Radiographic and anatomic landmarks to approach the anterior capsule in hip arthroscopy

Hip arthroscopy (HA) is considered to be a very difficult and demanding surgical procedure, special instruments, an image intensifier and a fracture table or hip distractor are required to access the hip joint, the most common and worldwide used HA technique is entering blindly to the central compartment with the use of fluoroscopy and continuous distraction; with the potential danger if performed in unskillful hands of labral penetrations, labral resections and scuffing of the femoral head cartilage. Our technique describes the arthroscopic management of femoroacetabular impingement (FAI), performing a preoperative planning using radiographic and anatomic landmarks to approach the anterior capsule without the use of fluoroscopy. Access to the hip joint is made extra-articularly from the peritrochanteric compartment palpating the greater trochanter and posteriorly penetrating the iliotibial band sliding the arthroscopic sheath and obturator from the trochanteric border to the anterior femoral neck to visualize the anterior capsule bursa and anterior capsule fibers and posteriorly following our previous landmarks perform an anterior oblique Inverted ‘T’ or ‘H’ capsulotomy with a radiofrequency wand to access the cam-type impingement and distraction is made under direct controlled arthroscopic vision. Our technique in HA aiming the anterior capsule using radiographic and anatomic landmarks is safe, reliable and reproducible in FAI with big cams, deep sockets and cases with mild arthritis where the capsule is thick, stiff and calcified.


INTRODUCTION
Hip arthroscopy (HA) is considered to be a difficult and demanding surgical procedure to perform, its strong capsule, and deep constrained anatomy makes it very difficult to view and distract, the technique most used in HA is entering blindly the central compartment (CC) with fluoroscopy and continuous distraction; this technique has the danger if performed in unskillful hands of iatrogenic complications such as labrum penetrations, labrum resections and also scuffing of the femoral head cartilage [1,2,3].
New techniques have been developed to approach the hip joint extra-articularly and without fluoroscopy, others have a starting point from the peripheral compartment (PC) first [4,5].
Our technique was developed due to the lack of appropriate material and instruments for HA at our institution, we approach the hip through the peritrochanteric compartment penetrating the iliotibial band (ITB) aiming towards the PC, sliding the arthroscopic sheath and obturator from the trochanteric border to the anterior femoral neck to visualize the anterior capsule bursa and anterior capsule fibre and posteriorly following our previous radiographic and anatomic landmarks perform an oblique anterior capsulotomy with a radiofrequency (RF) wand.
Knowledge of the hip joint anatomy is mandatory and a precise localization of the anterior capsule fibres is a must; the capsulotomy needs to be performed in an oblique direction to avoid hip instability [6]. Preoperative planning on an AP of the pelvis (Radiographic landmarks) The first line is a horizontal line traced at the tip of the greater trochanter (GT), a second horizontal line is drawn at the innominate tuberosity of the femur, these two lines need to be measured with a standard ruler (generally they measure between 4 and 6 cm/3 finger breadths), the third line, is a horizontal line traced from the anterior superior iliac spine (ASIS) towards the vertebral body, the fourth line is a vertical line that runs from de superior mid vertebral body towards the pubic rami/pubic joint, the fifth line (capsulotomy line) is an oblique line rising or exiting from the innominate tuberosity of the femur to intersect the third and fourth line, this fifth line will closely represent and mimic the femoral neck axis and it is a guide to the surgeon to perform the anterior oblique capsulotomy ( Fig. 4; Table I).

SURGICAL TECHNIQUE
Intraoperative planning on the patient's hip (Anatomic landmarks) Localize the tip of the GT and trace your first line, with three finger breadths (4-6 cm) from the GT distally trace you second line, palpate the ASIS and trace a line towards the midline on the patient's belly, this corresponds to your third line, from the umbilical scar, trace your fourth line towards the pubic symphysis, the fifth line or capsulotomy line will exit from the innominate tuberosity of the femur (where the second line is placed) and it will intersect lines 3 and 4, this line mimics the femoral neck axis (Table II).
Portals are marked in the safe zone [6], the anterior margin of the GT is palpated, a stab incision is performed and the AL or vision portal is placed, posteriorly penetrating the ITB sliding the obturator and arthroscopic sheath to the anterior region of the femoral neck between the gluteus medius and iliocapsularis muscle, the PSP is placed at the level of the second line by triangulation, we localize the bursa, fatty tissue and the anterior capsule fibers, we perform a bursectomy with a RF wand or shaver, rotations are made to observe and assure how the capsule moves when the femoral head is rotating; we proceed with the anterior oblique 'inverted T' or 'H' capsulotomy (Figs. 5 and 6) proximally from the acetabular rim (taking care not to damage labrum) to the trochanteric crest distally, capsulotomy is performed with extreme precaution and care to avoid instability, the two arms of the capsule must be as close as possible to perform a 2-3-stich closure if necessary (Fig. 7), if we encounter with a cam femoroacetabular impingement (FAI), an 'inverted T'-type capsulotomy is recommended to work only the head-neck junction, and if we encounter with a pincer FAI an 'H'-type capsulotomy will suffice to work on the acetabular rim, sutures can be placed in both arms of the capsule to act as reins using your desire technique and device (Table III).
Exchange to a 70 scope is done and distraction of the hip joint is performed with controlled arthroscopic vision (Fig. 7) where meticulous visualization and inspection of chondral-labral junction, labrum, acetabular and femoral head cartilage as well as the ligamentum teres. Finishing in the CC, we remove the traction half way to infiltrate viscosupplementation (previous suck drying of saline) and removal of all traction is done via arthroscopic direct vision (Fig. 8).

MATERIAL AND METHODS
Eighty-seven cases where included in this study, 59 right hips, 28 left hips, 46 cam-type FAI, 25 cases with mixt-type FAI, 4 with type 3 OA and mixt FAI, 4 osteonecrosis of the femoral head, 3 ligamentum teres tears (LTT) 2 hip    from the innominate tuberosity of the femur (where the second line was placed) and it will intersect lines 3 and 4. 6. Start your bursectomy with an RF wand or shaver, care must be taken to avoid bleeding. 7. The marked FIFTH LINE is a guide to mimic the femoral neck axis and to perform a pristine anterior oblique capsulotmy. a The plotted X-ray landmarks will be reproduced on the patient's operative hip. b Key steps are represented in Fig. 2. dysplasia, 1 revision HA for adhesions, 1 case of a rigid hip due to lipomeningocele, 1 case of rheumatoid arthritis with type 4 brooke heterotopic bone formation. Twelve patients with take down and labral refixation, 8 rim recessions, 85 had femoral osteochondroplasty, 4 patients with retrograde and arthroscopic guidance core decompression (CD), 1 case with removal of heterotopic bone, 3 patients with LT debridement.
Traction times (TT) were recorded, being the shortest one 18 min in a LT tear debridement case and the longest TT was 80 min in a core decompression of the femoral head (CDFH) case, patients with hip dysplasia had a 2-stitch capsular closure, 1 patient who had a labral refixation presented penis numbness for 7 weeks and 1 patient who had a HA and CDFH presented erectile dysfunction for 5 weeks, 3 patients were sent to physical therapy and started to early with hip extensions and presented intra-articular hematoma who needed extraction.
We did not encounter with infections, nor hip instability.

DISCUSSION
Hip Preservation surgery and HA is a popular surgical procedure nowadays because of its excellent results, the knowledge of FAI is now being international thanks to worldwide meetings, cadaver labs and master courses, but the concern and worry of HA being performed by an undertrained surgeon with unskillful hands is major, due to the fact that the procedure itself is demanding, the use of fluoroscopy is needed to avoid devastating iatrogenic complications, so knowing the anatomy of the hip joint is an extremely important factor.   Thaunat et al. [7] mention that less force of traction is applied when the capsulotomy is done prior distraction and also that distraction is made only for accessing the CC or acetabular fossa, their results demonstrated that soft tissue injuries and nerve dysfunction are extremely rare, Doron et al. [8] describe an extracapsular technique for the non-distractable hip, but they still use fluoroscopy to establish the AL portal and also they perform a trial of distraction previous the capsulotomy is done.
With this technique, like the other published extracapsular ones, we have encounter with less iatrogenic complications such as scuffing of the femoral head, labral penetrations and resections, the risk of radiation to the patient, the theatre staff and the surgeon is cero or extremely low (first 3 cases when starting the technique) [9].
We believe that our technique performed with radiographic preoperative landmarks will mimic as close as possible the femoral neck axis, which is a guide to perform a pristine anterior oblique capsulotomy to permit a more natural capsule closure (longitudinal capsule fibres) in patients who do not need capsule closure, in patients with generalized ligamentous laxity the two arms of the capsule must be as close as possible to perform a 2-3-stitch closure, we strongly believe that this technique is surgeon  friendly, very easy to perform, master, teach and there is no need for special cannulated obturators, guide wires or fluoroscopy.
Our technique in HA aiming the anterior capsule using radiographic and anatomic landmarks is safe, reliable and reproducible in FAI with big cams, deep sockets and cases with mild arthritis where the capsule is thick, stiff and calcified.