The question „Where is the incision in minimally invasive anterior hip access?“ is at the center of modern hip arthroplasty. For many patients who have to undergo hip replacement, it is crucial to know how the minimally invasive access is done anatomically, where exactly the skin is cut and what advantages this modern surgical approach offers – especially compared to classical procedures.

In this comprehensive guide, we explain to you in detail:

• What does "minimally invasive" really mean in hip surgery
• The two established approaches AMIS and ALMIS
• Where the incision is made, anatomical orientation, and practical significance
• Why the anterior-lateral area is chosen more frequently today
• Why the muscle gap under the skin is crucial
• And why treatment by a hip specialist like Prof. Dr. Kutzner at Endoprotheticum Rhein-Main in Mainz is useful
• 
  

What does "minimally invasive" mean in hip access?

A minimally invasive approach means:
The surgeon chooses a path with a small incision and minimal tissue trauma to implant the artificial hip joint. In doing so:

• the soft tissue is treated gently
• Muscle and nerve tissue not cut, but held aside
• the operation duration and postoperative pain are reduced
• the rehabilitation is accelerated

The goal is a smaller incision, less postoperative pain, and faster patient mobilization compared to traditional approaches with large skin incisions and extensive muscle damage. The minimally invasive approaches AMIS and ALMIS are leading techniques in this field.

The AMIS approach – „anterior minimally invasive approach“

What is AMIS?

The term AMIS stands for Anterior Minimally Invasive Surgery – in German: anterior minimally invasive approach to the hip joint.

The concept:

• The operation is performed from the front ("anterior") on the hip joint
• The incision is relatively small – typically about 8–12 cm long
• The muscles and tendons are not severed, but merely pushed aside
• Surgery is performed through a natural muscle gap , the so-called Hueter interval – between the tensor fasciae latae muscle (TFL) and the rectus femoris muscle or Sartorius.

Where is the incision in the AMIS access?

The incision for the AMIS approach is made front-laterally over the hip region – i.e. on the front side of the thigh, in the area between the groin and the lateral hip bone. It runs over the muscle groups, but not through them, so that the underlying muscles are spared.

Why this is important:

• Through this incision, the hip joint can be safely accessed, without severing muscles
• The natural gap between the muscles is used anatomically
• This results in less tissue trauma
• The patient can be mobilized more quickly
• Pain is often less severe than with classical approaches
• The hospital stay is often shorter

This gentle incision is a central advantage of the AMIS method compared to conventional techniques.

How does the access proceed anatomically?

Anatomically, the AMIS approach uses a muscle-sparing plane:

• Lateral: Musculus tensor fasciae latae
• Medial: Rectus femoris muscle or Sartorius muscle
• No muscle transection, but only retraction medially and laterally
• This exposes the joint and implants the prosthesis

This intermuscular and internervous approach significantly reduces injuries to muscle and nerve tissue.

Why is a cut in the anterior-lateral area more common today?

In modern hip arthroplasty, the trend has clearly developed towards anterior or anterolateral approaches – especially in minimally invasive operations like AMIS and ALMIS.

Anatomical advantages

• The musculature at the front and side is thinner and easier to shift than, for example, the strong musculature in the rear area
• By using existing muscle gaps less tissue is damaged
• More important stability muscles (abductors) can be spared
• The nerves and vessels are located in this area in such a way that they are less endangered with correct technique
• The natural gap and internervous plane allows for direct access without cutting through muscle bellies

Practical advantages

• Less postoperative pain
• Faster mobilization
• Lower risk of gait disorders such as permanent limping
• Small scar due to minimal incision
• Faster return to daily activities

It is important to understand: The skin incision is only the external entry point. The crucial factor for the gentle effect of minimally invasive approaches is the choice of the muscle and tissue layer under the skin – namely the natural muscle gap, through which the access is guided. This maximally spares muscles and tendons, and the hip joint can be safely accessed.

Why a direct incision over the groin in anterior hip access has disadvantages

While the anterior minimally invasive approach (AMIS) is generally characterized by muscle preservation and rapid rehabilitation, it has become apparent in recent years that a skin incision placed too far anteriorly – directly over the inguinal fold – has several relevant disadvantages. These experiences have led many specialized hip surgeons to prefer the anterolateral approach , where the incision is located slightly more laterally, but the anterior muscular interval continues to be utilized.



Increased risk of nerve damage to the lateral femoral cutaneous nerve

An incision very far anterior, close to the groin, often leads to immediate proximity to the lateral femoral cutaneous nerve (N. CFFL). This sensitive cutaneous nerve runs in the area of the anterior superior iliac spine (SIAS) and spreads from there in a fan shape over the upper outer thigh.

With a purely anterior, very medial approach, it can therefore lead to:

• mechanical irritation
• Overstretching
• Compression by retractors
• or even direct injury

of the lateral femoral cutaneous nerve occur.

The consequences are often stressful for patients:

• Numbness in the area of the anterolateral thigh
• Paresthesias (tingling, burning, ants crawling)
• Neuropathic pain that can persist for months or even permanently

Particularly in early AMIS-like techniques, where the incision was made very far forward at the inguinal ligament, significantly higher rates of these nerve damage were described.

Through the currently preferred anterolateral incision , the endangered nerve is significantly better protected, as the surgical approach proceeds slightly more laterally and safely circumvents the critical nerve zone at the SIAS.

Hygienic disadvantages in robust or obese patients

A central, often underestimated factor is the anatomical situation in the inguinal fold. An incision directly over the groin is located:

• in a warm skin area
• with natural moisture
• with high bacterial colonization
• and in many people in a deep skin fold, which is difficult to clean

In patients with obesity , this problem is significantly exacerbated:

• The inguinal fold is deeper, the skin overlaps more strongly
• A humid, poorly ventilated environment develops
• The wound area is difficult to access
• Dressing changes are more complicated
• The risk of wound healing disorders, maceration and superficial infections increases significantly

Therefore, clinical experience and current surgical trends clearly show:
The anterior incision, located directly above the groin, is often unfavorable in robust and obese patients and associated with higher complication rates.

Why the anterior-lateral incision has become established today

For these reasons, many specialized hip surgeons – including Prof. Dr. Kutzner – now prefer a modified, laterally offset incision, which:

• further away from the inguinal fold lies
• clearly better hygiene enabled
• the lateral femoral cutaneous nerve is more safely spared
• but continues to use the true anterior approach via the natural muscle gap (Hueter interval) under the skin

This means:
The surgical approach remains minimally invasive and muscle-sparing, but the skin incision is intelligently relocated to reduce risks.

How important is the experience of the surgeon?

Very important! Minimally invasive surgical techniques such as AMIS and ALMIS require specific training, experience and very good anatomical knowledge. The reason:

• The incision is small, so the view is more limited than with large approaches
• Orientation in the muscle-sparing planes requires high precision
• The correct placement of the implant despite the small opening is technically demanding

Therefore, the choice of a specialized hip surgeon is one of the most important factors for an optimal result.

Recommendation: Hip specialist like Prof. Dr. Kutzner at Endoprotheticum Rhein-Main

When it comes to minimally invasive hip arthroplasty with AMIS or ALMIS , the experience of the surgeon is crucial for safety and quality of outcome.

🔹 Prof. Dr. med. Karl Philipp Kutzner at Endoprotheticum Rhein-Main in Mainz is one of the leading experts in hip arthroplasty.
🔹 He has extensive experience with minimally invasive approaches such as AMIS and ALMIS and combines modern surgical techniques with individualized patient care.