**4. Surgical technique**

two fingerbreadths lateral and distal of the ASIS and extends distally and posteriorly in line with the tensor fasciae latae muscle [20]. A slightly more lateral position can help to avoid the lateral femoral cutaneous nerve (LFCN) that enters the thigh medially to the ASIS (**Figure 1**). The approach uses an intermuscular plane and does not require muscle releases. Medially, the interval borders to the Sartorius muscle (innervated by the femoral nerve) and laterally to the tensor fasciae latae muscle (innervated by the superior gluteal nerve) [22]. While the original Smith-Petersen approach entered between the sartorius muscle and the tensor fasciae latae, the modern anterior approach usually stays inside the fascia of the tensor fasciae latae to minimize the risk to injure the LFCN (**Figure 2**) [22]. Care should be taken not to confuse the medial located sartorius muscle and the more lateral tensor fasciae latae. Both can usually, easily be separated by the direction of the fibers. The tensor fasciae latae muscle fibers ran toward the lateral thigh in contrast to the sartorius muscle fibers, which run medially. After skin incision, the fascia of the tensor is split followed by deep finger dissection to separate the overlying fascia and the muscle belly of the tensor fasciae latae and progress toward its

The deep intermuscular fat tissue between tensor and rectus femoris muscle contains the ascending branch of the lateral circumflex artery just proximal to the vastus lateralis muscle. At the level of the capsule, the interval is bordered by the gluteus medius (superior gluteal nerve) and medially by the rectus femoris muscle (femoral nerve). Ligations of the branches of the circumflex vessels are necessary to prevent perioperative bleeding and postoperative

A Hohmann retractor is used to expose the anterior hip capsule. It is placed underneath the rectus muscle. A second blunt retractor is placed around the lateral femoral neck. The reflected head of the rectus femoris muscle is elevated and released to expose the capsule entirely. The released tendon can be marked to facilitate its identification and repair at the

medial borders.

104 Total Hip Replacement - An Overview

hematoma formation (**Figure 3**).

**Figure 2.** Incision of the fascia of the tensor fasciae latae muscle.

end of the procedure.

The procedure is performed under general or regional anesthesia. It can be performed with a standard operating table with an Omni-Tract® femur elevating system (Integra, Plainsboro, NJ, USA) or a specialized orthopedic table (Hana®, Mizuho OSI, Union City, CA, USA). The latter helps to control hip rotation, abduction, flexion, and traction of the affected extremity and facilitates exposure of the proximal femur for femoral component insertion. However, the costs, fracture risk, and limited ability to intraoperatively test the range of motion (ROM) are its main disadvantages. A number of alternative tables are currently available by other manufactures.

The authors recommend careful templating and implant selection. The primary goal of the templating is to guide acetabular reaming toward the most appropriate reamer size. On the femoral side, depending on the type of femur, shorter implants with less sizable distal dimensions might be preferred in a Dorr Type A Femur, while compression broaching for a longer implant with a collar might be preferred for a Dorr Type C femur [23]. In addition, careful planning of the femoral neck resection can help intraoperatively to restore the leg length.

The patient is lying supine on the table with a perineal post and both legs secured with the feet in boots. The pelvis and the nonsurgical hip are placed in a neutral position. After the standard anterior approach, as described above, a T-shaped capsulotomy is performed with medial and lateral extension at the level of the intertrochanteric ridge (**Figure 4**). The capsule can be tagged and preserved for later repair. Two Hohmann retractors are now placed within the capsule around the lateral and medial femoral neck. A napkin ring double osteotomy of the femoral neck is performed to ease removal of the head (**Figure 5**). The femoral head is removed with a corkscrew extractor. Additional traction and external rotation on the operated

a short incision of the medial capsule. This is, followed by an anterior retractor, placed between the anterior labrum and capsule. A posterior retractor can be placed between the posterior labrum and capsule. The foveal tissue and labrum are removed. The acetabulum is either reamed under direct visualization or under fluoroscopy guidance. A press fit cup is placed and impacted (**Figure 6**). To facilitate cup alignment under the anterior acetabular bone, an implant less hemispherical then 180° is preferred. It also helps to medialize the center

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The C-arm is used to guide intraoperative component positioning. An alternative to this technique is the use of intraoperative navigation. Because of the supine position and easy access to the iliac crest intraoperative navigation is usually fairly straightforward in anterior THA. Other techniques available for optimized cup position are based on C-arm images and include software programs like Radlink® (Radlink, El Segundo, CA, USA) and Jointpoint®

The C-arm is positioned in 90° to the supine patient and centered over the pelvis to make sure the pelvis is in a neutral position (**Figure 7**). A neutral pelvis position is the requirement for any of the described C-arm based algorithms. If no software is available, the cup inclination can be checked with the C-arm centered in the middle of the pelvis. After reaching the target inclination of the acetabular component, the C-arm is moved over the operated hip. After estimating the cup anteversion based on the opening ellipse, the cup anteversion can be determined based on the C-arm tilt angle described by Boettner et al. and Zingg et al. [6, 24] (**Figure 8**). When aligned perfectly the elliptical shape of the cup presents as a line. The tilt angle can be measured on the C-arm and used to calculate the acetabular anteversion. Following correct acetabular

Exposure of the proximal femur can be facilitated by a standard release to minimize traction forces on the greater trochanter. This prevents intraoperative complications like fractures

implant positioning, the final liner is inserted and osteophytes are removed.

**Figure 6.** A press fit cup is placed and impacted into the reamed acetabulum.

of rotation in comparison to a hemispherical cup.

(Jointpoint Inc., Belleair Bluffs, FL, USA).

**Figure 4.** Markings for the T-shaped capsulotomy with medial and lateral extension.

**Figure 5.** Photograph of a napkin ring double osteotomy of the femoral neck.

leg supports removal of the napkin ring and exposure of the acetabulum. Alternatively, to the *in situ* neck osteotomy, the hip can be dislocated using a corkscrew. The capsular releases are completed with the hip dislocated before the hip is reduced, the neck is cut, and the head removed (technique according to Matta et al. [20]).

Multiple retractors are used to facilitate acetabular exposure. First, an acetabular retractor is placed inferiorly to the fovea against the transverse acetabular ligament. This usually requires a short incision of the medial capsule. This is, followed by an anterior retractor, placed between the anterior labrum and capsule. A posterior retractor can be placed between the posterior labrum and capsule. The foveal tissue and labrum are removed. The acetabulum is either reamed under direct visualization or under fluoroscopy guidance. A press fit cup is placed and impacted (**Figure 6**). To facilitate cup alignment under the anterior acetabular bone, an implant less hemispherical then 180° is preferred. It also helps to medialize the center of rotation in comparison to a hemispherical cup.

The C-arm is used to guide intraoperative component positioning. An alternative to this technique is the use of intraoperative navigation. Because of the supine position and easy access to the iliac crest intraoperative navigation is usually fairly straightforward in anterior THA. Other techniques available for optimized cup position are based on C-arm images and include software programs like Radlink® (Radlink, El Segundo, CA, USA) and Jointpoint® (Jointpoint Inc., Belleair Bluffs, FL, USA).

The C-arm is positioned in 90° to the supine patient and centered over the pelvis to make sure the pelvis is in a neutral position (**Figure 7**). A neutral pelvis position is the requirement for any of the described C-arm based algorithms. If no software is available, the cup inclination can be checked with the C-arm centered in the middle of the pelvis. After reaching the target inclination of the acetabular component, the C-arm is moved over the operated hip. After estimating the cup anteversion based on the opening ellipse, the cup anteversion can be determined based on the C-arm tilt angle described by Boettner et al. and Zingg et al. [6, 24] (**Figure 8**). When aligned perfectly the elliptical shape of the cup presents as a line. The tilt angle can be measured on the C-arm and used to calculate the acetabular anteversion. Following correct acetabular implant positioning, the final liner is inserted and osteophytes are removed.

Exposure of the proximal femur can be facilitated by a standard release to minimize traction forces on the greater trochanter. This prevents intraoperative complications like fractures

**Figure 6.** A press fit cup is placed and impacted into the reamed acetabulum.

leg supports removal of the napkin ring and exposure of the acetabulum. Alternatively, to the *in situ* neck osteotomy, the hip can be dislocated using a corkscrew. The capsular releases are completed with the hip dislocated before the hip is reduced, the neck is cut, and the head

Multiple retractors are used to facilitate acetabular exposure. First, an acetabular retractor is placed inferiorly to the fovea against the transverse acetabular ligament. This usually requires

removed (technique according to Matta et al. [20]).

**Figure 5.** Photograph of a napkin ring double osteotomy of the femoral neck.

**Figure 4.** Markings for the T-shaped capsulotomy with medial and lateral extension.

106 Total Hip Replacement - An Overview

however, the senior author favors the release of the conjoined tendon. The piriformis muscle insertion is preserved together with the posterior capsule, obturator externus muscle, and

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The Hana table® or Omni-tract® retractor provides a hook attached to a connector arm of the table. In combination with maximum extension of the leg, the hook elevates the femur anteriorly and provides better exposure for the preparation of the femoral component (**Figure 9**). Offset handles facilitate the broaching of the femur. Femoral preparation and broaching the femoral canal is done in a standardized fashion (**Figure 10**). The final trial stem is impacted

Care should be taken not to injure the tensor fasciae latae. Good exposure to the femoral canal eases preparation and broaching. After adding the trial neck and head, the surgeon can reduce the dislocate hip with gentle traction and internal rotation. The surgeon guides the femoral head into the socket. Fluoroscopy can be used to assess leg length discrepancy, offset,

For measurements of the leg length discrepancy, the inter-teardrop line is used as horizontal reference of the fluoroscopy image. The difference between the vertical distances from the reference line to the most prominent point on each lesser trochanter defines the leg length discrepancy with reference to the contralateral hip. Neutral pelvis position and equal leg abduction and rotation are required for accurate measurements. Alternatively, leg length and offset can be determined by overlaying two print-out images and comparing the contour of the operated hip to either the opposite normal or the preoperative image. Finally, the definite femoral component is implanted. The wound is irrigated and the anterior capsule closed using Vicryl #0 suture (**Figure 11**). The reflected head of the rectus can be repaired. Finally, the

fascia of the tensor fasciae latae muscle is closed with #0 Vicryl sutures (**Figure 12**).

**Figure 9.** A hook attached to a connector arm of the table facilitates femoral exposure.

quadratus femoris muscle.

and implant alignment.

into the femur with a trial head and neck.

**Figure 7.** C-arm position in a 90° angle to the supine patient. The beam is centered over the neutral pelvis to assess inclination of the cup.

**Figure 8.** C-arm is tilted away from the operated hip until the ellipse of the positioned acetabular component is a straight line. The tilt angle is measured on the C-arm.

during anterior mobilization of the femur. The gluteus minimus muscle is elevated of the lateral capsule. The operated leg is positioned in extension, 90° external rotation and 20° adduction. In flexible patients adequate exposure might be possible without further releases; however, the senior author favors the release of the conjoined tendon. The piriformis muscle insertion is preserved together with the posterior capsule, obturator externus muscle, and quadratus femoris muscle.

The Hana table® or Omni-tract® retractor provides a hook attached to a connector arm of the table. In combination with maximum extension of the leg, the hook elevates the femur anteriorly and provides better exposure for the preparation of the femoral component (**Figure 9**). Offset handles facilitate the broaching of the femur. Femoral preparation and broaching the femoral canal is done in a standardized fashion (**Figure 10**). The final trial stem is impacted into the femur with a trial head and neck.

Care should be taken not to injure the tensor fasciae latae. Good exposure to the femoral canal eases preparation and broaching. After adding the trial neck and head, the surgeon can reduce the dislocate hip with gentle traction and internal rotation. The surgeon guides the femoral head into the socket. Fluoroscopy can be used to assess leg length discrepancy, offset, and implant alignment.

For measurements of the leg length discrepancy, the inter-teardrop line is used as horizontal reference of the fluoroscopy image. The difference between the vertical distances from the reference line to the most prominent point on each lesser trochanter defines the leg length discrepancy with reference to the contralateral hip. Neutral pelvis position and equal leg abduction and rotation are required for accurate measurements. Alternatively, leg length and offset can be determined by overlaying two print-out images and comparing the contour of the operated hip to either the opposite normal or the preoperative image. Finally, the definite femoral component is implanted. The wound is irrigated and the anterior capsule closed using Vicryl #0 suture (**Figure 11**). The reflected head of the rectus can be repaired. Finally, the fascia of the tensor fasciae latae muscle is closed with #0 Vicryl sutures (**Figure 12**).

**Figure 9.** A hook attached to a connector arm of the table facilitates femoral exposure.

during anterior mobilization of the femur. The gluteus minimus muscle is elevated of the lateral capsule. The operated leg is positioned in extension, 90° external rotation and 20° adduction. In flexible patients adequate exposure might be possible without further releases;

**Figure 8.** C-arm is tilted away from the operated hip until the ellipse of the positioned acetabular component is a straight

**Figure 7.** C-arm position in a 90° angle to the supine patient. The beam is centered over the neutral pelvis to assess

inclination of the cup.

108 Total Hip Replacement - An Overview

line. The tilt angle is measured on the C-arm.

**Figure 10.** Photograph shows broaching of the femoral component.

**Figure 11.** Tagging sutures in the medial and lateral capsular sleeve.

Many surgeons prefer a curved "Banana Type" stem for the anterior approach. Straight stem designs with a lateral shoulder require more aggressive releases including the piriformis tendon. There have been some concerns about increased femoral loosening rates and continued efforts are made to improve and develop femoral implant design. Due to the missing lateral shoulder, the curved stem provides no lateral support. As a result, lateralization and subsidence with weight bearing can occur. The new stem designs often add a medial collar to augment primary stability for immediate weight bearing and reduced risk of subsidence (**Figure 13**).

**Figure 13.** DePuy Synthes, Warsaw, IN, USA: (A) Medial collar and triple tapered ACTIS® Total Hip System. (B) Tapered-

wedge TRI-LOCK® Bone Preservation Stem. (C) SUMMIT® Tapered Hip System.

**Figure 12.** Photograph of the closed fascia of the tensor fasciae latae. A local anesthetic is injected into the subcutaneous

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To increase short and long-term stability, fully coated stems are preferred to achieve more reliable fixation. In addition, an overall more canal filling proximal stem design provides more proximal bone fixation compared to blade shaped medial-lateral implant

fixation.

layer.

**Figure 12.** Photograph of the closed fascia of the tensor fasciae latae. A local anesthetic is injected into the subcutaneous layer.

**Figure 13.** DePuy Synthes, Warsaw, IN, USA: (A) Medial collar and triple tapered ACTIS® Total Hip System. (B) Taperedwedge TRI-LOCK® Bone Preservation Stem. (C) SUMMIT® Tapered Hip System.

with weight bearing can occur. The new stem designs often add a medial collar to augment primary stability for immediate weight bearing and reduced risk of subsidence (**Figure 13**).

Many surgeons prefer a curved "Banana Type" stem for the anterior approach. Straight stem designs with a lateral shoulder require more aggressive releases including the piriformis tendon. There have been some concerns about increased femoral loosening rates and continued efforts are made to improve and develop femoral implant design. Due to the missing lateral shoulder, the curved stem provides no lateral support. As a result, lateralization and subsidence

**Figure 10.** Photograph shows broaching of the femoral component.

110 Total Hip Replacement - An Overview

**Figure 11.** Tagging sutures in the medial and lateral capsular sleeve.

To increase short and long-term stability, fully coated stems are preferred to achieve more reliable fixation. In addition, an overall more canal filling proximal stem design provides more proximal bone fixation compared to blade shaped medial-lateral implant fixation.
