Piriformis and obturator internus morphology: A cadaveric study

The SPAIRE Approach for Hip Arthroplasty: Short-Term Functional Outcome in an Indian Scenario

Introduction

Hip arthroplasty, including hemiarthroplasty and total hip arthroplasty is a common surgical procedure for patients suffering from hip joint disorders with an aim of complication free early return to activities of daily living. Various minimally invasive surgical approaches have been described to achieve this aim including a relatively new SPAIRE approach. This case series shows our technique of hip arthroplasty using the SPAIRE technique with the help of conventional instruments in an Indian Scenario at a tertiary care center in Eastern India along with our short-term functional outcomes till a follow up period of 6 months.

Materials and method

This was the prospective observational study done between May 2022 to Oct 2023 in Tata Main hospital, Jamshedpur. Total 35 patients were operated by this technique. Data including age, gender, time to return orthotic assisted mobility, Harris hip score at 2 months & any complications till the follow up of 6 months were recorded for each patient who underwent Hemiarthroplasty or Total Hip arthroplasty using the SPAIRE technique with conventional instruments for hip arthroplasty (performed by single surgeon - the senior author) in our tertiary care center.

Results

35 patients were operated during this span by using the SPAIRE technique. There were 30 cases of hip hemiarthroplasty and 5 cases of total hip arthroplasty (1 bilateral). 5 patients were lost to follow up during the period of 6 months. Harris hip score was measured for each patient at 2 months and mean Harris hip score was 83.16. Out of 35 patients, 9 patients had excellent outcome, 14 patients had good outcome and 7 patients had fair outcome. No patient had complications such as infection, delayed wound healing, periprosthetic fractures or sciatic nerve injury. One patient reported dislocation at 3 months following a fall. Mean time to return to orthotic assisted ambulation was 1.5 days for all 35 patients.

Conclusion

SPAIRE technique is one of the safe surgical approaches for primary hip arthroplasties. This minimally invasive tendon sparing approach which preserves quadricep coxa provides excellent hip stability, early return to preinjury activities. It also reduces postoperative complications such as dislocation.

The short external rotators in the anterior approach hip arthroplasty: do the tendons heal or not? A prospective MRI study

INTRODUCTION

Release of some of the short external rotator tendons may be needed in the direct anterior approach (DAA) for Total Hip Arthroplasty (THA). It is unknown if these tendons heal. The purpose of this prospective study is to examine short external rotator tendon healing after release and the associated effect on muscle volume. In addition, we examined the relation with external rotation force and patient reported outcome measures (PROMs).

METHODS

In 21 DAA THA patients, preoperative MRI was compared with postoperative MRI at 6 weeks and 12 months. PROMs and rotation force of both hips were assessed. Tendon integrity and muscle volume of the obturator internus and piriformis were assessed on MRI using dedicated software.

RESULTS

In 5 patients all tendons remained intact, in 4 patients only the conjoined tendon was released and in 12 patients both the conjoined and piriformis were released. Obturator externus remained intact in all patients. In patients with tendon release, mean volume of obturator internus and piriformis muscle decreased 27% (SD 11) and 23% (SD 16) 6 weeks after surgery, respectively. Released tendons and muscle volume loss did not recover 12 months after surgery. We found no relation between tendon release and hip rotation force or PROMs.

CONCLUSIONS

We found absent tendon healing and muscle volume loss when the conjoined or piriformis tendons were released. Although we found no relation between tendon detachment and hip force or PROMs, we have adapted our operative technique to make it more preserving for the piriformis.

Bilateral absence: A rare anomaly of the gemelli muscles

The superior and inferior gemelli are deep muscles of the gluteal region, that facilitate the maintenance of a dynamic stability of the hip joint. Their absence could increase the chances of failure in the management of total hip anthroplasty and column acetabular ring fractures. We present a case of an adult female cadaver, with bilateral absence of the superior and inferior gemelli muscles.

Piriformis: Sparing approach, is it better?

Hip fractures as well as coxarthrosis are conditions that are becoming more common in everyday orthopedic practice. With the aging of the world's population, there is an increasing need for partial (HA) or total hip arthroplasty (THA). No elective procedure is as important to quality of life as total hip arthroplasty, and partial hip arthroplasty is a method of treatment in elder population who suffered fracture of the femoral neck. There are several hip approaches that can be used for arthroplasty. Hip dislocation is a serious complication after hip arthroplasty and occurs somewhat more frequently when the posterior hip approach is used. The aim of this study is to show that the piriformis sparing technique gives better results in terms of reducing the frequency of dislocations in the early postoperative period (one year). We operated od 249 patients, and after follow-up that lasted from 13 to 22 months we had four dislocations, three in patient with THA(0.021) and one after HA(0.009). Preservation of the piriformis tendon is a minor modification in the operative technique that can lead to a great benefit in the quality of treatment and a reduced risk of complications.

Minimally invasive posterolateral hip approach with SPARTAQUUS (Spare the Piriformis And Respect The Active QUadratus femoris and gluteus mediUS) technique

Interest in the different surgical approaches to total hip arthroplasty remains high, but without any real consensus on which approach is the most beneficial. Several recent technical innovations have made it possible to reduce the risk of dislocation, therefore improving the efficacy of the posterolateral approach. Since 2003, we have been using a modified minimally invasive posterolateral approach called SPARTAQUUS (Spare the Piriformis And Respect The Active QUadratus femoris and gluteus mediUS), which spares the piriformis tendon, the quadratus femoris muscle and the gluteus medius muscle, and involves direct capsular repair. The "active posterosuperior hammock" effect of the piriformis tendon is therefore coupled with the "passive posterosuperior hammock" effect of the capsular repair, thus limiting the risks of posterior dislocation of the prosthetic hip joint.

Architecture of the Short External Rotator Muscles of the Hip

Background

Muscle architecture, or the arrangement of sarcomeres and fibers within muscles, defines functional capacity. There are limited data that provide an understanding of hip short external rotator muscle architecture. The purpose of this study was thus to characterize the architecture of these small hip muscles.

Methods

Eight muscles from 10 independent human cadaver hips were used in this study (n = 80 muscles). Architectural measurements were made on pectineus, piriformis, gemelli, obturators, quadratus femoris, and gluteus minimus. Muscle mass, fiber length, sarcomere length, and pennation angle were used to calculate the normalized muscle fiber length, which defines excursion, and physiological cross-sectional area (PCSA), which defines force-producing capacity.

Results

Gluteus minimus had the largest PCSA (8.29 cm²) followed by obturator externus (4.54 cm²), whereas superior gemellus had the smallest PCSA (0.68 cm²). Fiber lengths clustered into long (pectineus - 10.38 cm and gluteus minimus - 10.30 cm), moderate (obturator internus - 8.77 cm and externus - 8.04 cm), or short (inferior gemellus - 5.64 and superior gemellus - 4.85). There were no significant differences among muscles in pennation angle which were all nearly zero. When the gemelli and obturators were considered as a single functional unit, their collective PCSA (10.00 cm²) exceeded that of gluteus minimus as a substantial force-producing group.

Conclusions

The key findings are that these muscles have relatively small individual PCSAs, short fiber lengths, and low pennation angles. The large collective PCSA and short fiber lengths of the gemelli and obturators suggest that they primarily play a stabilizing role rather than a joint rotating role.

Soft tissue restrictors of femoral elevation in direct anterior approach-an anatomic study

Background

With the patient in a constant supine position, elevation of the femur in THA (DAA) provides a more intuitive and conducive location of the acetabulum for the correct placement of the acetabular prosthesis, but elevation of the femur for broaching becomes more challenging. The purpose of this study is to analyze the restriction of the ischiofemoral ligament and short external rotation muscles, and its effect on the elevation of the proximal femur in the DAA.

Methods

The study subjects comprised 5 freshly frozen cadavers with 10 normal hips. All of the anatomic dissections of all of the hips were performed through the DAA. The ischiofemoral ligament, piriformis, conjoint tendon, and external obturator were successively resected. All of the proximal femurs of the specimens were levered by a point tip curved retractor that was connected with a dynamometer. Through preliminary measurements, an applied force of 80 N was adopted and maintained on the curved retractor. The experiment was repeated to measure the displacement of the proximal femur being raised after the posterior structures of the hip joint had been resected in a stepwise fashion. The displacement of the retractor was recorded, and the data were then analyzed.

Results

The distance significantly increased after the ischiofemoral ligament was severed (P < 0.001). A prominent increase was demonstrated after the conjoint tendons were severed (P < 0.001). The distance insignificantly increased after the piriformis was severed (P > 0.05). After the obturator externus was cut off, the distance increased by an insignificant amount (P > 0.05).

Conclusion

In DAA, the ischiofemoral ligament contributed stability when the femur was being raised. The main contribution of restriction was provided by the conjoint tendon. The tendons of the obturator externus muscle and piriformis muscle did not provide any significant restriction when the femur was being raised.

LENGTH CHANGE OF THE SHORT EXTERNAL ROTATORS OF THE HIP IN COMMON STRETCH POSITIONS: A CADAVERIC STUDY

Background

Stretching of the deep rotators of the hip is commonly employed in patients with lumbosacral, sacroiliac, posterior hip, and buttock pain. There is limited research demonstrating the effectiveness of common stretching techniques on the short external rotators of the hip.

Purpose

The objective of this study was to evaluate length change during stretching of the superior and inferior fibers of the piriformis, superior gemellus, obturator internus, and inferior gemellus.

Study Design

Repeated-measures laboratory controlled cadaveric study.

Methods

Seventeen hip joints from nine embalmed cadavers (5 male; 4 female) with an age between 49-96 years were skeletonized. Polypropylene strings were attached from the origin to insertion sites of the short external rotators. The change of length (mm) noted by excursion of the strings was used as a proxy for change in muscle length, when the hip was moved from the anatomical position to four specific stretch positions: 1) 45 ° internal rotation from hip neutral flexion/extension, 2) 45 ° external rotation from 90 ° hip and knee flexion, 3) 30 ° adduction from 90 ° of hip and knee flexion, and 4) 30 ° of adduction with the hip and knee flexed so the lateral malleolus contacted the lateral femoral epicondyle of the contralateral limb , were recorded.

Results

There was a significant effect on string displacement by stretch position, F (15,166) = 14.67, p < .0005; Wilk's L = .097, partial n2 = .540. The greatest displacement of the strings corresponding to the superior piriformis, inferior piriformis, and the superior gemellus occurred in 30 ° adduction from 90 ° of hip and knee flexion. The obturator internus and inferior gemellus had the largest string displacement with 45 ° internal rotation from neutral flexion/extension.

Conclusions

While all stretch positions caused a significant string displacement indicating length changes of the deep rotators of the hip, the three stretch positions that caused the greatest change were: 1) 30 ° adduction from 90 ° of hip and knee flexion, 2) 45 ° internal rotation from neutral flexion/extension, and 3) 45 ° external rotation with 90 ° hip and knee flexion.

Clinical Relevance

This study has clinical implications for the effectiveness of specific stretching techniques on the short external rotators of the hip with the potential to improve the validity of stretching protocols for patients with posterior hip or buttock pain. The piriformis and superior gemellus had a larger change in length when adducting the hip from 90 ° degrees of hip and knee flexion. The obturator internus and inferior gemellus had a greater length change when internally rotating the hip from neutral flexion/extension.

Level of Evidence

3.

The SPAIRE technique allows sparing of the piriformis and obturator internus in a modified posterior approach to the hip

INTRODUCTION

The Sparing Piriformis and Internus, Repair Externus (SPAIRE) technique allows a muscle sparing mini-posterior approach to the hip.

METHOD

We present in this article a description of an adaptation of the familiar posterior approach (PA) in which the only tendon released is obturator externus. Termed SPAIRE, this muscle sparing technique enables preservation of the piriformis tendon and conjoint insertion of obturator internus and the gemelli. The technical description allows for safe and reliable replication by any surgeon familiar with the posterior approach (PA) to the hip without reliance on additional equipment, and without compromising the ability to convert into a more extensile approach.

CONCLUSIONS

This technical description and brief discussion of rationale outlines the ongoing work of the authors in developing the SPAIRE technique as part of the spectrum of the posterior approach to the hip. The senior author now uses this technique routinely for total hip replacements and hemiarthroplasty. Patients are mobilised with no postoperative restrictions whatsoever. Other potential advantages include improved gait, more anatomical restoration of hip function, and enhanced stability. Projects have been initiated in our unit to objectively assess the possible clinical advantages relating to use of the SPAIRE technique using gait analysis, objective measurement of muscle power and studies of hip stability.

Obturator internus muscle strains

We report 2 cases of obturator internus muscle strains. The injuries occurred in young male athletes involved in kicking sports. Case 1 details an acute obturator internus muscle strain with associated adductor longus strain. Case 2 details an overuse injury of the bilateral obturator internus muscles. In each case, magnetic resonance imaging played a crucial role in accurate diagnosis.

Radiographic Identification of Arthroscopically Relevant Proximal Femoral Structures

BACKGROUND

Anatomic landmarks located on the proximal femur have only recently been defined, and there is a lack of radiographic guidelines for their locations presented in the literature. With the confident identification of these landmarks, radiographs could provide more assistance in preoperative evaluations, intraoperative guidance, and postoperative assessments.

PURPOSE

To quantify the radiographic locations of endoscopic landmarks of the proximal femur.

STUDY DESIGN

Descriptive laboratory study.

METHODS

Ten cadaveric specimens were dissected, and radio-opaque hardware was placed for each landmark of interest. Radiographs were obtained and measurements recorded in anteroposterior (AP) and Dunn 45° views.

RESULTS

In the AP view, the gluteus medius insertion was located a mean 12.9 ± 2.4 mm and 34.7 ± 5.1 mm from the piriformis fossa and vastus tubercle, respectively. The piriformis fossa was a mean 14.8 ± 5.9 mm and 4.9 ± 1.9 mm from the anterior and posterior tips of the greater trochanter, respectively. The anterior and posterior tips of the greater trochanter were a mean 14.8 ± 5.1 mm from each other. In the Dunn 45° view, the piriformis fossa was a mean 13.3 ± 2.0 mm, and the vastus tubercle was a mean 21.5 ± 6.0 mm, from the gluteus medius insertion. Moreover, the vastus tubercle was a mean 33.5 ± 6.4 mm from the anterior tip of the greater trochanter and 31.6 ± 8.5 mm from the posterior tip of the greater trochanter.

CONCLUSION

In spite of the variation in cadaveric sizes, quantitative descriptions of endoscopic landmarks were reproducible in clinical views.

CLINICAL RELEVANCE

A detailed understanding of how the described landmarks present radiographically is relevant to preoperative planning, intraoperative evaluations, and postoperative assessments.

An appraisal of the short lateral rotators of the hip joint

The short lateral rotators (piriformis, obturator internus, superior and inferior gemelli, obturator internus, and quadratus femoris) are functionally important muscles, significantly contributing to hip joint stability. They act as "postural muscles", holding the femoral head in the acetabulum during hip movements, thus are frequently monitored in gait analysis and for muscle rehabilitation post-injury. Despite the need to precisely identify and repair these muscles for stability postoperatively, clinical complications have resulted from the inadequate and inconsistent understanding of their morphological and functional anatomy. Furthermore, the short lateral rotators have complex entheses (osteotendinous insertions on bone) and may be subject to overuse injury in sport. This study aims to review the reported morphology of the short lateral rotators in order to ascertain whether discrepancies exist in our understanding of these muscles, and if further investigation is required to aid in gait analysis, clinical management of hip pathologies, and prevention of overuse injuries. Following a literature search strategy, 59 primary references were retrieved from three databases, with additional 26 anatomical textbooks selected for critical evaluation. Numerous inaccuracies and inconsistencies in the anatomical descriptions of the attachments, patterns of innervation and actions exist, and often insufficiently supported by primary findings. There is also a paucity of information regarding the architectural pattern of the muscles, which would be useful in clarifying the function of these dynamic stabilizers of the hip joint. A better anatomical understanding of these muscles will better inform hip reconstruction and lead to improved surgical outcomes by reducing post-operative complications.

Surgically Relevant Bony and Soft Tissue Anatomy of the Proximal Femur

Background:

Hip endoscopy facilitates the treatment of extra-articular disorders of the proximal femur. Unfortunately, current knowledge of proximal femur anatomy is limited to qualitative descriptions and lacks surgically relevant landmarks.

Purpose:

To provide a quantitative and qualitative analysis of proximal femur anatomy in reference to surgically relevant bony landmarks.

Study Design:

Descriptive laboratory study.

Methods:

Fourteen cadaveric hemipelvises were dissected. A coordinate measuring device measured dimensions and interrelationships of the gluteal muscles, hip external rotators, pectineus, iliopsoas, and joint capsule in reference to osseous landmarks.

Results:

The vastus tubercle, superomedial border of the greater trochanter, and femoral head-neck junction were distinct and reliable osseous landmarks. The anteroinferior tip of the vastus tubercle was 17.1 mm (95% CI: 14.5, 19.8 mm) anteroinferior to the center of the gluteus medius lateral insertional footprint and was 22.9 mm (95% CI: 20.1, 25.7 mm) inferolateral to the center of the gluteus minimus insertional footprint. The insertions of the piriformis, conjoint tendon of the hip (superior gemellus, obturator internus, and inferior gemellus), and obturator externus were identified relative to the superomedial border of the greater trochanter. The relationship of the aforementioned footprints were 49% (95% CI: 43%, 54%), 42% (95% CI: 33%, 50%), and 64% (95% CI: 59%, 69%) from the anterior (0%) to posterior (100%) margins of the superomedial border of the greater trochanter, respectively. The hip joint capsule attached distally on the proximal femur 18.2 mm (95% CI: 14.2, 22.2 mm) from the head-neck junction medially on average.

Conclusion:

The vastus tubercle, superomedial border of the greater trochanter, and the femoral head-neck junction were reliable osseous landmarks for the identification of the tendinous and hip capsular insertions on the proximal femur. Knowledge of the interrelationships between these structures is essential for endoscopic navigation and anatomic surgical repair and reconstruction.

Clinical Relevance:

The qualitative and quantitative clinically relevant anatomic data presented here will aid in the diagnosis of proximal femur pathology and will provide a template for anatomic repair or reconstruction.