ARTHROSCOPIC TREATMENT OF FAI: TECHNIQUE DESCRIPTION

ARTHROSCOPIC TREATMENT OF FEMOROACETABULAR IMPINGEMENT: A DESCRIPTION OF THE TECHNIQUE Orthopaedics, Vol 3, 2010 Alexandros P. Tzaveas Interbalkan Medical Centre

Abstract

Femoroacetabular impingement is a recently-recognized pathological entity and causes chronic hip pain in young and active patients. Hip arthroscopy, as a minimally invasive technique, became the method of choice for treatment of this condition. In this article there is a description of the arthroscopic technique for excision of impingement lesion with the patient in lateral position, and contains all the technical details and practical tips. Keywords: hip arthroscopy, femoroacetabular impingement, hip pain Introduction Femoroacetabular impingement (FAI) was described a long time ago, specifically in 1936 by Smith-Petersen (Smith-Petersen 1936). However, it has only recently been recognised as a cause of early osteoarthritis of the hip (Ganz et al 2003, Ito et al 2001). The mechanism of the condition is the repeated abutment of the proximal femur against the anterior acetabular rim, which leads to damage to the labrum and to the adjacent articular cartilage of the acetabulum (Tzaveas and Villar 2009). The aim of excising the impingement lesion is twofold: immediate relief of pain and, in the long term, prevention of osteoarthritis. Femoroacetabular impingement was initially treated with open surgery, with surgical dislocation of the hip and trochanteric osteotomy, and had promising medium-term results (Ganz et al 2001, Beck et al 2004). The high incidence of femoroacetabular impingement in young and physically active adults, as well as in elite professional athletes, has made the minimally invasive technique more attractive, since it allows a shorter period of rehabilitation and a faster return of the athlete to their activities. Preoperative assessment The history and the clinical examination are the main guides to patient selection. The impingement sign is perhaps the strongest diagnostic indicator of femoroacetabular impingement. At the same time, other intra- and extra-articular causes of pain must be excluded. The standard radiological examination includes anteroposterior and lateral radiographs of the hip, on which the alpha angle (Notzli et al 2002) and the cross-over sign (Reynolds et al 1999) are measured. MRI is always useful not only for assessing the labrum but also for excluding avascular necrosis of the femoral head. Arthroscopic treatment of femoroacetabular impingement General anaesthesia is preferred in all patients. The patient may be positioned supine or in the lateral position, according to the surgeon's preference. The author's preference is the lateral position, as described by Glick and colleagues (Glick et al 1987). Positioning of the patient is of great importance, not only in order to avoid complications but also to make the surgeon's manoeuvres easier during the operation. Traction of the hip is applied using either the Smith and Nephew traction system (Smith and Nephew Hip Positioning Device - Smith & Nephew Inc., Endoscopy Division, Andover, Massachusetts) or the McCarthy traction system (McCarthy Hip Distractor - Innomed Inc., Savannah, Georgia, USA). Particular care is taken to avoid potential injuries when positioning the patient (Fig. 1). The perineum and the genitals must be protected when the traction system is applied. Special pads are placed over these areas, but any folds in the pads must be smoothed out to avoid pressure sores. Trapping of the testicles or of the labia majora against the post of the traction system is not an uncommon hazard. It is also advisable to check carefully that the patient's body is not in contact with the metal parts of the traction system, and that the adhesive diathermy earthing pad is correctly placed on the opposite limb. Adequate space must be left between the post of the traction device and the opposite lower limb in order to avoid pressure ischaemia: a practical way of checking that the space is sufficient is for the surgeon's hand to pass easily between the opposite thigh and the post of the traction device. The foot of the affected limb must be securely immobilised in the special boot of the traction device, so that it remains tightly attached to it while traction is applied. The layout of the operating theatre is shown in Figure 2. The surgeon must be able to see both the arthroscope monitor and the image intensifier monitor at the same time. The image intensifier is positioned obliquely, leaving adequate room for the surgeon, who stands behind the patient. The layout of the surgical instruments on the two trolleys is shown in Figure 3. The deeply placed hip joint, surrounded by thick layers of soft tissue, requires special instruments for the arthroscopic technique. Extra-long instruments have therefore been designed, angled instruments are introduced through slotted cannulae, special burrs have been modified, and arthroscopic probes can be bent at various angles in order to reach areas that were once thought inaccessible. The use of a 70-degree arthroscope is recommended for both the central and the peripheral compartment. A 30-degree arthroscope may occasionally be used. The whole technique is carried out under fluoroscopic guidance. A transparent adhesive drape is used (shower-type drape - Steri-Drape Ioban 2, Large Isolation Drape with Ioban 2 Incise Film and Pouch, 3M Health Care, St. Paul, MN, USA). A fluid pump is also used throughout the arthroscopy (Fluid Management System Control Unit, Dyonics 25, Smith and Nephew, Inc, Andover, MA, USA). Finally, the use of 1 mg of adrenaline in every 3 litres of normal saline is recommended in order to reduce the likelihood of bleeding. Technique Before the instruments are introduced into the joint, it must be confirmed with the image intensifier that the joint can be distracted. Before the surgeon scrubs, traction is applied while the abductors are palpated at their insertion on the greater trochanter, until the vacuum sign appears (Griffin 1999) (Fig. 4), which indicates the negative intra-articular pressure. If the vacuum sign does not appear, the position of the patient and the correct placement of the foot in the boot are checked again in order to exclude any slackness, and traction is then applied again. Once the vacuum sign has appeared, traction is released in order to reduce its total duration, and while the surgeon is scrubbing the nurse can prepare the patient and the operative field. When the whole set-up is ready, traction is applied again. In cases with a joint effusion, capsulitis or degenerative disease, the vacuum sign may not appear at all. If this happens, it is better to introduce a needle into the joint, which on its own can create the «vacuum sign». A long needle (18 G – 1.2 mm x 205 mm) is then introduced into the hip in the supra-trochanteric area (Fig. 5), under fluoroscopic guidance, and the trocar is removed. A characteristic sound is occasionally heard as air passes into the joint and the hip distends, while an air arthrogram appears on the image intensifier screen. Then 20 to 40 ml of normal saline is injected into the joint, causing further distension of the joint. Disappearance of the air arthrogram confirms that the saline has entered the joint, and a new image will show the widening of the joint space. The first needle is then removed and two shorter needles (17G - 1.4 mm x 45 mm) are introduced anterior and posterior to the entry point of the previous needle, creating the first two portals for the central compartment (Fig. 5). Care is needed at this point to avoid puncturing the labrum: it is recommended that the needles be introduced more distally and directed upwards. It is also recommended that the needle be introduced through the «white» area formed by the air arthrogram, and not higher (Fig. 4). Puncturing the labrum gives a feeling of increased resistance as the needles are introduced, whereas puncturing the joint capsule is smoother. The posterior para-trochanteric portal is used for introducing the arthroscope, and the anterolateral portal for the arthroscopic instruments. A common pitfall for arthroscopists who are inexperienced in the hip is placing these two portals too close together: a distance of 4 to 5 cm between the portals is adequate. Triangulation of these needles can present difficulties. The position of the posterior para-trochanteric needle is important, since its direction will dictate the subsequent path of the arthroscope. For the anterolateral portal, some surgeons may choose to use the arthroscopic targeting device. A long, blunt-tipped, flexible guidewire is then passed through the posterior needle, and the needle is then removed. A small incision is then made with a scalpel around the base of the guidewire and a 4.5 mm cannulated trocar is passed over the guidewire with gentle pressure and rotating movements. Withdrawing the guidewire by a few mm before the trocar is introduced is helpful and may prevent it breaking. Once the joint has been entered, the trocar and the guidewire are removed and a 70-degree arthroscope is introduced. The anterior needle can then be seen inside the joint, so that its position can be adjusted correctly. When the anterior needle has been placed correctly, a wide capsulotomy is performed joining the two portals, using an arthroscopic knife and arthroscopic diathermy. The surgeon should then carry out a systematic examination of the central compartment, inspecting the labrum, the articular cartilage of the acetabulum, the acetabular fossa, the ligamentum teres, the anterior and posterior stellate crease, the transverse ligament and the central part of the femoral head. The arthroscopic findings should always be compared with those of the MRI of the hip, since it is not uncommon for there to be a discrepancy between the two, or for possible anatomical variants to be interpreted as pathological on MRI (Tzaveas and Villar 2010). Labral tears are treated by partial excision or repair, depending on the configuration of the lesion. Direct repair of the labrum, when indicated, is carried out with special arthroscopic sutures (FasT-Fix Suture System, Smith and Nephew, Inc., Andover, MA, USA). Reattachment of the labrum is carried out using a Bioraptor anchor (Bioraptor, Smith & Nephew Endoscopy, Andover, MA). Chondral lesions are treated with the microfracture technique. In cases of a labral tear combined with delamination of the articular cartilage, or of isolated delamination of the articular cartilage, the microfracture technique may be used together with fibrin glue (Tzaveas and Villar 2010) (Tisseel Kit, Baxter Healthcare Ltd, Norfolk, UK) in order to reattach the articular cartilage to the subchondral bone. Occasionally the ligamentum teres is shrunk with arthroscopic diathermy in cases of a partial tear. In cases of pincer-type femoroacetabular impingement the aim is to remove the ossified labrum or the prominent acetabular rim beneath the labrum, performing an acetabuloplasty (Fig. 6) while at the same time preserving the attachment of the labrum to the acetabular margin. This technique is performed in the central compartment. The surgeon tries to obtain a view of the area anterior to the anterior labrum. Using diathermy, all the soft tissue adjacent to the anterior labrum is removed, developing a sulcus between the labrum and the joint capsule. The bony acetabular rim lies at the floor of this area. Particular care is needed at this point to avoid damaging the labrum. Once the bony acetabular rim has been identified, a 4 mm arthroscopic burr (DYONICS POWER, abrader burr, Smith and Nephew, Inc. Andover, MA, USA) is used to carry out the acetabuloplasty. At this point the use of the image intensifier is essential in order to check the area of the acetabuloplasty (Fig. 7). If the labrum is damaged at this stage, it can be reattached to the bony acetabular rim with bone anchors (Khanduja and Villar 2006). When all the procedures in the central compartment have been completed, all the instruments are removed, traction is released and the hip is brought into 30 degrees of flexion. A 17-G needle is used to enter the peripheral compartment; its entry point lies proximal to the first two portals, forming an isosceles triangle with them (Fig. 5). The needle is aimed towards the head–neck junction of the femur with the help of the image intensifier. When the tip of the needle touches this area, its direction is changed to aim more anteriorly. The trocar is then removed and the return of normal saline from the cannula confirms the correct position within the anterior peripheral compartment. Sometimes the needle may enter the posterior peripheral compartment by mistake. Once the anterior peripheral compartment has been entered, the arthroscope is introduced through this portal. In order to introduce the instruments, a 17-G needle is placed through the first anterolateral portal and the image intensifier is used for correct triangulation. In effect, the tip of the second needle should meet the tip of the arthroscope on the image intensifier screen. When this is achieved the second portal is complete, and any arthroscopic instrument can be introduced into the peripheral compartment through it. These portals, which can be interchanged according to the needs of the operation, give good access to the femoral head–neck junction, the non-weight-bearing area of the femoral head, the anterior capsule, the medial synovial fold and the zona orbicularis of the capsule. After a systematic inspection of the whole peripheral compartment, an assistant flexes and rotates the joint in order to confirm the presence of the femoroacetabular impingement, and the limb is then returned to 30 degrees of flexion. It is of great importance to perform a further capsulotomy at this point, as well as to divide the zona orbicularis of the capsule. The latter can restrict the movement of the instruments considerably. The next step is to outline the true boundaries of the impingement lesion with a 90-degree arthroscopic diathermy probe (VULCAN SAPHYRE II, bipolar ablation probe – suction, Smith and Nephew, Inc. Andover, MA, USA), which strips the bony prominences of all soft tissue. A 4.0 mm arthroscopic burr (DYONICS POWER, abrader burr, Smith and Nephew, Inc. Andover, MA, USA) is then used to remove the impingement lesion. A burr of larger diameter (about 5.0 mm) may sometimes be used, although it occasionally creates a considerable amount of debris that can obscure the view. The depth of bone resection should usually be at least 5 mm, using the arthroscopic burr as a reference for comparison. The resection should continue (Fig. 8) until there is no evidence of impingement on movement of the hip. Distally, the depth of the resection should reach the same level as the anterior cortex of the femur. Diathermy is then used to achieve haemostasis in the area where bone has been removed. When the procedure comes to an end, the joint is thoroughly washed out, and local anaesthetic or hyaluronic acid, or both, may be injected once as much of the normal saline as possible has been removed from it. The skin portals are closed with nylon suture and sterile dressings are applied. Preoperatively, all patients are informed that there is a 5% chance that their symptoms will be worse after the operation, and also a small chance that it will not be possible to enter the joint. Postoperative rehabilitation All patients are informed of the long period of rehabilitation that follows the operation, which ranges between three and four months. Touch weight bearing is recommended for the first four weeks, using axillary crutches. Flexion beyond 90 degrees and excessive rotational movements are not allowed. The contribution of physiotherapy is of the greatest importance, and patients should attend one to two physiotherapy sessions a week, depending on their general progress. Isometric exercises, core exercises and swimming are allowed in the first six weeks postoperatively. Range-of-motion exercises, the static bicycle and the cross-trainer are recommended for the period between six and 12 weeks. High-impact exercises are not recommended before three months have elapsed. Results A relatively recent study (Bardakos et al 2008) assessed the outcome of femoral osteoplasty. Two groups of patients were included: the study group, which consisted of 24 patients (24 hips) with a cam-type femoroacetabular impingement lesion that was excised, and a control group of 47 patients (47 hips) who underwent hip arthroscopy but in whom the lesion was not excised. In both groups the presence of the impingement lesion was confirmed on the preoperative plain radiographs. One year postoperatively a significant improvement was seen in the modified Harris Hip Score in the osteoplasty group. The conclusion was that excision of the impingement lesion offers additional improvement in symptoms. The peripheral compartment should therefore not be overlooked during hip arthroscopy. Conclusions For more than two decades the lateral position of the patient in hip arthroscopy has been used extensively and has proved very useful. Access to both the central and the peripheral compartment can be achieved easily by the experienced arthroscopist, allowing inspection of all the anatomical structures. A wide range of techniques can be carried out, the image intensifier can be used easily, and in addition the instruments stay in the operative field when the surgeon takes his hands off them. The supine position can, however, also be used for a successful hip arthroscopy, and this comes down to the surgeon's preference. References 1. Bardakos NV, Vacsoncelos JC, Villar RN. Early outcome of hip arthroscopy for femoroacetabular impingement: the role of femoral osteoplasty in symptomatic improvement. J Bone Joint Surg Br 2008 Dec;90(12):1570-5 2. Beck M, Leunig M, Parvizi J, Boutier V, Wyss D, Ganz R. Anterior femoroacetabular impingement: part II. Midterm results of surgical treatment. Clin Orthop Relat Res 2004;418:67–73 3. Ganz R, Gill TJ, Gautier E, Ganz K, Krügel N, Berlemann U. Surgical dislocation of the adult hip a technique with full access to the femoral head and acetabulum without the risk of avascular necrosis. J Bone Joint Surg Br 2001;83:1119–1124 4. Ganz R, Parvizi J, Beck M, Leunig M, Nötzli H, Siebenrock KA. Femoroacetabular impingement: a cause for osteoarthritis of the hip. Clin Orthop Relat Res 2003:112-20 5. Glick JM, Sampson TG, Gordon RB, Behr JT, Schmidt E. Hip arthroscopy by the lateral approach. Arthroscopy 1987;3:4–12 6. Griffin DR, Villar RN. Complications of arthroscopy of the hip. J Bone Joint Surg Br 1999;81: 604-6 7. Ito K, Minka MA, 2nd, Leunig M, Werlen S, Ganz R. Femoroacetabular impingement and the cam-effect. A MRI-based quantitative anatomical study of the femoral head-neck offset. J Bone Joint Surg Br 2001;83:171-6 8. Khanduja V, Villar RN. Arthroscopic surgery of the hip: current concepts and recent advances. J Bone Joint Surg Br 2006;88: 1557-66 9. Notzli HP, Wyss TF, Stoecklin CH, Schmid MR, Treiber K, Hodler J. The contour of the femoral head-neck junction as a predictor for the risk of anterior impingement. J Bone Joint Surg Br 2002;84:556-560 10. Reynolds D, Lucas J, Klaue K. Retroversion of the acetabulum: a cause of hip pain. J Bone Joint Surg Br 1999;81:281-288 11. Smith-Petersen MN. Treatment of malum coxae senilis, old slipped upper femoral epiphysis, intrapelvic protrusion of the acetabulum, and coxa plana, by means of acetabuloplasty. J Bone Joint Surg Am 1936; 18: 869 – 880 12. Tzaveas A, Villar R. Arthroscopic treatment of femoroacetabular impingement. Br J Hosp Med (Lond). 2009 Feb;70(2):84-8 13. Tzaveas AP, Villar RN. Arthroscopic repair of acetabular chondral delamination with fibrin adhesive. Hip Int. 2010 Jan-Mar;20(1):115-9 14. Tzaveas AP, Villar RN. Cyst-like lesion of the acetabular roof - an abnormal finding or an anatomical variant? Hip Int. 2010 Apr-Jun;20(2):258-60 Figures Figure 1: The lateral position with the Smith and Nephew Hip Positioning Device. (1): the perineal post covered with special pads. (2): the secure contact of the foot inside the boot. (3): the vectors show the direction of «lateralisation» and of traction (red arrows) and of the resultant force (blue arrow). (4): adequate space has been left to prevent pressure on the opposite lower limb. Figure 2: The layout in the operating theatre for arthroscopy of the right hip, ΑΣ: patient, A: anaesthetist, Χ: surgeon, Β: assistant, Ε: scrub nurse, T1: instrument table 1, T2: instrument table 2, ΟΑ: arthroscope monitor, ΟΑΜ: image intensifier monitor, ΑΜ: image intensifier (C-arm), ΒΑ: radiographer. Figure 3: General layout of the surgical instruments on table 1(α) and 2 (β) before the operation begins. Figure 4: The complete sequence of image intensifier views during introduction of the needles and creation of the portals. 1: the vacuum sign above the femoral head after traction has been applied, 2: introduction of the first needle (18-G), 3: the introduction of normal saline eliminates the white area, 4: 40 ml of normal saline is injected, the joint has been distended and a small white area remains that shows the inferolateral part of the labrum, 5: a 17-G needle is introduced into the joint close to the femoral head so that damage to the labrum is avoided, 6: the 17-G needle has been placed successfully, 7: introduction of the second needle, 8: the second 17-G needle has been placed successfully, 9: a blunt guidewire has been passed through the cannula of the first 17-G needle, the cannula is removed and a 4.5 mm cannulated trocar is then introduced over the guidewire, 10: the guidewire is pulled slightly outwards in order to avoid it breaking as it strikes the roof of the acetabulum during introduction of the trocar, 11: the trocar is pushed into the joint, 12: the trocar has been removed and the arthroscope has been introduced through the cannula. Figure 5: A representation of the portals. ΜΤ: greater trochanter, 1: the supra-trochanteric portal for introducing the first needle and injecting normal saline, 2: the posterior para-trochanteric portal (central compartment), 3: the anterolateral portal for introducing the arthroscopic instruments (central and peripheral compartment), 4: the portal used for the camera (peripheral compartment), which forms an isosceles triangle with the other two. Figure 6. 1: the formation of the perilabral sulcus with the arthroscopic diathermy, 2: the bony acetabular rim has been exposed, 3: after the acetabuloplasty with the arthroscopic burr, 4: the pincer lesion has been removed (ΕΧ: labrum, ΑΔ: arthroscopic diathermy, ΑΕΧ: the perilabral sulcus, ΑΘ: joint capsule, ΟΔΚ: bony acetabular rim) Figure 7: The pincer lesion. (α): the position of the instruments has been confirmed with the help of the image intensifier, (β): the acetabuloplasty in progress. Figure 8. (α) the cam-type lesion (ΜΚ: femoral head, ΣΚΑ: the head - neck junction). The black curved line shows the «bump», otherwise known as the femoral prominence (β) After excision of the lesion with the arthroscopic burr (ΜΚ: femoral head, ΣΚΑ: head - neck junction).

ARTHROSCOPIC TREATMENT OF FEMOROACETABULAR IMPINGEMENT: A DESCRIPTION OF THE TECHNIQUE

Summary

Abstract

Abstract

Frequently Asked Questions

Related Services

Hip Arthroscopy

Total Hip Arthroplasty

Total Knee Arthroplasty

Dr Alexandros Tzaveas