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Safe Zones for Anterior Acetabular Retractor Placement in Direct Anterior Total Hip Arthroplasty: A Cadaveric Study
Abstract
Introduction:
There is paucity of literature evaluating anterior acetabular retractor proximity to the femoral nerve and external iliac vessels during total hip arthroplasty through the direct anterior approach. In this cadaveric study, we evaluated three retractor locations to identify optimal positioning of anterior retractors.
Methods:
A direct anterior approach was performed in 22 hips of 15 cadavers. Anterior acetabular retractors were placed over the anterior acetabular wall in-line with the femoral neck (12-o'clock or middle position). The anterior neurovascular structures were identified through the ilioinguinal approach. Retractors were reinserted at 10-o'clock (right hip; superior) and 2-o'clock (right hip; inferior) locations marked using K-wires. Horizontal and vertical distances from retractor tip positions to neurovascular structures were measured with a digital caliper.
Results:
Retractor tips moved significantly from lateral to the femoral nerve when placed in the superior position (mean, 2.8 mm) to medial to the femoral nerve in the middle (mean, -2.3 mm) and inferior (mean, -4.8 mm) locations. Retractor tips moved significantly medial toward the external iliac artery when retractors were moved from superior (mean, 15.3 mm) to inferior (mean, 6.6 mm) positions placing the retractor tip closer to the vessels.
Conclusion:
As retractor placements moved inferior, retractor tips moved medial to neurovascular structures. Inferior retractor positioning placed the femoral nerve and external iliac artery at the risk of injury during the initial retractor placement or adjustment. Retractors should be placed in a relative safe zone superior to the 12-o'clock position to avoid damage to neurovascular structures.
Level of evidence:
IV.
... In a separate study, Ishimatsu et al. conducted intraoperative nerve monitoring and found that migration inferiorly along the anterior acetabular wall decreased the distance to the femoral nerve 33 . Another cadaveric study by Sullivan et al. corroborated these findings 35 . They reported that superior placement of the anterior acetabular retractor was a relative safe position to protect against iatrogenic femoral nerve palsy with DAA THA 35 (Fig. 2). ...
... Another cadaveric study by Sullivan et al. corroborated these findings 35 . They reported that superior placement of the anterior acetabular retractor was a relative safe position to protect against iatrogenic femoral nerve palsy with DAA THA 35 (Fig. 2). ...
... Other modifiable risk factors implicated in femoral nerve palsy include dynamic hip external rotation, hyperextension, and adduction performed during femoral broaching and intraoperative evaluation of hip stability. These risk factors have been reported to lead to stretch injury and ischemia 35 . Keeping the operative lower extremity out of manual traction while performing these actions could potentially avoid these complications. ...
While no single approach for total hip arthroplasty (THA) has been proven to be superior to others in terms of patient outcomes, the direct anterior approach (DAA) is becoming increasingly popular. » All of the described techniques for THA carry a small risk of nerve injury. » Identifying risk factors for nerve injury and mitigating these risks where feasible are imperative in order to reduce the incidence of this complication with any approach for THA.
... The direct anterior approach (DAA) for hip arthroplasty has become popular, despite the relatively higher rate of complications, including femoral nerve injury [6]. Several anatomical and radiological studies reported the femoral neurovascular bundle location in the DAA [7][8][9], but these studies evaluated the static anatomy. The influence of leg position during surgery is not considered in these studies, although extension and external rotation of the hip are required during the exposure of the acetabulum and femur in the DAA. ...
... Anticoagulation, excessive limb lengthening, and acetabular rim retractor placement are associated with neurovascular injury [18,2]. A cadaveric study reported the inferior retractor placements to the acetabulum is at risk of neurovascular injury and the safe zone of anterosuperior acetabular retractor placement for DAA [9]; however, the measurement was only in a static position. The retractor is usually placed on the anterior acetabular rim during the exposure; therefore, we defined the edge of the anterior acetabulum as a reference point for radiographic assessment. ...
Background
Femoral neurovascular injury is a serious complication in a direct anterior approach (DAA) total hip arthroplasty. However, dynamic neurovascular bundle location changes during the approach were not examined. Thus, this study aimed to analyze the effects of leg position on the femoral neurovascular bundle location using magnetic resonance imaging (MRI).
Methods
This study scanned 30 healthy volunteers (15 males and 15 females) with 3.0T MRI in a supine and 30-degree hip extension position with the left leg in a neutral rotation position and the right leg in a 45-degree external extension position. The minimum distance from the edge of the anterior acetabulum to the femoral nerve (dFN), artery, and vein were measured on axial T1-weighted images at the hip center level, as well as the angle to the horizontal line of the femoral nerve (aFN), artery (aFA), and vein from the anterior acetabulum.
Results
The dFN in the supine position with external rotation was significantly larger than supine with neutral and extension with external rotation position (20.7, 19.5, and 19.0; p = 0.031 and 0.012, respectively). The aFA in supine with external rotation was significantly larger than in other postures (52.4°, 34.2°, and 36.2°, p < 0.001, respectively). The aFV in supine with external rotation was significantly larger than in supine with a neutral position (52.3° versus 47.7°, p = 0.037). The aFN in supine and external rotation was significantly larger than other postures (54.6, 38.2, and 33.0, p < 0.001, respectively).
Conclusions
This radiographic study revealed that the leg position affected the neurovascular bundle location. These movements can be the risk of direct neurovascular injury or traction.
... Another cadaveric study using computed tomography scans demonstrated that retractor placement at the region of the anterior inferior iliac spine was furthest from the neurovascular bundle. 34 Similarly, Sullivan and colleagues 48 found that placing the anterior retractor superiorly helped to mitigate the risk of femoral nerve injury in DA THA. Consistent with these findings, Ishimatsu and colleagues 44 performed intraoperative neuromonitoring and noted that moving the retractors inferiorly along the acetabular rim brought it into closer proximity to the femoral nerve. ...
... 42,45 Another common cause is femoral nerve stretching from excessive limb-lengthening, a finding that has also been reported in studies on nonanterior approaches. 2,5,10,50 Additionally, hyperextension, extension, and adduction maneuvers during broaching and trialing may predispose to femoral nerve injury, 48 although this may be avoided by reducing traction on the limb. Thermal injury, iatrogenic laceration, and compression of nerve by hematoma from aggressive anticoagulation are other known causes of femoral nerve injury. ...
Nerve injuries following total hip arthroplasty are rare but devastating complications. The most important modifiable risk factor remains the choice of hip approach and surgical technique applied. The risk of nerve injuries is related to technical complexity of the procedure and anatomic variability of the nerves. Surgeons should remain cognizant of inherent risk factors, variations in the course and branching patterns of different nerves, and technical considerations of the surgical approach to mitigate risks. This article reviews the literature on postsurgical nerve injuries following total hip arthroplasty and characterizes the influence of surgical approach on the risk of this complication.
... The etiology is poorly understood, but may involve damage by a retractor due to the closeness of the FN and AA. To minimize the risk of femoral nerve palsy, several reports suggest the suitable retractor position or insertion length [5,15,17], though these subjects were normal hip joints. The lack of evidence regarding the FN to AA distance in OA hips led to the current study, and there were three main findings. ...
... Given these possible mechanisms, the FN to AA distance may be correlated with the risk for femoral nerve injury and it would be better to place a retractor where the FN is more distant. Previous reports suggested that retractors should be placed around the AIIS or superior to the 3 or 9 o'clock position of the AA to avoid damage to neurovascular structure [15,17]. In the current study, the mean FN to AA distances in OA hips were 19.4 to 24.3 mm in these areas, 18.8 to 23.6 mm in females, and 21.4 to 26.8 mm in males. ...
Background
The appropriate position of retractors to minimize the risk of femoral nerve palsy remains uncertain. The purpose of this imaging study was to evaluate the distance between the femoral nerve (FN) and anterior acetabulum (AA) in hip osteoarthritis (OA).
Methods
Forty-one patients with unilateral hip OA underwent magnetic resonance imaging. Three measurement levels were defined and the minimum distance between the femoral nerve (FN) margin and anterior acetabulum (AA) rim was measured on axial T1-weighted images on the OA and normal sides at each level, with reference to an advanced neurography view. The cross-sectional area (CSA) of the iliopsoas muscle was also measured at each level bilaterally by three observers. Distances and CSAs were compared between the OA and normal side. Multiple regression analysis was performed to identify variables associated with the distance in OA.
Results
The mean minimum FN to AA distances in OA were 19.4 mm at the top of the anterior inferior iliac spine (AIIS), 24.3 mm at the bottom of the AIIS, and 21.0 mm at the tip of the greater trochanter. These distances were significantly shorter than in normal hips at the top and bottom of the AIIS, with mean differences of 1.6 and 5.8 mm, respectively (p = 0.012, p < 0.001). CSAs of the iliopsoas in OA were significantly smaller at all levels (all p < 0.001), with reductions of 10.5 to 17.9%. The CSA of the iliopsoas at the bottom of the AIIS was associated with the FN to AA distance at the same level (p = 0.026). Interobserver reliabilities for measurements were very good to perfect (intraclass correlation coefficients 0.897 to 0.966).
Conclusions
To minimize the risk of femoral nerve palsy, surgeons should consider the change of the femoral nerve to anterior acetabulum distance in osteoarthritic hip surgery.
... The neurovascular bundle that contains the external iliac artery travels along the iliopsoas muscle. The iliopsoas muscle bulk will protect the neurovascular bundle against injury (Sullivan et al. 2019). Therefore, the retractor tips should be placed directly on the bone, and the iliopsoas muscle should not be interposed between the retractor and bone (Rue et al. 2004). ...
... Neither drills nor screws were necessary to fix the acetabular component. Because the iliac vessels run along the iliacus muscles the retractor has to cross the iliopsoas muscle to cause direct damage to the external iliac artery (Kawasaki 2012, Sullivan et al. 2019). In our case we had no indication during surgery that the Hohmann retractors were located out of the correct anatomical location and we do not believe they were inserted too deep or medially. ...
... An excessively medial exposure of the hip joint can be a significant contributor to the incidence of postoperative neurological complications [23,24]. The wrong anterior intermuscular interval inevitably reduces the thickness of soft tissues protecting the femoral neurovascular bundle, which can be compressed or injured by retractors [25,26]. Likewise, violation of the connective tissue surrounding the neurovascular bundle can trigger the formation of hematoma or swelling of the soft tissues, which can compress the neurovascular structures. ...
Background
The direct anterior approach is increasingly used for primary total hip arthroplasty (THA) due to its minimally invasive nature and rapid recovery time. Difficulties in identifying the correct intermuscular interval can arise during the procedure, sometimes resulting in excessive medial exposure. This study aimed to evaluate demographics and risk factors, outcomes, and potential complications in those THA patients in which a medialized approach was performed.
Methods
We retrospectively reviewed cases of anterior THA to identify cases where the surgical approach to the hip was more medial than the standard interval. Demographic data, operative time, blood loss, intraoperative and postoperative complications, radiographic findings were collected and compared with a control group of 50 THA performed using the standard anterior intermuscular interval.
Results
In a series of 1,450 anterior total hip arthroplasty (THA) procedures performed between January 2018 and December 2021, with an average follow-up of 33 ± 22.3 months, six patients (0.4%) had a medialized surgical interval. In one case the superficial layer was medial to the sartorious muscle while in the other five cases, the interval was lateral to the sartorius superficially, and medial to the rectus femoris deeply. Four out of 6 patients (66.6%) showed neuropraxia affecting the femoral nerve, and 3 out of 6 (50%) had involvement of the lateral femoral cutaneous nerve. In 6 out of 6 patients (100%), surgery was performed during the learning curve of DAA. No patients in the control group developed femoral nerve neuropraxia, and 2 out of 50 patients (4%) showed involvement of the lateral femoral cutaneous nerve.
Discussion and conclusion
The anterior approach can rarely result in excessive medial exposure to the hip joint, especially during the learning curve. In our study cohort, an increased rate of neurological complications and reduced outcomes were observed, thereby rendering this event of particular clinical significance. To avoid unconventional intermuscular intervals, patient positioning and correct identification of the muscle bellies by recognizing the orientation of the muscle fibers are useful, together with the identification and ligation of the circumflex vessels, to ensure the identification of the correct intermuscular interval.
... Sullivan et al. [18] conducted a study on 22 hips from 15 lightly embalmed cadavers using the direct anterior approach and applied the anterior retractor. Their findings revealed that the mean horizontal distance from the retractor tip to the femoral nerve was 2.8 mm at the superior retractor position, -2.3 mm at the retractor middle position, and −4.8 mm at the inferior retractor position (p-value < 0.001). ...
Purpose
This study aimed to investigate the distance and correlation between the anatomy of the anterior side of the hip joint and the femoral nerve.
Methods
Using ten fresh-frozen cadavers with twenty hip joints. We dissected and marked the femoral nerve in the inguinal area. Employing the direct anterior approach, we identified and marked study points, including the superior and inferior points of the anterior rim of the acetabulum, ¼ point, half point, and ¾ point along an imagined line connecting the formers, the inferomedial and mid aspect of the femoral neck, and the soft spot. Coronal plane measurements gauged the distance between these points and the femoral nerve. The collected data were analyzed to assess the distance and correlation.
Results
In the coronal plane, the median distance between the inferior point of the anterior rim of the acetabulum and the femoral nerve was 0 millimeters (interquartile range [IQR] 0–0). Likewise, the median distance between the mid aspect of the medial side of the femoral neck and the femoral nerve was 0 millimeters (IQR 0–0). Additionally, the mean distance between the soft spot and the femoral nerve was 1.18 cm (SD 0.63).
Conclusion
Surgeons approaching the hip joint via the direct anterior approach should be cautious at the inferior point of the anterior rim of the acetabulum and the mid aspect of the femoral neck. The soft spot at the anterior rim of the acetabulum remains safe from direct injury when surgeons use the correct technique during anterior retractor insertion.
... Femoral nerve injury, although infrequent, has been reported in DAA THR surgery. Cadaveric studies have highlighted that the position of the acetabular retractor tip may be as close as 2.8 mm to the nerve during DAA and anterior retractors can inadvertently stretch the femoral nerve [15,51,53]. In this study, the lead surgeon placed the retractors himself to avoid inadvertent stretching of the nerve, with the medial retractor placed at 7-8 o'clock position for preparation of a left acetabulum. ...
Purpose
The purpose of this study was to report all complications during the first consecutive 865 cases of bikini incision direct anterior approach (DAA) total hip arthroplasty (THA) performed by a single surgeon. The secondary aims of the study are to report our clinical outcomes and implant survivorship. We discuss our surgical technique to minimize complication rates during the procedure.
Methods
We undertook a retrospective analysis of our complications, clinical outcomes and implant survivorship of 865 DAA THA’s over a period of 6 years (mean = 3.9yrs from 0.9 to 6.8 years).
Results
The complication rates identified in this study were low. Medium term survival at minimum 2-year survival and revision as the end point, was 99.53% and 99.84% for the stem and acetabular components respectively. Womac score improved from 49 (range 40–58) preoperatively to 3.5(range 0–8.8) and similarly, HHS scores improved from 53(range 40–56) to 92.5(range 63–100) at final follow-up (mean = 3.9 yrs) when compared to preoperative scores.
Conclusions
These results suggest that bikini incision DAA technique can be safely utilised to perform THA.
... Finally, this technique avoids the placement of sharp retractors over the rim of the acetabulum, potentially decreasing the risk of injury to nearby neurovascular structures. 19 conclusion A hands-free, all self-retaining retraction technique was found to be useful during acetabular preparation in DA THA. This technique is safe and provides improved exposure over the traditional three-retractor method. ...
Acetabular exposure for direct anterior (DA) total hip arthroplasty (THA) can be performed using hands-free, self-retaining retractors. No current study quantitatively compares this self-retaining technique with the traditional manual technique. In 65 consecutive DA THA hips, two “best-view” digital photographs were taken of the exposure—one using Charnley/self-retaining retractors and one using a traditional three-retractor manual technique. Percent exposure of the polyethylene liner was calculated. Percent acetabular exposure averaged 80.0% using the Charnley/self-retaining technique, compared with 73.1% using the manual technique (P=.0002). A hands-free technique provides superior acetabular exposure compared with the manual technique. Increasing body mass index predicts decreasing exposure with both techniques. [Orthopedics. 2021;44(2):e309–e313.]
Neurological injuries are rare but significant complications of revision total hip arthroplasty (THA) that can lead to substantial patient disability. This chapter explores the causes and mechanisms of nerve injury following revision THA, including ischemia, compression, traction, and laceration, and provides an overview of their classifications and diagnostic methods. Key topics include the anatomy and regeneration processes of peripheral nerves, the use of diagnostic tools to complement clinical evaluation, including electrodiagnostic studies and MR neurography, and the identification of patient and procedural risk factors like developmental hip dysplasia, prior spinal surgeries, limb lengthening, and surgical approach. Treatment strategies range from supportive care and physical therapy to surgical interventions like nerve decompression and hematoma evacuation. Early diagnosis, effective management, and preventative strategies, including meticulous surgical technique and intraoperative monitoring, are crucial in mitigating risks and improving functional recovery. Comprehensive patient education and counseling are integral to setting realistic postoperative expectations.
This chapter explores vascular injuries in total hip arthroplasty (THA), emphasizing their rarity yet critical implications. It delves into the intricate vascular anatomy surrounding the hip joint and identifies vulnerable regions susceptible to injury during surgery. Mechanisms of injury, including direct trauma and thermal damage from cement polymerization, are discussed alongside predisposing factors such as altered anatomy and previous surgeries. Prevention strategies encompass preoperative assessment, meticulous surgical planning, and intraoperative precautions to mitigate risks. Prompt recognition and management of vascular injuries are essential, necessitating effective communication and collaboration among surgical teams and vascular specialists. Techniques for temporary and definitive control of bleeding are outlined, highlighting the importance of surgical approaches and endovascular interventions. By fostering a comprehensive understanding of vascular anatomy and implementing proactive management strategies, orthopedic surgeons can enhance patient safety and optimize outcomes in THA surgeries.
Background:
There is limited literature on motor nerve palsy in modern total hip arthroplasty (THA). The purpose of this study was to establish the incidence of nerve palsy following THA using the direct anterior (DA) and postero-lateral (PL) approaches, identify risk factors, and describe the extent of recovery.
Methods:
Using our institutional database we examined 10,047 primary THAs performed between 2009 and 2021 using the DA (6,592; 65.6%) or PL (3,455; 34.4%) approach. Postoperative femoral (FNP) and sciatic/peroneal (PNP) nerve palsies were identified. Incidence and time to recovery was calculated, and association between surgical and patient risk factors and nerve palsy were evaluated using Chi-square tests.
Results:
The overall rate of nerve palsy was 0.34% (34/10,047), and was lower with the DA approach (0.24%) than the PL approach (0.52%), P=0.02. The rate of FNPs in the DA group (0.20%) was 4.3-times higher than the rate of PNPs (0.05%), while in the PL group the rate of PNPs (0.46%) was 8-times higher than FNPs (0.06%). Higher rates of nerve palsy were observed with women, shorter patients, and non-osteoarthritis pre-operative diagnoses. Full recovery of motor strength occurred in 60% of cases with FNP and 58% of cases with PNP.
Conclusion:
Nerve palsy is rare after contemporary THA through the PL and DA approaches. The PL approach was associated with a higher rate of PNP, whereas the DA approach was associated with a higher rate of FNP. Femoral and sciatic/peroneal palsies had similar rates of complete recovery.
Total hip replacement is a highly effective surgical procedure for patients suffering from end-stage osteoarthritis. However, like any other surgical procedure, total hip replacement may have associated surgical complications. This chapter will explore and describe the complications directly associated with total hip arthroplasty performed with the anterior-based muscle-sparing (ABMS) surgical approach, including nerve injuries, intraoperative periprosthetic fractures, and postoperative dislocations. The surgical anatomy and the causative factors of the complications will be discussed, and for each of them, tips and tricks to avoid them will be proposed.KeywordsTotal hip replacementAnterior-based muscle-sparing (ABMS)ComplicationNerve injuryHip dislocationIntraoperative periprosthetic fractures
This chapter explores the benefits of a standard incision for the approach to anterior total hip arthroplasty and identifies keys in the exposure for achieving adequate hemostasis, avoiding complications, and maximizing surgical efficiency. This will also highlight current evidence and anatomic considerations throughout the approach and detail some pearls and pitfalls for its use in current practice.KeywordsDirect anterior THAAnterior approachStandard incisionExtensile anterior approachHueter approachSmith-Petersen approach
The ideal hip replacement relieves pain and restores joint function. Anatomic reconstruction with attention to mechanical force balance is essential for longevity. This can be achieved through careful attention to the summative parameters of global offset and leg length. With these parameters in mind, surgeons can reliably reconstruct optimal functional joint mechanics in most cases. The anterior approach to the hip offers distinct advantages toward achieving this goal compared to lateral and posterolateral approaches.
Introducing the direct anterior approach (DDA) to the hip joint in a university hospital is a multilevel challenge. A good preparation of the whole team includes multiple changes: changed patient information, adapted rehabilitation for the physiotherapist, shorter hospitalization and organization time for the social workers, knowledge and use of the instruments and HANA-table for operating room staff, changed but simplified after-care on the wards, and acquisition of surgeons’ knowledge and skills. The whole department has to be familiar with the new methods. Surgical preparation includes training of the technique to understand new anatomical references, material, pitfalls, and choice of the right patient and anticipating intraoperative challenges with the new technique. Fellowships and cadaveric dissections are good options to learn, reduce complications, and shorten the learning curve. Choosing simple first cases is challenging and needs a well-founded selection to prevent complications. With each case, the team finally gains more experience for the further performance of more complex total hip arthroplasty through the DAA with the main objective of superior clinical results for the patient.
Aims
This study aimed to use intraoperative free electromyography to examine how the placement of a retractor at different positions along the anterior acetabular wall may affect the femoral nerve during total hip arthroplasty (THA) when undertaken using the direct anterior approach (THA-DAA).
Methods
Intraoperative free electromyography was performed during primary THA-DAA in 82 patients (94 hips). The highest position of the anterior acetabular wall was defined as the “12 o’clock” position (middle position) when the patient was in supine position. After exposure of the acetabulum, a retractor was sequentially placed at the ten, 11, 12, one, and two o’clock positions (right hip; from superior to inferior positions). Action potentials in the femoral nerve were monitored with each placement, and the incidence of positive reactions (defined as explosive, frequent, or continuous action potentials, indicating that the nerve was being compressed) were recorded as the primary outcome. Secondary outcomes included the incidence of positive reactions caused by removing the femoral head, and by placing a retractor during femoral exposure; and the incidence of femoral nerve palsy, as detected using manual testing of the strength of the quadriceps muscle.
Results
Positive reactions were significantly less frequent when the retractor was placed at the ten (15/94; 16.0%), 11 (12/94; 12.8%), or 12 o’clock positions (19/94; 20.2%), than at the one (37/94; 39.4%) or two o’clock positions (39/94; 41.5%) (p < 0.050). Positive reactions also occurred when the femoral head was removed (28/94; 29.8%), and when a retractor was placed around the proximal femur (34/94; 36.2%) or medial femur (27/94; 28.7%) during femoral exposure. After surgery, no patient had reduced strength in the quadriceps muscle.
Conclusion
Placing the anterior acetabular retractor at the one or two o’clock positions (right hip; inferior positions) during THA-DAA can increase the rate of electromyographic signal changes in the femoral nerve. Thus, placing a retractor in these positions may increased the risk of the development of a femoral nerve palsy. Cite this article: Bone Joint J 2022;104-B(2):193–199.
The incidence of nerve injury ranges from 0.17% to 3.7% during primary hip arthroplasty and is reported to be as high as 7.5% in revision surgery. It is an often serious complication arising from this frequently performed surgical procedure. There is a wide range of severity of nerve injury, with more severe injuries having a notable impact on the patient’s overall functional outcome. In describing the pathophysiology and risk factors for nerve injury during total hip arthroplasty, the authors will delineate preventative measures and appropriate steps for referral and subsequent management.
Iatrogenic nerve injury is a rare but potentially devastating complication in total joint arthroplasty of the hip and the knee. Multiple previous studies have evaluated the incidence, mechanisms of injury, recovery, and potential treatments for this complication. Injury in total hip arthroplasty generally involves direct injury of sensory nerves from the incision, direct or traction injury of during exposure, or limb lengthening. Injury in total knee arthroplasty generally involves direct injury of sensory nerves from incision, injury due to errant placement of retractors, during balancing, or from traction because of deformity correction. Treatment of iatrogenic nerve injuries has ranged from observation, intraoperative prevention by nerve monitoring, limb shortening postoperatively, medications, and decompression. The orthopaedic surgeon should be versed in these etiologies to advise their patients on the incidence of injury, to prevent occurrence by understanding risky intraoperative maneuvers, and to select appropriate interventions when nerve injuries occur.
* While no single approach for total hip arthroplasty (THA) has been proven to be superior to others in terms of patient outcomes, the direct anterior approach (DAA) is becoming increasingly popular.
* All of the described techniques for THA carry a small risk of nerve injury.
* Identifying risk factors for nerve injury and mitigating these risks where feasible are imperative in order to reduce the incidence of this complication with any approach for THA.
The popularity of the direct anterior approach for total hip arthroplasty (THA) has dramatically increased in recent years. Many patients request this muscle sparing approach for the theorized benefits of quicker recovery and reduced post-operative pain. Femoral nerve injury is a rare, yet serious complication following the anterior approach for THA. During the 7-year period from 2008 to 2016, 1756 patients underwent primary THA with a direct anterior approach by a single senior surgeon for end-stage osteoarthritis. Six (0.34%) of these patients had a post-operative femoral nerve palsy. We aim to discuss anatomic considerations, risk factors, and a timeline of severity and recovery for femoral nerve palsy following direct anterior THA in six patients.
Retractor placement is a leading cause of intraoperative nerve injury during total hip replacement (THR) surgery. The sciatic nerve, femoral nerve, and superior gluteal nerve are most commonly affected. This study aimed to identify the distances from bony landmarks in the hip to the adjacent nerves on magnetic resonance imaging (MRI) and the associations between anatomical factors and these distances that would guide the placement of retractors during THR surgery, in order to minimize the risk of nerve injury.
We reviewed hip MRIs of 263 adults and recorded the distances from (1) the anterior acetabular rim to the femoral nerve; (2) the superior acetabular rim to the superior gluteal nerve; (3) the posterior acetabular rim to the sciatic nerve; and (4) the greater trochanter to the sciatic nerve. The effects of anatomical factors (i.e., gender, age, body height, body mass index (BMI), pelvic width, and acetabular version and morphology) on these distances were analyzed.
Distances from bony landmarks to adjacent nerves (in cm) were 2.06 ± 0.44, 2.23 ± 0.28, 1.94 ± 0.81, and 4.83 ± 0.26 for the anterior acetabular rim, superior acetabular rim, posterior acetabular rim, and greater trochanter, respectively, and were shorter in women than in men (P < 0.001). Multivariate analysis identified body height as the most influential factor (P < 0.001). Linear regression demonstrated a strong positive linear correlation between body height and these distances (Pearson’s r = 0.808, 0.823, 0.818, and 0.792, respectively (P < 0.001)).
The distances from bony landmarks to adjacent nerves provide useful information for placing retractors without causing nerve injury during THR surgery. Shorter patients will have shorter distances from bony landmarks to adjacent nerves, prompting more careful placement of retractors.
Background:
During the direct anterior approach for total hip arthroplasty, a retractor is placed on the anterior wall of the acetabulum to retract the iliopsoas muscle. This step with the retractor has been reported to put the patient at risk for femoral nerve damage. The present study aimed to clarify the effects of the anterior acetabular retractor on the status of the femoral nerve during the direct anterior approach on the basis of transcranial motor-evoked potential (MEP) analysis.
Methods:
Between July 2016 and February 2017, 22 patients underwent primary total hip arthroplasty via the direct anterior approach with MEP analysis. The integrity of the femoral nerve was tested at 3 time points: preoperatively, as a control (first period); just after retractor placement on the anterior wall of the acetabulum (second period); and after the procedure (third period). The association between operative time and femoral nerve status was examined. Postoperative femoral nerve damage was determined by the presence of causalgia and the results of a manual muscle test (MMT) for strength of knee extension.
Results:
The mean amplitude of the femoral nerve was significantly reduced, from 100% in the first period to 54% (range, 5% to 100%) in the second period (p < 0.01), but then significantly improved to 77% (range, 20% to 100%) in the third period (p < 0.01). In 17 (77%) of the 22 patients, the amplitude of the femoral nerve in the second period was reduced, while only 5 patients (23%) showed no reduction. The mean operative time was 83 minutes (range, 63 to 104 minutes), and no significant correlation was observed between operative time and improvement of femoral nerve status between the second and third periods (p = 0.83 and r = -0.05). All 22 patients had a postoperative MMT grade of 5 for knee extension without causalgia of the femoral nerve.
Conclusions:
On the basis of the MEP analysis, 17 (77%) of the 22 patients showed a significant reduction of the femoral nerve amplitude despite careful placement of the retractor on the anterior wall of the acetabulum. Although this reduction appears reversible, placement of an anterior retractor should be performed with careful attention to the femoral nerve.
Level of evidence:
Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.
Abstract
Background
Femoral nerve palsy (FNP) is a relatively uncommon complication following total hip arthroplasty. There is little recent literature regarding the incidence of FNP and the natural course of recovery.
Methods
Using our institutional database, we identified postoperative FNPs from 17,350 consecutive primary total hip arthroplasties (THA) performed from 2011-2016. Hip exposures were performed using a direct lateral (modified Hardinge), direct anterior (Smith-Peterson), anterolateral (Watson-Jones), or posterolateral (Southern or Moore) approach. Patients with FNP were contacted to provide a subjective assessment of convalescence and underwent objective muscle testing to determine the extent of motor recovery.
Results
The overall incidence of FNP was 0.21% after total hip arthroplasty, with the incidence 14.8-fold higher in patients undergoing anterior hip surgery using either a direct anterior (0.40%) or anterolateral (0.64%) approach. Significant recovery from FNP did not commence for a majority of patients until greater than 6 months postoperatively. Motor weakness had resolved in 75% of patients at 33.3 months, with remaining patients suffering from mild residual weakness that typically did not necessitate an assistive walking device or a knee brace. Nearly all patients had improved sensory manifestations, but such symptoms had completely resolved in less than 20% of patients.
Conclusion
FNP after hip surgery remains relatively uncommon, but may increase with a growing interest in anterior THA exposures. A near complete recovery with only mild motor deficits can be expected for a majority of patients in less than 2 years, though sensory symptoms may persist.
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.
A systematic review of the literature on clinical outcomes following direct anterior approach (DAA) hip arthroplasty was performed. An aggregated 11,810 hip procedures were analyzed for intraoperative and early postoperative complications. The most common complication following DAA hip arthroplasty was nerve dysfunction (2.8%) followed by intraoperative fractures (2.3%). Postoperative dislocation, wound complications, and revision THA within the first 12months were reported in 1.2% of cases. Thus, while DAA hip arthroplasty can be successfully performed, it is not without complications. Without definitive evidence of clinical superiority, surgeons considering switching to DAA should benchmark their personal complication rates against published reports.
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Neurovascular injury during total hip arthroplasty (THA) may result in considerable morbidity or mortality. The most common cause of intraoperative neurovascular injury during THA is retractor compression. Our aims were to: 1) determine proximity of common acetabular retractor positions during THA to adjacent neurovascular structures; and 2) determine effect of patient gender on these measurements. Retractor to neurovascular structure distances were measured on 32 preoperative computed tomography images and 16 cadavers. Our data suggest the anterior inferior iliac spine is the safest anterior acetabular retractor position. With inferior progression along the anterior wall, the distance to the femoral neurovascular bundle decreases. Due to its proximity to the sciatic nerve, the position of the posterior retractor should be monitored during acetabular preparation, particularly in women.
Objectives:
Acetabular retractors have been implicated in damage to the femoral and obturator nerves during total hip replacement. The aim of this study was to determine the anatomical relationship between retractor placement and these nerves.
Methods:
A posterior approach to the hip was carried out in six fresh cadaveric half pelves. Large Hohmann acetabular retractors were placed anteriorly, over the acetabular lip, and inferiorly, and their relationship to the femoral and obturator nerves was examined.
Results:
If contact with bone was not maintained during retractor placement, the tip of the anterior retractor had the potential to compress the femoral nerve by passing superficial to the iliopsoas. If pressure was removed from the anterior retractor, the tip pivoted on the anterior acetabular lip, and passed superficial to the iliopsoas, overlying and compressing the femoral nerve, when pressure was reapplied. The inferior retractor pierced the obturator membrane in all specimens medial to the obturator nerve, with subsequent retraction causing the tip to move laterally, making contact with the nerve.
Conclusion:
Iliopsoas can only offer protection to the femoral nerve if the retractor passes deep to the muscle bulk. The anterior retractor should be reinserted if pressure is removed intra-operatively. Vigorous movement of the inferior retractor should be avoided. Cite this article: Bone Joint Res 2014;3:212-6.
A total of 20 hip joints of 10 non-fixed corpses were examined within 48 h of death to measure the pressure below the inguinal ligament simulating the surgical conditions during total hip arthroplasty. The purpose of this study was to assess the influence of various leg positions and insertion techniques of retractors during the surgical procedure for total hip replacement in order to detect supposed causes for indirect pressure injuries of the femoral nerve. The obtained results verified no increase of pressure in the inguinal canal which could explain an indirect injury of the femoral nerve. If the retractor is inserted correctly at the anterior acetabular rim, the pressure in the lacuna musculorum can even be reduced, and furthermore, the femoral nerve is protected by the iliopsoas muscle. Femoral nerve lesions which have been published so far can only be explained by an incorrect use of instruments or implants (e.g., screws, cement, acetabular cup) or an extreme postoperative leg length discrepancy.
Femoral neuropathy is an uncommon yet debilitating complication of total hip arthroplasty (THA). Over a 1-year period, in 440 consecutive THAs performed at Pennsylvania Hospital, 10 (2.3%) femoral neuropathies occurred. Among primary arthroplasties, all neuropathies were associated with the Hardinge anterolateral approach. A retrospective case review as well as a detailed anatomic cadaveric study highlighted the characteristics of the femoral nerve that make it susceptible to injury. In addition, a review of the existing literature on this subject was performed. Placement and management of acetabular retractors were the factors most commonly associated with injury of the femoral nerve. All affected patients had significant initial disability. However, full femoral nerve. All affected patients had significant initial disability. However, full functional recovery occurred within 1 postoperative year. Clear understanding and awareness of the anatomy of the femoral triangle as well as accurate placement of anterior acetabular retractors can minimize the incidence of this complication.
We reviewed the results of 3126 consecutive total hip replacements and identified postoperative neuropathy in the ipsilateral lower extremity after fifty-three (1.7 per cent) over-all and after 1.3 per cent of the primary arthroplasties. The prevalence was 5.2 per cent after the primary arthroplasties that had been done for congenital dislocation or dysplasia of the hip and 3.2 per cent after the revisions (all diagnoses). Thus, these two types of operations were risk factors (p less than 0.01). Limb-lengthening only partially accounted for the increased prevalence of neuropathy after these procedures. The sciatic nerve was involved in all but five extremities. The cause of the palsy was unclear or unknown in thirty (57 per cent) of the extremities. When the patients were last seen, at a minimum of one year and a maximum of sixteen and one-half years after the operation, seven extremities were normal neurologically, thirty-three had a mild neurological deficit, and thirteen had a major deficit. All patients who had complete recovery of neurological function had it by twenty-one months. Of thirty-six extremities that were evaluated at a minimum of twenty-four months after the operation, seven were neurologically normal, twenty-three had a mild persistent deficit, and six had a major persistent deficit. The ability to walk decreased for all patients who had a nerve palsy. The greatest disability was in the patients who had been forty-eight years old or less and had had a primary total hip replacement (p = 0.037). The prognosis for neurological recovery was related to the degree to which the nerve was damaged.(ABSTRACT TRUNCATED AT 250 WORDS)
• Five cases of arterial complications of total hip replacement, all of which can be explained on the basis of intraoperative injury, are reported, with diagrammatic analysis of the intraoperative mechanisms of injury involved. The injuries were manifested as hemorrhage, ischemia, or development of a pulsatile mass. Vascular structures affected include the external iliac, common femoral, medial femoral circumflex, and lateral femoral circumflex arteries. Arterial damage may result from retractor injury, thermal injury from methylmethacrylate, or direct penetration from polymer or gouging during acetabular preparation. An understanding of the mechanisms and location of arterial injury following hip replacement will aid the vascular surgeon in diagnosis, exposure, and repair of these injuries.
(Arch Surg 1981;116:345-349)
Nerve palsy is an uncommon but acknowledged complication of total hip replacement. The overall prevalence is approximately 1%. The sciatic nerve, or the peroneal division of the sciatic nerve, is involved in nearly 80% of cases. The risk of nerve palsy in association with total hip replacement is increased for female compared with male patients, with a diagnosis of developmental dysplasia, and with patients undergoing revision surgery. In the majority of cases, the origin of the palsy is unknown. Because peripheral nerves are sensitive to compression, unrecognized compression may play a role in these cases. The prognosis for neurologic recovery is related to the degree of nerve damage. Complete, or essentially complete, recovery occurs in approximately 41% and another 44% have only a mild deficit. Approximately 15% have a poor outcome characterized by weakness that limits ambulation and/or persistent dysesthesia. Patients with some motor function immediately after the operation and those who recover some motor function within approximately 2 weeks of surgery have a good prognosis for recovery. In general, recovery of femoral nerve palsies is more predictable than that of sciatic palsies.
Pressure changes around the femoral nerve were monitored throughout 10 consecutive primary total hip replacements to identify any surgical steps that might raise pressure around the nerve and be implicated in iatropathic palsy. The only notable variable was the patient himself/herself. The only step that consistently raised pressure around the nerve, sometimes to alarming levels, was use of a retractor sited on the anterior lip of the acetabulum. Pressure changes were modest in patients with an endomorphic body type suggesting relative protection from this injury by a thicker soft cushion.