Arthro-CT coronal view of chondroid bodies in a right hip
Anatomic evolution is based on three stages, described by Milgram :
Stage 1: intra-synovium chondromas
Stage 2: intra-synovium and free chondromas
Stage 3: free chondromas
Concerning the first two stages, the synovium is still active, with a risk of recidivism after treatment. During the last stage, production of chondromas runs out gradually and a treatment will allow healing in most cases.
To reduce morbidity, the treatment can be realized under arthroscopic assistance. It consists in removing all foreign bodies with a synovectomy adapted to the pathology extension.
Arthroscopy will appreciate the synovial status, witness of the evolutionary stage of the illness. Biopsies will allow determining the diagnosis but also determining the activity level of the synovial chondromatosis. An active synovial chondromatosis is determined by the importance of chondroid metaplasia foci (Fig. 7.2). Between each foci, the synovium is normal, hence the importance of realizing multiple biopsies led by arthroscopy.
Arthroscopic view of chondroid metaplasia foci of the acetabular fossa in a right hip
Arthroscopic treatment of synovial chondromatosis can be considered as the reference treatment. According to the literature [1, 3, 4], it showed good to excellent results in 48–57% of the cases, with a conversion to total hip replacement (THR) in 17% at 6 years mean follow-up. However, the risk of recurrence remains high (16.2% re-arthroscopy).
Open surgery for total synovectomy shows lower recurrence rate but a higher morbidity and a higher THR conversion rate.
The extended monitoring of a synovial chondromatosis is justified by the possibility of late sarcomatous transformation. The patient should be warned that late evolution is towards secondary osteoarthritis.
Other forms of synovial chondromatosis exists :
Decalcifying form: regional radiological decalcification of the femoral head, the femoral neck and the acetabulum. The difference with algoneurodystrophy is its longer evolution, the absence of radiological blurring bone contours, little or no scintigraphic uptake and no regional bone oedema on MRI.
Retractable form: mimicking capsulitis. The joint stiffness is severe and often rebel. Chondromas are often small and within the synovium or in the rear bottom of the acetabulum.
Macromedia form or erosive pseudocystic form: one or more broad-rimmed gaps of the femoral neck near synovial reflections, which can mimic a bone cyst. These erosions are related to the pressure on the bone induced by metaplasia of synovial masses in little distensible capsular areas.
Ossified synovial form: stiffness and almost always ossified. Its functional prognosis is poor.
7.1.2 Villonodular Synovitis
Villonodular Synovitis (VNS) is usually diagnosed next to mechanical pain and blockage complains from the young adult. It is mostly a mono-articular synovitis affecting in the first position, the knee, and in the second position, the hip. MRI aspect of VNS is pathognomonic due to the presence of hemosiderin deposition with ferromagnetic properties giving a particular MRI characteristic (Fig. 7.3).
Pathognomonic hemosiderin deposition signal of a villonodular synovitis in T1-FS gadolinium MRI coronal view of the right hip
VNS can occur in two different histopathological presentations: the diffused form and the localized form.
The diffused form of VNS is characterized by a partial or total pathological synovial. It is often associated to a sero-hematic hydrarthrosis. Villi are brown or rust colour due to the presence of hemosiderin deposit (Fig. 7.4).
Treatment can be surgical synovectomy with hip dislocation or less invasive by arthroscopic synovectomy. During treatment by arthroscopy, each articular area must be methodically explored and cleaned to be as complete as possible. The main difficulty of a complete arthroscopic synovectomy is to access the posterior compartment. It is increased by the presence of blood vessels tangential to the posterior capsule inducing a high bleeding risk. Therefore, arthroscopic synovectomy cannot be total. It is only justified by its lower aggressiveness in a disease where recidivism after hip dislocation surgery is frequent (up to 50%), leading to osteoarthritis [6, 7].
Recidivism mostly occurs during the first 4 years, sometimes later, justifying an MRI monitoring. In case of recidivism, an early iterative synovectomy must be accomplished in front of the aggressiveness of the disease.
Localized form of VNS is characterized by an intra-articular pedunculated mass. It can become necrotic after a twist mechanism and engendering a mono-arthritis symptomatology.
This form of VNS needs its complete removal in a healthy area with a large excision of the pedicle to obtain healing with no risk of recidivism . This can be realized under arthroscopy.
It is important to keep in memory that an untreated localized form of VNS can evolve to a diffused form.
Arthroscopic view of the rust colour synovium of the acetabular fossa of a right hip in the case of a villonodular synovitis
7.1.3 Mechanical or Inflammatory Synovitis
During an osteoarthritic push, a significant mechanical or inflammatory synovial proliferation is often observed. Voluminous fringes can be trapped between the articular surfaces explaining phenomena of blockages . Arthro-CT or arthro-MRI can show villi of important size that can be confused with foreign bodies. The benefit of arthroscopic synovectomy in this mechanical proliferation has not been proven, and corticosteroid infiltration should be preferred. However, synovial biopsy should be performed whenever the villi have a suspicious aspect.
7.1.4 Medial Synovial Fold Pathology
Some painful hips have been described in association with a synovial fold back . This anomaly concerns the physiological structure called the medial fold or can be pathological and so named as a plicae. Such pathologies involve only a few cases, and it is necessary to stay prudent concerning this etiology for hip pain. Nevertheless, observing such anomalies during hip arthroscopy must question the surgeon on the painful potential to know when to realize its resection.
The anomaly of the medial fold is probably a conflict between itself and the iliopsoas tendon conducting to the development of a mechanical synovitis. The patient usually only complains of a widespread pain. The diagnosis cannot be established by the clinic or imaging. Only arthroscopy can observe the inflammatory area facing a thickened medial fold. The arthroscopic treatment consists in its resection with a shaver or an electrocautery device in hip flexion.
7.2 Septical Arthritis
Septical arthritis diagnostic is often established preoperatively by history, physical exam, biology, radiologic studies and, if any doubts, hip aspiration for microbiology.
Arthroscopic lavage and debridement is actually the recommended treatment for a septical hip arthritis since it is as efficient as opened surgery with lower morbidities [10, 11]. During arthroscopic treatment, multiple bacterial and anatomopathological samples are realized in the suspicious areas. The joint washing must concern the peripheral and central compartment. The excision of all suspicious septical soft tissues or synovial must be completely done with a shaver or an electrocautery device.
As soon as the samples are done, an empiric antibiotic therapy is undertaken with a multidisciplinary agreement .
Opened surgery is actually reserved to abscess lesions or to osteomyelitis.
7.3 Foreign Bodies
Cartilage or synovial origin intra-articular foreign bodies can become symptomatic. The first etiology of intra-articular chondral or osteochondral foreign bodies is synovial chondromatosis. But chondral or osteochondral fragments can also come from femoroacetabular impingement, hip trauma or osteoarthritis [12, 13]. They can be size, shape or different volume. Their numbers can be variable. It is necessary to have a proper radiological assessment such as an arthro-CT or an arthro-MRI to count, measure and localize the chondromas, osteochondromas or any other foreign bodies.
Foreign bodies can be removed under arthroscopy (Fig. 7.5). If their size is too important, they need to be fragmented prior to be removed (Fig. 7.6). Sometimes, open surgery may be necessary if the foreign bodies are too big or not fragmentable.
Arthroscopic removal of numerous chondral foreign bodies of the central compartment of the hip in synovial chondromatosis
Arthroscopic view of large osteochondral foreign body of the central compartment of a right hip that needs to be fragmented before extraction
7.4 Ligamentum Teres Pathology
7.4.1 Pathological Plicae
Some cases of pathological painful plicae have been published . The plicae were located in the acetabular fovea. Arthro-MRI can highlight a plicae by visualizing a 4–6 mm large strip between the ligamentum teres and the acetabular notch, looking as a duplication of the ligamentum teres.
Arthroscopic resection is carried out under traction, with an articulated electrocautery device introduced by the mid-anterior portal, arthroscopic control being in the anterolateral portal.
7.4.2 Ligamentum Teres Trauma
Traumas of the ligamentum teres (LT) are rare: according to the literature, 5–17.5% of patients undergoing hip arthroscopy present an LT tear . LT tear occurs next to an extension or abduction trauma hip movement.
Patients presenting LT tears complain of groin pain, blockages and instability of the hip joint. These symptoms are not specific to LT tears, which make the diagnostic difficult. A clinical test has been recently described consisting in applying internal and external rotation with a flexed hip up to 70° and 30° abduction. The test is positive when pain is induced by this manoeuvre .
X-rays are generally normal but can occasionally show a wider joint space. MRI is capable of diagnosing LT tears with high sensitivity (91%) . Concerning complete LT tears, there has been no diagnosing difference between MRI and arthro-MRI. However, arthro-MRI is more efficient concerning partial and degenerative LT tears .
Treatment can be ligamentum teres resection under arthroscopy (Fig. 7.7) with good outcomes . An arthroscopic reconstruction can also be realized : under arthroscopic visualization and fluoroscopic control, a femoral tunnel is drilled through the greater trochanter, exiting in the centre of the fovea. An acetabular tunnel is drilled through this previous femoral tunnel, with internal rotation and abduction of the hip in order to position the tunnel in the lower and slightly posteriorly portion of the acetabular fossa. A semitendinosus autograft is then pulled into the two tunnel with an endobutton positioned behind the acetabular tunnel. The graft is then fixed with an interference screw in the femoral tunnel under tension, with the hip fixed with 10° of hyperextension and 60° of external rotation.
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