The applied anatomy of anterior approach for minimally invasive hip joint surgery

[Total Hip Arthroplasty Using the AMIS Method: Surgical Technique, Suitability of This Method for Obese Patients, Evaluation of the Study Population]

PURPOSE OF THE STUDY

This manuscript aims to introduce our surgical technique, with an emphasis on the latest recommendations. The AMIS technique is discussed in more detail in patients with Class II and Class III obesity. We seek to prove the premise claiming that the anteversion and inclination values observed in this group of patients do not differ signifi cantly from those observed in patients with the recommended BMI index. We will also compare the risk of neurovascular bundle injury and postoperative complication rate regarding the surgical wound.

MATERIAL AND METHODS

Patients who underwent surgery using the AMIS method in the period between 1/2020 and 4/2023 were assessed retrospectively. The study included 1150 implantations. The entire study population was assessed for neurovascular bundle injury and surgical wound healing complications. For this purpose, the patients were divided into two groups based on the BMI, namely BMI < 35 kg/m2 (n=1042) and BMI > 35 kg/m2 (n=108). In patients with the BMI ≤ 25 kg/m2 (n=280) and BMI ≥ 35 kg/m2 (n=108), the inclination and anteversion values were compared. Standard centered AP view X-rays of their operated joints were assessed. The Liaw's method was used to calculate the anteversion and inclination.

RESULTS

In group one of patients with BMI ≤ 25 kg/m2 (208 women and 72 men), the arithmetic mean of acetabular anteversion was 25.4° (median 25°) and inclination was 38.3° (median 38°). In group two, which consisted of patients with BMI ≥ 35 kg/m2 (59 women and 49 men), the total arithmetic mean of acetabular anteversion was 25.1° (median 25) and inclination was 37.6° (median 37.5°). The anteversion and inclination were assessed using the Mann-Whitney test for equality of medians. The value of 0.05 was chosen as the level of signifi cance. The resulting p-value was 0.5359 in anteversion and 0.3763 in inclination. Since the p-value of both anteversion and inclination was greater than the chosen level of signifi cance, their medians have not been confi rmed to differ signifi cantly. A total of 6 cases of femoral nerve injury was reported, i.e. 0.5% out of 1150. Therefore, the risk of injury was 0.4% in the group with BMI < 35 kg/m2 (n=1042). On the contrary, in the group of patients with BMI > 35 kg/m2 (n=108), the risk was 2%. No injury to femoral artery was reported. The surgical wound healing complications were seen in a total of 87 cases (7.6%). In the group with BMI < 35 kg/m2 , healing complications of the surgical wound were observed in 7.4% of cases, with the need for revision surgery in 7 patients. In the group with BMI > 35 kg/ m2 , healing complications occurred in 13% of patients and wound revision was necessary in 4 cases.

DISCUSSION

Our results are consistent with those in the published studies that also show no signifi cant difference in anteversion and inclination of components in the compared groups of obese patients. We also agree with the other authors that the rate of complications regarding surgical wound healing is higher in these patients. The risk of neurovascular bundle injury in this study population is not higher than the standard.

CONCLUSIONS

The results obtained in our study population show that this method can also be used in patients with higher BMI, with no concern about the implantation of components in malposition or a higher risk of neurovascular injury. Nonetheless, potentially higher risk of surgical wound healing should be considered when this approach is opted for. With the appropriate surgical technique, AMIS is a safe method and, in our view, the fi rst choice especially for obese patients.

KEY WORDS

AMIS, anteversion, inclination, hip joint, obesity, BMI, implantation, total joint replacement.

What Is the Risk Posed to the Lateral Femoral Cutaneous Nerve During the Use of the Anterior Portal of Supine Hip Arthroscopy and the Minimally Invasive Anterior Approach for Total Hip Arthroplasty?

PURPOSE

To determine: (1) What is the proximity of the lateral femoral cutaneous nerve (LFCN) to the anterior portal (AP) used in supine hip arthroscopy? (2) What is the proximity of the LCFN to the incision in the minimally invasive anterior approach (MIAA) for total hip arthroplasty? (3) What effect does lateralizing the AP have on the likelihood of nerve injury? (4) What branching patterns are observable in the LFCN?

METHODS

Forty-five hemipelves were dissected. The LFCN was identified and its path dissected. The positions of the nerve in relation to the AP and the MIAA incision were measured.

RESULTS

The AP intersected with 38% of nerves. In the remainder, the LFCN was located 5.7 ± 4.5 mm from the portal's edge. In addition, 44% of nerves crossed the incision of the MIAA. Of those that did not, the average minimum distance from the incision was 14.4 ± 7.0 mm. We found a significant reduction in risk if the AP is moved medially by 5 mm or laterally by 15 mm (P = .0054 and P = .0002). The LFCN showed considerable variation with 4 branching variants.

CONCLUSIONS

These results show that the LFCN is at high risk during supine hip arthroscopy and the MIAA, emphasizing the need for meticulous dissection. We suggest that relocation of the AP 5 mm medially or 15 mm laterally will reduce the risk to the LFCN.

CLINICAL RELEVANCE

These findings should aid surgeons in minimizing the risk to the LCFN during hip arthroscopy and the minimally invasive anterior approach to the hip.

Nerve injuries in total hip arthroplasty with a mini invasive anterior approach

PURPOSE

Minimal invasive techniques in total hip arthroplasty (THA) have become increasingly popular during recent years. Despite much debate over the outcome of several minimal invasive techniques, complications arising from the use of anterior minimally invasive surgery (AMIS) for THA on a traction table are not well documented. Our study aims to focus on nerve damage during the AMIS procedure and the possible explanations of these injuries.

METHODS

We reviewed all primary THAs performed with the AMIS technique using a traction table, over 5 years and recorded all intraoperative and postoperative complications up to the latest follow-up. We focused on nerve injuries and nerve function impairment following the aforementioned technique.

RESULTS

Our study included 1,512 THAs performed with the AMIS technique in 2 major hip reconstruction centres (KAT General Hospital, Athens, Greece and University Hospital of Geneva, Switzerland), on 1,238 patients (985 women, 253 men; mean age 65.24 years). Mean follow-up was 29.4 months. We observed 51 cases of transient lateral femoral cutaneous nerve neuropraxia (3.37%), 4 cases of femoral nerve paralysis (3 permanent, 1 transient [0.26%]) and 1 case of permanent sciatic nerve paralysis (0.06%). No case of obturator or pudendal nerve injury was noticed. Mean age of these cases was 68.97 years. Sciatic and femoral nerve injuries were confirmed by electromyography, showing axonotmesis of the damaged nerve.

CONCLUSIONS

Neurological injuries are a rare but distinct complication of THAs using the AMIS technique. Possible explanations for such referred nerve injuries are direct nerve injury, extreme traction, hyperextension, extreme external rotation of the leg, use of retractors and coexisting spinal deformities. Controlled use of traction in hip extension, cautious use of retractors and potential use of dynamometers may be useful, so that neurological damage can be avoided. Further studies are needed to fully elucidate the role of the above factors in AMIS neurological complications.

Direct anterior total hip arthroplasty: Literature review of variations in surgical technique

The direct anterior approach to the hip has been suggested to have several advantages compared to previously popular approaches through its use of an intra-muscular and intra-nervous interval between the tensor fasciae latae and sartorius muscles. Recent increased interest in tissue-sparing and minimally-invasive arthroplasty has given rise to a sharp increase in the utilization of direct anterior total hip arthroplasty. A number of variations of the procedure have been described and several authors have published their experiences and feedback to successfully accomplishing this procedure. Additionally, improved understanding of relevant soft tissue constraints and anatomic variants has provided improved margin of safety for patients. The procedure may be performed using specially-designed instruments and a fracture table, however many authors have also described equally efficacious performance using a regular table and standard arthroplasty tools. The capacity to utilize fluoroscopy intra-operatively for component positioning is a valuable asset to the approach and can be of particular benefit for surgeons gaining familiarity. Proper management of patient and limb positioning are vital to reducing risk of intra-operative complications. An understanding of its limitations and challenges are also critical to safe employment. This review summarizes the key features of the direct anterior approach for total hip arthroplasty as an aid to improving the understanding of this important and effective method for modern hip replacement surgeons.

Early functional results after hemiarthroplasty for femoral neck fracture: a randomized comparison between a minimal invasive and a conventional approach

BACKGROUND

A minimal invasive approach for elective hip surgery has been implemented in our institution in the past. It is widely hypothesized that implanting artificial hips in a minimal invasive fashion decreases surgical trauma and is helpful in the rehabilitation process in elective hip surgery. Thereby geriatric patients requiring emergency hip surgery also could theoretically benefit from a procedure that involves less tissue trauma.

METHODS

Sixty patients who sustained a fractured neck of femur were randomly assigned into two groups. In the minimal invasive arm, the so called "direct anterior approach" (DAA) was chosen, in the conventional arm the Watson-Jones-Approach was used for implantation of a bipolar hemi-arthroplasty.Primary outcome parameter was the mobility as measured by the four-item-Barthel index. Secondary outcome parameters included pain, haemoglobin-levels, complications, duration of surgery, administration of blood transfusion and external length of incision. Radiographs were evaluated.

RESULTS

A statistically significant difference (p = 0,009) regarding the mobility as measured with the four-item Barthel index was found at the 5th postoperative day, favouring the DAA. Evaluation of the intensity of pain with a visual analogue scale (VAS) showed a statistically significant difference (p = 0,035) at day 16. No difference was evident in the comparison of radiographic results.

CONCLUSIONS

Comparing two different approaches to the hip joint for the implantation of a bipolar hemi-arthroplasty after fractured neck of femur, it can be stated that mobilization status is improved for the DAA compared to the WJA when measured by the four-item Barthel index, there is less pain as measured using the VAS. There is no radiographic evidence that a minimal invasive technique leads to inferior implant position.

LEVEL OF EVIDENCE

Level II therapeutic study.

The direct anterior approach: initial experience of a minimally invasive technique for total hip arthroplasty

Background

Less invasive approaches for hip arthroplasty have been developed in order to decrease traumatisation of soft tissue and shorten hospital stay. However, the benefits with a new technique can be at the expense of a new panorama of problems. This manuscript describes, with emphasis on postoperative complications, our experience from the first 200 cases of unilateral hip replacement using the direct anterior minimally invasive (MIS) approach.

Methods

A straight incision in front of the greater trochanter was used and the tensor muscle was approached subfascially and retracted laterally. The joint was opened and the femoral head was removed. Usually excellent acetabular exposure was obtained. In order to get access to the proximal femur, the hip capsule was released posterolaterally so that the femur could be lifted using a special retractor behind the tip of the trochanter. After insertion of the prostheses, the wound was closed using running sutures in the fascia overlying the tensor, sub- and intracutaneously.

Results

There was a small influence of BMI on the duration of surgery, and obese patients tended to have the cup positioned at a higher degree of deviation. There were in total 17 complications of which 5 necessitated revision surgery; 3 peroperative femoral fractures and 2 dislocations. Another 4 dislocations were treated with closed reduction and did not recur. 3 cases of nerve injury were noted, all resolved within 12 months. Three cases of DVT were diagnosed as well as 2 cases of postoperative infection; none of these led to chronic disability.

Conclusions

The technique is perhaps more technically demanding than the lateral approaches used today due to the somewhat limited surgical exposure. Morbidly obese or very muscular patients as well as patients with a short femoral neck or acetabular protrusion can represent particular problems. Our results indicate that there are certain risks when adopting this procedure but the complications noted are avoidable.