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Fairview/Minnesota Orthopedic Sports Medicine Institute Orthopedic Fellowship Program, Minneapolis, Minnesota, U.S.A.Fairview Health Services, Minneapolis, Minnesota, U.S.A.Minnesota Orthopedic Sports Medicine Institute at Twin Cities Orthopedics, Edina, Minnesota, U.S.A.
Minimally invasive percutaneous radiofrequency ablation (RFA) techniques are the standard of care for treating simple osteoid osteomas (OOs). Historically, OOs were treated with open en bloc resection or curettage of the nidus. RFA procedures have been linked to soft-tissue complications of varying severity. In addition, RFA may be a poor choice for periarticular OOs because of the potential for procedure-related articular cartilage damage. Hip arthroscopy is a widely accepted approach for the treatment of femoroacetabular impingement. We describe arthroscopic resection of an acetabular rim–based OO as part of a rim resection and labral repair. Early clinical follow-up suggests that arthroscopic resection of an OO in this unusual location is precise and predictable, allows for an additional evaluation of associated symptomatic pathology (i.e., femoroacetabular impingement), and results in prompt symptom resolution.
See video under supplementary data.
We present a technique for arthroscopic management of an acetabulum-sided periarticular osteoid osteoma (OO) as a safe treatment alternative to radiofrequency ablation (RFA) or wide surgical excision. OO, a benign osteoblastic tumor, is most commonly found in the subcortical shaft and metaphysis of the long bones in children and represents 13% of all benign tumors.
The classic clinical symptom is perilesional pain that shows increased severity at night and is relieved by nonsteroidal anti-inflammatory drugs (NSAIDs). When the lesion is localized around the acetabulum, patients often report groin or anterior thigh pain without injury. OO is more commonly seen in male patients, aged between 5 and 25 years, with a male-female ratio of 3:1.
Untreated lesions can take more than 36 months to burn out and become symptom free. A delay in treatment of intra-articular lesions can potentially lead to osteoarthritis due to articular cartilage damage.
Several treatment strategies exist for managing OO. Historically, open surgical curettage was the preferred method of treatment. Recently, computed tomography (CT)–guided RFA has become the standard of care because of minimal postoperative complications, a low morbidity rate, minimal tissue exposure, and a rapid recovery.
Other percutaneous techniques include laser thermal therapy, cryotherapy, and ethanol therapy. For some cases, RFA remains an incomplete solution. Focal articular cartilage damage has been reported after addressing periarticular lesions in an athletic individual.
In addition, periarticular structures are identified through the arthroscope and can be carefully protected throughout the course of the procedure. Arthroscopy may be an ideal solution for patients who have concomitant symptomatic femoroacetabular impingement (FAI) and associated labral-chondral dysfunction that can be addressed concurrently with OO excision or curettage. The purpose of this article is to describe the treatment of an acetabulum-sided OO with hip arthroscopy using a ring curette, motorized burr, and careful thermal ablation in addition to treating concomitant symptomatic FAI.
Indications for arthroscopic removal of OO include periarticular lesions in which the articular cartilage surface is at risk of destruction from RFA or deep-seated lesions in which lesion localization is more challenging. In addition, in patients who have concomitant symptomatic hip pathology such as FAI, this can be addressed at the time of lesion removal by use of hip arthroscopy. The diagnosis of an OO begins with a complete history and physical examination. Patients who complain of nocturnal achy groin or thigh pain, in particular when relieved with NSAIDs, should be further evaluated with imaging modalities including plain radiographs (Fig 1), CT scans (Fig 2A), magnetic resonance imaging (MRI) (Fig 2B), or technetium 99 m bone scans. We start with plain radiographs, which can be further supplemented with MRI for soft-tissue evaluation. Often, CT is required for lesion localization and preoperative planning.
We recommend having a detailed preoperative surgical plan to improve surgical precision and efficiency, as well as to minimize traction time. Table 1 presents a step-by-step summary of the technique. We perform hip arthroscopy with the patient in the supine position (step 1) on a fracture table attachment (3080-R with Tenzor traction unit; Steris, Mentor, OH). An image intensifier is used to assess positioning and evaluate osseous morphology (step 2). The hip is then distracted, and prepositioning of the anterolateral portal is completed with a 6-inch, 17-gauge arthroscopic needle (Smith & Nephew). Appropriate intra-articular position is verified on the image intensifier. A 1.2-mm × 18-inch nitinol guidewire (Smith & Nephew) is then placed through the needle. After needle removal, a 5.0-mm cannula with an obturator (Smith & Nephew) is passed over the wire, and the joint is assessed with a 70° arthroscope (Smith & Nephew). Before joint insufflation, the midanterior portal is established in a similar fashion. A posterolateral gravity outflow portal is created with a 17-gauge arthroscopic needle (Smith & Nephew). By use of an arthroscopy pump (Arthrex, Naples, FL) with the pressure set at 40 to 50 mm Hg, fluid is introduced into the joint. A capsulotomy extending from the midanterior to anterolateral or posterolateral portal is performed with a banana blade (Smith & Nephew), and the anterolateral portal is used as the viewing portal whereas the midanterior portal is the working portal for the initial part of the procedure (step 3). A complete diagnostic evaluation of the hip joint, including the labrum, articular cartilage surfaces, and lunate fossae or ligamentum teres, is performed. It is not uncommon to see more cartilage destruction than expected based on hip pathomorphology due to products produced by the OO.
Table 1Step-by-Step Guide to Acetabular Osteoid Osteoma Identification and Removal
1. Position the patient supine on the table.
2. Use an image intensifier to confirm bony landmarks and assist in establishing portals.
3. Use the anterolateral portal as the viewing portal and the midanterior portal as the working portal.
4. Use a burr to unroof the rim-based lesion. Gently elevate and preserve the labrum if needed.
5. Identify hyperemic punctate tissue, confirming the correct position.
6. Use a ring curette to completely excise the body of the lesion.
7. Consider the use of an ablator to sterilize the lesion bed. Be mindful of the cartilage.
8. Repair the labrum as needed.
9. Address concomitant pathology in the peripheral compartment.
Acetabular rim lesions are readily identifiable after rim decortication using a 5.5-mm motorized burr (Smith & Nephew) (step 4) to a predetermined depth based on preoperative imaging (CT) (Fig 3A). The OO is unroofed with the burr, and punctate hyperemic fibrous tissue (step 5) will be shown within the lesion, which should be curetted with a ring curette (Smith & Nephew) (Fig 3 B and C) (step 6). Finally, an ablator (Eflex Ablator; Smith & Nephew) can be used to ablate the lesion, with the surgeon being mindful of the proximity to the articular cartilage (step 7). Adequate resection can be assessed by observing normal cancellous bone circumferentially around the initial lesion location (Fig 3D). Femoral (cam) and acetabular (pincer) pathomorphologies are treated as indicated, and the labrum is typically repaired or stabilized using suture anchors (Bioraptor; Smith & Nephew) (step 8). The anchors should be spaced every 8 to 10 mm, and 2 to 4 anchors are typically used for focal anterior or anterolateral rim resections (Fig 4A). Traction is released, and the peripheral compartment is accessed to evaluate for cam-type FAI. Femoral osteoplasty is then performed, when indicated, with a motorized 5.5-mm burr (Long Abrader Burr; Smith & Nephew) (Fig 4B, Video 1) (step 9). After FAI correction, the hip is exsanguinated of all fluid and bony debris, and the capsulotomy is closed with three to five No. 2 nonabsorbable sutures (Ultrabraid; Smith & Nephew) in a side-to-side fashion using a suture shuttle technique (70° Upbend Accu-Pass; Smith & Nephew) (step 10).
The postoperative course is typically directed by any concomitant work performed in excess of the OO excision. In the case of a concomitant labral repair and arthroscopic FAI correction, the patient is discharged from the hospital on the day of the procedure. The patient remains toe-touch weight bearing for 2 to 3 weeks, and crutches are discontinued around 3 weeks when the gait is normalized, non-antalgic, and pain free. There are no specific range-of-motion restrictions. Derotational boots, hip braces, and continuous passive motion machines are not typically used with the exception of patients with connective tissue disorders or severe hypermobility and revision procedures.
OO is a benign bone tumor associated with nocturnal pain and symptom relief with NSAIDs. It presents radiographically as a central nidus with surrounding reactive sclerotic bone. Identification of the central nidus, seen to a greater advantage on CT versus MRI,
is important to make the correct diagnosis of OO. Although symptomatic treatment with NSAIDs as part of a conservative treatment program is an option, chondral damage from the lesion may occur and might lead to early osteoarthritis.
CT-guided RFA has several distinct advantages over open surgical removal including a shorter length of hospital stay, lower cost, less traumatic access to deep locations around the pelvis and femur, and lower complication rate.
Thus, RFA is now considered the standard of care for the treatment of OO. Major pitfalls of RFA include incomplete excision of the lesion resulting in recurrence or persistent symptoms and potential destruction of the articular cartilage when treating periarticular lesions.
reported on transarticular arthroscopic removal of a juxta-articular lesion using CT guidance. Our report differs in both the location of the OO nidus and the approach for removal. In our case, by use of meticulous technique, the OO was approached and addressed with complete cartilage preservation. Addressing some of these lesions arthroscopically overcomes potential pitfalls associated with RFA. The experienced hip arthroscopist is intimately familiar with the arthroscopic anatomy and can directly visualize complete removal of the lesion while minimizing damage to the articular cartilage. Biopsy specimens can be submitted for histopathologic examination if the appearance is in question. In addition, these lesions are often associated with significant synovitis, which can also be addressed at the time of lesion removal by arthroscopic synovectomy. The comprehensive complication rates for hip arthroscopy are reported to be 0.58% and 7.5% for major and minor complications, respectively.
Reported complications and adverse events include but are not limited to neurapraxia, stress fractures and iatrogenic instability, iatrogenic articular cartilage and labral damage, fluid extravasation, and instrument breakage.
In addition, we recognize it would be exceedingly difficult to address deep-seated lesions around the pelvis with arthroscopy or endoscopy and generally accept that access is limited to the periarticular area. We recognize that each procedure is associated with unique risks and benefits; however, in this case arthroscopy appears to be well suited for the treatment of an acetabular rim–based OO. In this report we describe an arthroscopic technique to perform resection of an acetabular rim–based OO, in addition to managing associated symptomatic FAI. This technique provides the benefits of protection of the articular cartilage, minimal risk of avascular necrosis, and the ability to address concomitant pathology (Table 2). Risks of the procedure including neurapraxia, labral damage, and fluid extravasation need to be considered as well as the benefits.
Table 2Advantages and Risks of Arthroscopic Resection Versus RFA or Open Resection
Small incision vs wide exposure and possible surgical dislocation with open technique
Minimal risk of avascular necrosis vs open technique
Safe preservation and protection of cartilage vs RFA
Theoretical advantage of decreased recurrence rate because of visually confirming removal vs RFA
Ability to address concomitant pathology vs RFA
Risks and disadvantages
Possibility of neurapraxia with prolonged traction time
Iatrogenic instability with aggressive resection
Iatrogenic articular cartilage damage with non-careful instrumentation
The patient is positioned supine on the operating table (step 1), and an image intensifier is used to confirm bony landmarks and assist in establishing portals (step 2). After access to the hip joint has been gained, an interportal capsulotomy extending from the midanterior to anterolateral portal is performed with a banana blade. The anterolateral portal is used as the viewing portal whereas the midanterior portal is the working portal for the initial part of the procedure (step 3). All viewing is completed with a 70° arthroscope. A complete diagnostic evaluation of the hip joint is performed including evaluation of the labrum, articular cartilage surfaces, and lunate fossae. Bruising of the labrum due to cam impingement is identified in the lateral labrum with some labral-chondral disruption anteriorly. A shaver and ablator are used to expose the acetabular rim in preparation for rim decortication with a 5.5-mm motorized burr. The acetabular rim lesion is readily identified after rim removal to the predetermined depth as established on computed tomography evaluation (step 4). Four to 5 millimeters of resection exposes the lesion, and the surgeon must remain vigilant to avoid inadvertent cartilage destruction. The lesion shows punctate hyperemic fibrous tissue typical of an osteoid osteoma (step 5). A rim resection has also been completed on our approach to the lesion. A ring curette is used to precisely excise the lesion (step 6). Resection is continued until normal cancellous bone is present circumferentially around the initial lesion location. Finally, a thermal ablator device (Eflex Ablator) is used to ablate and sterilize the lesion, with the surgeon again being mindful of the proximity to the articular cartilage (step 7). After adequate lesion removal, anterior inferior iliac spine decompression, and rim resection, the labrum is repaired with PEEK (polyether ether ketone) suture anchors (step 8). Sutures are passed in a vertical mattress fashion with a suture passer. Appropriate suture and anchor placement avoids eversion of the labrum with anchors placed at the 10-, 11-, 12-, and 1-o'clock positions. Traction is released, and the peripheral compartment is accessed to evaluate the femoral cam lesion (step 9). A large femoral lesion is seen in this case, viewing from the midanterior portal and working through the anterolateral portal. The femoral osteoplasty is performed with a motorized 5.5-mm burr. The lesion is addressed from the medial to lateral synovial folds with careful attention paid to avoid the vessels. Dynamic evaluation subsequently shows appropriate cam resection and resolution of the area of conflict. After femoroacetabular impingement correction, the hip is exsanguinated of all fluid and bony debris (step 10). A capsular repair is completed with three to five No. 2 nonabsorbable sutures placed in a side-to-side fashion using a suture shuttle technique.
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