Introduction

This chapter is meant to give an accurate description of the anterolateral approach as used in minimally-invasive hip arthroplasty. This approach can be used with any short-stem system existing so far and also for normal stem implantation. A description of a minimally-invasive hip-replacing procedure using the NANOS neck preserving short-stem system (distributed by Smith and Nephew, Memphis, Tennessee, USA) is provided elsewhere in the book. Various approaches to hip replacement have been described so far, each taking advantage of special anatomical conditions and each having certain assets and drawbacks.1 Growing numbers of patients of all age-groups result in an increasing demand for reduction of hospital stay and early return to full mobility. Therefore, new approaches to and new techniques of total joint replacement have been developed and tested in the past. The term “minimally invasive surgery” (MIS) in hip replacement is yet to be defined exactly. Some surgeons relate to MIS as causing only minimal damage to anatomical structures (muscle, tendons, etc.), while others define MIS as using an incision smaller than 10 cm and to some it is the combination of both.2 The advantages of these techniques in comparison to conventional surgery can neither be found in long-term results nor in the cost-effectiveness,3 but in the postoperative recovery phase. Patients show an early return to full mobility, due to the minimal tissue damage, hence reducing time of hospital stay.4-6 Above, the cosmetic advantage, especially of interest to young patients, is evident. Thus, minimally-invasive surgeries in hip-replacement are increasingly requested by patients of all ages, even becoming a patients’ criterion of the surgeon’s standard.7

Positioning

Correct positioning of the patient is essential for a successful operation. In the anterolateral approach the patient is placed in the supine position at the edge of an operating table that allows for hyperextension of both legs. The operated leg is draped to allow unrestricted intraoperative mobility of the leg (Fig. 9.1).

Approach

Here the modified (tissue conserving) Watson-Jones approach is described, in which the skin incision is made strictly laterally above the greater trochanter, parallel to the leg axis and is continued symmetrically 3-4 cm in proximal and distal directions (Figs 9.2 and 9.3). The subcutaneous layer is divided down to the fascia lata, which is released from the fat layer

Total Hip Arthroplasty

Figure 9.1: Positioning-draping

Figure 9.2: Marking of anatomical structures and incision line

Figure 9.3: Incision of skin

Anterolateral Approach in Minimally Invasive Hip Replacement

Figure 9.4: Releasing fasica lata from subcutaneous fat layer

Figure 9.5: Fascia lata

on the cranial and the caudal sites (Figs 9.4 and 9.5) and split with a dorsal convex, arc-shaped fascial-incision (Fig. 9.6). The surgeon’s index finger is going from the distal incision over the vastus lateralis muscle and the femur into the open anatomical space over the femoral neck. A door shaped opening is created in the joint capsule, which is partially resected (Fig. 9.7). Taking advantage of the anatomically contoured gap in the muscles, one Hohmann retractor (HR) is placed on the capsule over the cranial edge of the femoral neck to retract the Gluteus Medius muscle in the cranial direction and one blunt HR is placed on the caudal end of the femoral neck. Another broad tipped HR is inserted on the ventral rim of the acetabulum (Fig. 9.8). The way of resecting the femoral head is dependent on the system being used. After resection of the femoral head (Figs 9.9 and 9.10), the HRs have to be repositioned in order to provide maximal protection to the soft tissue while reaming the acetabulum. Leaving the wide HR in place, a two-pronged HR is placed around the dorsal acetabular rim and another HR is placed above the caudal rim of the acetabulum (Fig. 9.11). In minimally-invasive approaches the reamer as well as all other instruments should always be inserted carefully in order to avoid soft tissue damage. Then the acetabulum is reamed in the way and to the degree necessitated by the planned cup (Fig. 9.12).

Total Hip Arthroplasty

Figure 9.6: Dorsal convex incision of fascia lata

Figure 9.7: Door-shaped incision and partial resection of capsule

Figure 9.8: Positioning of Hohmann retractors (HR) Cr: Hohmann retractor (HR) placed on the capsule over the cranial edge of the femoral neck

V: HR inserted on the ventral rim of the acetabulum Cd: Broad tipped HR placed on the caudal end of the femoral neck

Anterolateral Approach in Minimally Invasive Hip Replacement

Figure 9.9: Head-extractor inserted into femoral head

Figure 9.10: Femoral head removed

Figure 9.11: Acetabulum. Repositioning of Hohmann retractors (HR):

V: Wide ventral HR is left in position

D: Two-pronged HR placed around the dorsal acetabular rim

C: HR placed above the caudal rim of the acetabulum

Total Hip Arthroplasty

Figure 9.12: Reaming of acetabulum

Figures 9.13A and B: Impaction of cup

CUP-IMPLANTATION

The cup, fitted to the inserter, is then impacted into the reamed acetabulum with the desired anteversion and inclination (Figs 9.13A and B). Following, the inlay is impacted into the cup and its position is checked.

OPENING THE INTRAMEDULLARY CANAL

In order to ream the intramedullary canal of the femur and to insert the implant properly, the patient’s leg has to be positioned in the following way: both legs have to be hyperextended by 20-30°, which should be allowed for by the table being used. The knee of the operated leg has to be positioned above the knee of the hyperextended other leg. Therefore the operated leg has to be adducted, flexed by over 90° and externally rotated by 90° (Fig. 9.14). Protection of soft tissues should be provided by two HRs, one to protect the Gluteus medius muscle and another is placed over the medial femoral neck (Fig. 9.15). Depending on the system being used, different kinds of rasps (Figs 9.17A and B) are used to open up the course of the femoral neck through a central entry point (Fig. 9.16). After the medullary cavity is widened by the rasps the cancellous bone can be compacted by the use of cancellous bone impactors.

Anterolateral Approach in Minimally Invasive Hip Replacement

Figure 9.14: Positioning for implantation of femoral prosthesis

Figure 9.15: Repositioning of Hohmann retractors (HR):

D: HR to protect Gluteus medius muscle

V: HR placed over the medial femoral neck

Figure 9.16: Entry-point in femoral neck to medullary canal

Total Hip Arthroplasty

Figures 9.17A and B: (A) Small-curved rasp (B) Prosthesis-shaped rasp

Figure 9.18: Wound closure

IMPLANTATION OF PROSTHESIS

The exact steps of the subsequent procedure differ from system to system. Basically, compactors of increasing size are impacted into the femur until the planned size is reached and the compactor has contact to the cortical bone. After correct implantation of the prosthesis, confirmed by a control X-ray, the femoral head is reduced into the cup. Finally, before the wound is irrigated and closed in layers (Fig. 9.18), the range of motion as well as the absence of any impingement has to be checked as usually.

Postoperative Management

Single-shot antibiotic cover and perioperative thromboprophylaxis are recommended. General periods for soft tissue regeneration as well as osseointegration have to be considered. Regarding the soft tissue incision and the yet slight surgical trauma (Fig. 9.19), we recommend a 4-week period of partial weight-bearing on the operated leg.

Figure 9.19: Postoperative scar (scale in cm)

Cautions

Numerous publications show good results of this and other minimally-invasive approaches in intra- and postoperative aspects, but a fundamental learning curve is near to always mentioned. Therefore surgeons having only little experience with MIS should either choose a conventional approach that they are trained in to implant a new prosthetic system, or train the MIS approach with their well known system.8

Anterolateral Approach in Minimally Invasive Hip Replacement

References

1. Daniel Kelmanovich, Michael L Parks, Raj Sinha, William Macaulay. Surgical approaches to total hip arthroplasty. Journal of the Southern Orthopaedic Association 2003;12(2):90-4.

2. Sendtner E, Boluki D, Grifka [Current state of doing minimal invasive total hip replacement in Germany, the use of new implants and navigation—results of a nation-wide survey]. [Article in German] Z Orthop Unfall J 2007;145(3):297-302.

3. de Verteuil R, Imamura M, Zhu S, Glazener C, Fraser C, Munro N, et al. A systematic review of the clinical effectiveness and cost-effectiveness and economic modelling of minimal incision total hip replacement approaches in the management of arthritic disease of the hip. Health Technol Assess 2008;12(26):iii-iv, ix-223.

4. Wohlrab D, Hagel A, Hein W. [Advantages of minimal invasive total hip replacement in the early phase of rehabilitation]. [Article in German]. Z Orthop Ihre Grenzgeb 2004;142(6):685-90.

5. Berger RA, Jacobs JJ, Meneghini RM, Della Valle C, Paprosky W, Rosenberg AG. Rapid rehabilitation and recovery with minimally invasive total hip arthroplasty. Clin Orthop Relat Res 2004;429:239-47.

6. Kennon RE, Keggi MJ, Keggi KJ. [The minimally invasive anterior approach to hip arthroplasty]. [Article in German]. Orthopäde. 2006;35(7):731-7.

7. Kubes J, Landor I, Podskubka A, Majernícek M. [Total hip replacement from a MIS-AL approach (comparison with a standard anterolateral approach)]. Acta Chir Orthop Traumatol Cech 2009;76(4):288-94.

8. Röttinger H. [Minimally invasive anterolateral approach for total hip replacement (OCM technique)]. [Article in German] Oper Orthop Traumatol 2010;22(4):421-30.