Types of Loose Bodies

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Loose bodies may be ossified and non-ossified and classified as osteocartilaginous, cartilaginous, fibrous, or foreign. By far, the most commonly identified and reported loose bodies associated with the hip are ossified, mainly because they are evident on plain radiographs. As our diagnostic acumen and understanding of early hip pathology improve, the presence and significant of cartilaginous and fibrous processes within the joint will undoubtedly expand.

Osteocartilaginous loose bodies are composed of bone and cartilage, and in some cases are detectable on plain radiographs. Byrd has demonstrated the usefulness of arthroscopy in the management of loose fragments in the hip, and has reported successful debridement in a series of three young, active adults. Each patient had a successful outcome, with complete pain relief and return to full activity after an average follow-up of 22 months.1 These loose bodies may originate from several sources in the hip. The most common are os-teochondral fractures, osteochondritis dissecans, synovial os-teochondromatosis, and osteophytes (These are listed in no particular order, as the frequency of each is not extensively reported.) The classic disease process resulting in ossified bodies is synovial osteochondromatosis, which is reviewed in Chapter 14.

Osteochondral fractures are not uncommon, and result during traumatic dislocation of the hip and in association with acetabular fractures. These high-energy injuries alone place the patient at risk for aseptic necrosis of the femoral head and post-injury arthritis.2 When these insults are combined with retained bone and/or cartilage in the weightbearing articular surface, joint longevity is invariably compromised.3 When loose bodies are identified by computed tomography during closed treatment of acetabular fractures or hip dislocations, Keene and Villar advocate the early arthroscopic retrieval of traumatic loose bone fragments from the joint to eliminate further insult to the already damaged articular surface.4 Although this seems like a clear indication, Bartlett et al have reported a cardiac arrest in this situation secondary to intraabdominal extravasation of fluid through an operatively reduced, isolated double-column fracture of the acetabulum. For this reason, they do not advocate arthroscopic hip procedures for patients with acute or healing acetabular fractures.5 Philipon advocates the combination of hip arthroscopy with open reduction of acetabular fractures through an ilioinguinal approach. Loose bone and cartilage fragments can be removed from the joint prior to and during reduction, and the adequacy of the reduction can be indirectly visualized prior to final fixation.6

Osteochondritis dissecans (OCD) is a common condition in children, adolescents, and young adults that can affect any diarthrodial joint. In the hip joint, few cases have been reported as isolated lesions on both the acetabular and femoral sides of the joint.7-9 OCD is an osseous lesion with a mechanical or traumatic etiology. The process begins as avas-cular necrosis with secondary involvement of the overlying cartilage; the lesion forms a transitional zone that harbors the potential for complete healing or progression to an osseous defect. OCD is distinguished from osteochondral fractures and epiphyseal ossification disturbances by age distribution, localization, and the radiologic and surgical presentation.

Therapy is directed by symptoms and MRI findings. Lesions with intact cartilage should be managed expectantly with conservative measures. Cartilage defects with or without incomplete separation of the fragment, fluid around an undetatched fragment, or a dislodged fragment may benefit from arthros-copy with possible intervention.10 (Figure 11.1) Bowen has described the removal of loose bodies due to osteochondritis dissecans of the femoral head associated with Legg-Calve-Perthes Disease.7 Osteochondritis dissecans after skeletal maturity was reported in approximately 3% (14/465) of adults who were treated for Legg-Calve-Perthes disease as children. In asymptomatic hips, no treatment was indicated. In symptomatic patients, arthroscopic surgery of the hip was employed to remove the loose osteocartilaginous fragments. Fil-ipe et al have also reported the occurrence of loose bodies or OCD lesions in patients with a prior history of Legg-Calve-Perthes disease. They concluded that an OCD fragment should be removed surgically when it is mobile, bulging into the joint space, or when there are signs of early arthrosis.11

Loose bodies may also present in patients with degenerative arthritis, secondarily causing increased pain and mechanical symptoms. Solitary loose bodies may be present with no identifiable source, and others can be directly traced to fracture of a periarticular osteophyte. (Figure 11.2.) A patient with a symptomatic loose body in the hip and documented degenerative changes presents a treatment dilemma. The overall prognosis is usually dependent upon the extent of underlying degeneration rather than the presence or absence of a loose body. When radiographic evidence of disease is less advanced, or a young patient with a degenerative hip presents with a relatively recent onset of mechanical symptoms, ar-throscopic debridement is a potential consideration.12 This is

Symptoms Capsular ContractureArthroscopic Capsular

considered a palliative procedure to delay the ultimate need for a total hip arthroplasty, and should be combined with appropriate conservative measures. Advanced radiographic disease also precludes consideration of an arthroscopic procedure, because capsular and periarticular contracture prevents adequate distraction of the joint.

Cartilaginous loose bodies are radiolucent and in most situations originate from the articular surfaces of the femoral head and acetabulum, although they can also occur de novo in association with conditions that cause chronic synovial inflammation. These bodies are difficult to diagnosis, because radiography and plain magnetic resonance imaging usually fail to identify them.13,14 A high index of suspicion, a careful history, and a physical examination are required to direct the appropriate testing, whether CT or MR arthrography. Isolated chondral injuries are less common in the hip than in the shoulder or knee because of the constrained mechanics of the hip joint and the high energy required to cause subluxation or dislocation. The majority of reported cases describing symptomatic loose cartilaginous bodies in the hip are related to traumatic events.1,4 Significant impact loading from a direct fall on the lateral aspect of the hip, or extreme axial compression of the lower extremity that results in a subluxation or dislocation is required to cause a chondral injury in a normal hip. (Figure 11.3) Reports of hip joint exploration, open or arthroscopic, following traumatic dislocation or acetabular fracture have identified the presence of numerous cartilage fragments within the weightbearing joint surface. Avascular

Figure 11.3. Subluxation or dislocation may cause a chondral injury in a normal hip.

Figure 11.3. Subluxation or dislocation may cause a chondral injury in a normal hip.

Avascular Necrosis Femoral Head
Figure 11.4. Avascular necrosis of the femoral head may also result in the shedding of cartilaginous loose bodies or fragments.

necrosis of the femoral head may also result in the shedding of cartilaginous loose bodies or fragments. (Figure 11.4) AVN results in deterioration of the chondral surface and development of flap lesions that become acutely symptomatic. Chon-dral shedding and formation of radiolucent loose bodies and fragments also occurs during various stages of osteoarthritis and rheumatoid arthritis.12 (Figure 11.5.)

Fibrous loose bodies have been reported in other synovial joints, and have been identified in the hip more recently dur ing diagnostic arthroscopy for intractable hip pain.15 These radiolucent loose bodies result from hyalinized reactions of the synovium secondary to trauma or from chronic inflammatory conditions. Synovial thickening and impingement within the hip capsule are theorized to result in fibrosis, which with repetitive motion and impingement may become pedun-culated. These pedunculated synovial folds may detach and fall into the joint as a loose body. Conditions that result in chronic synovial inflammation (detailed in Chapter 14), such

Different Stages Arthritis
Figure 11.5. Chondral shedding and formation of radiolucent loose bodies and fragments also occurs during various stages of osteoarthritis and rheumatoid arthritis.

Figure 11.6. A fragment of a plastic cannula is retrieved arthroscopically.

Figure 11.6. A fragment of a plastic cannula is retrieved arthroscopically.

Rice Bodies Rheumatoid Arthritis

as rheumatoid arthritis, PVNS, hemophilia, tuberculosis, and synovial chondromatosis may produce multiple fibrous loose bodies known as "rice bodies." Intra-articular tumors, such as lipomas, and localized nodular synovitis may also become pedunculated and drop free into the joint.15

Foreign bodies are classified as any material not native to the human body. In the hip joint, bullets, shrapnel, needles, portions of drain tubes, and broken arthroscopic instruments have all been reported.16-22 (Figure 11.6.) Following total hip and hemiarthroplasty, broken wire and retained or entrapped polymethylmethacrylate cement have been reported and removed using arthroscopic techniques.18-20 (Figure 11.7.) Dislocations of hip implants, both in the perioperative period and later, have resulted in fragmentation of cement and generation of other foreign bodies that prevent successful closed re-duction.21,22 Arthroscopy of the joint has allowed minimally invasive removal of the objects, and significantly less morbidity than an open removal and reduction procedure.

Figure 11.7. Following total hip arthroplasty, broken wire can be removed using arthroscopic techniques.

Femoral Head Arthritis

Figure 11.7. Following total hip arthroplasty, broken wire can be removed using arthroscopic techniques.


The clinical presentation of anterior groin pain, episodes of locking, painful clicking, buckling, giving way, and/or persistent pain within the hip during activity can be associated with intra-articular loose bodies.13,23,24 The diagnosis is not difficult to overlook, given the subtle and nonspecific complaints of most patients who have had no major traumatic injury to the hip. McCarthy et al demonstrated that loose bodies within the hip joint, whether ossified or not, correlated with locking episodes with anterior inguinal pain.13,24 When considered in the differential for vague mechanical symptoms around the hip joint, the diagnosis can be determined with appropriate radiographic studies. (see Chapter 3). Examination findings are important in directing these advanced studies, because plain radiographs may be difficult to interpret with overlying phleboliths, bowel gas, bony shadows, and the relatively small size of an ossified or non-ossified loose body. In approximately one third of cases, radiodense loose bodies are apparent on plain radiographs. When the location is in question, intra-articular versus extra-articular, it can be confirmed by computed tomography when radiodense or by CT or MR arthrography when radiolucent.

Importance of Loose Body Removal

The presence of a loose body within the articulating surfaces of any joint will theoretically result in destruction of the hyaline cartilage, and ultimately result in premature arthritic degeneration. The significance of a symptomatic loose body in the hip joint should not be understated, and the treatment, ar-throscopic or open, should not be delayed.1,4 The highly congruent and constrained hip joint functions within very low tolerances and transmits loads with magnitudes reaching up to 10 times the body weight. Under these conditions, a loose body interposed between the articulating surfaces will rapidly result in damage. Epstein demonstrated a very poor prognosis associated with retained intra-articular fragments in a long-term follow-up study of patients who suffered posterior fracture dislocations of the hip.3 Santora et al have also reported the importance of loose body removal from the hips of adolescent children, and have shown good to excellent results even when the diagnosis was established late.25

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  • marco toivonen
    Why do loose bodies occur in hip?
    1 year ago
  • grossman
    Can loose body in hip be serious?
    11 months ago

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