Non-Surgical Management
Not every subluxated hip needs surgery. The treatment approach depends on the cause, the patient’s age, and how much the subluxation affects function.
In infants with DDH caught early, a Pavlik harness or similar bracing device holds the hip in a flexed and abducted position, encouraging the femoral head to seat itself properly in the developing socket. Success rates are high when the condition is identified in the first few months of life, which is why newborn hip screening is routine in most countries.
For adults with mild subluxation or microinstability, especially those with hypermobility, targeted strengthening of the muscles around the hip is a cornerstone of treatment. A study of patients with dysplastic hips who performed hip abductor strengthening exercises found that muscle strength improved by about 16 percent, and pain scores improved significantly. Hip stability during dynamic activities also measurably improved.11Isokinetics and Exercise Science. Dynamic hip stability, strength and pain before and after hip abductor strengthening exercises for patients with dysplastic hips The exercises themselves are not exotic: clamshells, side-lying leg raises, and standing hip abduction with resistance bands are typical starting points. The key is consistency and progressive loading over weeks to months.
In children with cerebral palsy, non-surgical strategies have included botulinum toxin injections into the tight adductor and hamstring muscles combined with hip abduction bracing. While these interventions can improve gross motor function in the short term, longer-term follow-up has been less encouraging. A randomized trial found no additional benefit of botulinum toxin plus bracing over standard care for preventing hip displacement.12PubMed. The effect of botulinum toxin type A and a variable hip abduction orthosis on gross motor function: a randomized controlled trial A subsequent long-term study reached a similar conclusion: in children with bilateral spastic CP, early treatment with botulinum toxin and abduction bracing did not reduce the eventual need for surgery or improve hip development by the time the skeleton matured.13PubMed. The impact of botulinum toxin A and abduction bracing on long-term hip development in children with cerebral palsy This is a sobering finding and a good example of how a treatment that sounds logical in theory does not always pan out in practice.
Surgical Options
When conservative measures are not enough, or when the subluxation is too severe or progressive for bracing or exercise to make a meaningful difference, surgery enters the picture. The specific procedure depends on the anatomy of the problem.
Periacetabular Osteotomy
For adolescents and young adults with acetabular dysplasia (a socket that is too shallow to contain the femoral head properly), the Bernese periacetabular osteotomy (PAO) is one of the most commonly performed joint-preserving procedures. The surgeon makes controlled cuts in the bone around the acetabulum and repositions the socket to provide better coverage of the femoral head. A systematic review of PAO outcomes found consistent radiographic correction of the deformity and improved hip function across studies.14PubMed Central. Periacetabular osteotomy: a systematic literature review Results are best in patients with little to no existing arthritis in the joint.15PubMed. Medium-term results of the Bernese periacetabular osteotomy in the treatment of symptomatic developmental dysplasia of the hip The surgery is major, requiring several months of recovery, but when performed on the right patient it can delay or prevent the need for hip replacement decades down the road.
For hips that have both a deformed femoral head (as can occur after Legg-Calve-Perthes disease) and acetabular dysplasia, surgeons sometimes combine a surgical hip dislocation with a PAO to address both sides of the joint simultaneously. Early results from this combined approach suggest it is safe and provides significant deformity correction, though long-term data are still accumulating.16PubMed Central. Does surgical hip dislocation and periacetabular osteotomy improve pain in patients with Perthes-like deformities and acetabular dysplasia?
Arthroscopic Capsular Plication
When the instability comes primarily from a loose capsule rather than a bony deformity, an arthroscopic capsular plication may be appropriate. In this procedure, the surgeon tightens the hip capsule from within, using sutures to fold and reinforce the lax tissue. The goal is to restore the “screw-home” mechanism that normally snugs the femoral head into the socket during extension and external rotation. Published results have been good to excellent in appropriately selected patients.17Europe PMC. Arthroscopic Technique of Capsular Plication for the Treatment of Hip Instability This technique is particularly relevant for patients with hypermobility-related instability and for athletes whose capsule was stretched or torn during a traumatic subluxation event.
Soft-Tissue Surgery in Cerebral Palsy
In children with CP whose hips are progressively subluxating despite surveillance, soft-tissue releases (lengthening tight adductors and hamstrings) are often the first surgical step. If subluxation continues to progress beyond a critical threshold, bony procedures such as femoral or pelvic osteotomies become necessary. The timing and extent of surgery are guided by serial X-rays that track the percentage of the femoral head sitting outside the socket, a measurement known as the migration percentage.
Recovery After Surgery
Rehabilitation after hip preservation surgery is not a one-size-fits-all program. The specifics depend heavily on the procedure performed. After a PAO, patients typically use crutches for six to eight weeks, with restrictions on weight bearing to allow the bone cuts to heal. After an arthroscopic capsular plication, weight-bearing restrictions are shorter, but rotation and deep flexion are limited for several weeks to protect the repair.
In both cases, the rehabilitation philosophy emphasizes restoring range of motion first, then rebuilding strength, and finally returning to sport or high-demand activities. Proper postoperative rehabilitation is considered essential for optimizing functional recovery and long-term satisfaction.18Sports Health. Current Concepts in Hip Preservation Surgery: Part II–Rehabilitation Skipping stages or returning to full activity too early is a common reason for suboptimal outcomes after otherwise successful surgery.
The Long-Term Arthritis Risk
One of the most important reasons to take hip subluxation seriously, even when it causes only mild symptoms, is its link to osteoarthritis. A subluxated hip concentrates contact forces onto a smaller area of cartilage, accelerating wear. A long-term follow-up study of hips with subluxation or acetabular dysplasia found that about a third of joints that started in a pre-arthritic state progressed to early osteoarthritis within roughly nine years, and two-thirds of joints that already had early arthritis progressed to advanced-stage disease within about eight years.19PubMed. The natural course of osteoarthritis of the hip due to subluxation or acetabular dysplasia While subluxation is a significant driver of this progression, other individual factors also play a role, meaning not everyone with a subluxated hip will follow the same trajectory.20PubMed Central. Studies in osteoarthritis of the hip. 3. Congenital subluxation and osteoarthritis of the hip
This timeline underscores why joint-preserving surgeries like PAO exist. The goal is not simply to relieve today’s pain but to change the mechanical environment of the joint and slow the march toward arthritis. For a 25-year-old with a symptomatic shallow socket, a successful PAO could mean the difference between needing a hip replacement at 40 versus at 60 or later.
Labral Tears and Other Structural Damage
The labrum is a ring of cartilage that deepens the hip socket and acts as a seal, helping to maintain negative pressure inside the joint and distribute loads evenly. A subluxating hip puts enormous stress on the labrum, and tears are a common consequence. The causes of labral tears include trauma, capsular laxity, dysplasia, and degeneration, all of which are conditions that overlap heavily with the causes of subluxation itself.21Europe PMC / Springer. A comprehensive review of hip labral tears A torn labrum can become its own source of pain and mechanical symptoms (catching, clicking, sharp groin pain with pivoting), and it further destabilizes the hip by compromising the suction seal. In many cases, addressing the subluxation surgically without repairing or reconstructing the labrum leads to a disappointing result, so surgeons typically evaluate and treat both problems in the same operation when possible.
Quality of Life in Non-Ambulatory Children
Hip subluxation in children with severe cerebral palsy who do not walk raises a set of concerns that differs from those in ambulatory patients. The primary issues are pain during transfers and positioning, difficulty sitting in a wheelchair, and challenges with hygiene and caregiving. A study of non-ambulatory children with CP who underwent hip reconstructive surgery found that preoperative hip displacement correlated with worse quality-of-life scores before surgery. After correction, every percentage point of improvement in femoral head coverage corresponded to a small but measurable gain in quality-of-life scores throughout the follow-up period.22Journal of Bone and Joint Surgery. Effect of Hip Reconstructive Surgery on Health-Related Quality of Life of Non-Ambulatory Children with Cerebral Palsy For families weighing the risks of a major surgery in a child who will not walk, this finding provides evidence that the benefits extend beyond X-ray appearances and into the child’s daily comfort and their caregivers’ ability to provide care.