Gluteal Nerve Damage Following Total Hip Arthroplasty A Prospective Analysis
J. J. A b i t b o l , M D , F R C S C , * D. G e n d r o n , M D , F R C P ( C ) , -t--l: C. A. L a u r i n , M D , F R C S C , + a n d M . A. B e a t t l i e u , M D , F R C P ( C ) §
Abstract: Injuries to the peroneal or tobial divisions of the sciatic nerve occur in approximately 0.7-7.6% of patients undergoing total hip arthroplasty. No prior studies ltave investigated the incidence of injury to the superior or inferior gluteal nerves during hip surgery. This study evaluates the incidence of injury to the superior and inferior gluteal nerves in 55 patients undergoing total hip arthroplasty using a newly devised EMG scoring system. Subclinical gluteal nerve injury was documented in over 77% of patients, whether a posterior or a lateral approach to the hip was used. Key words: electromyography (EMG), gluteal nerve, hip arthroplasty, nerve injury.
injury to the superior and inferior gluteal nerves following hip arthroplasty comparing two different surgical approaches.
Injuries to peripheral nerves occur in 0 . 7 - 7 . 6 % of patients undergoing total hip arthroplasty ( 1 - 6 ) . Prior electromyographic (EMG) studies have focused on injury to the sciatic nerve or its peroneal and tibial divisions. No authors, however, have investigated injuries to the superior and inferior gluteal nerves following hip arthroplasty. Cadaveric dissections of the hip performed by the authors through a lateral or posterior surgical approach have confirmed that these nerves may be stretched during the hip dislocation m a n e u v e r and/or soft-tissue retraction in the area of the femoral neck (unpublished data). This study was undertaken to d o c u m e n t the incidence of
Materials and Methods EMG studies were conducted on 55 patients before and after operation at regular intervals after hip arthroplasty using either a lateral or posterior approach to the hip. Forty-five patients u n d e r w e n t uncemented total hip arthroplasw through a modified lateral approach performed by the senior a u t h o r (C.A.L.). An anterior osteotomy of the greater trochanter was carried out in each case, reflecting the anterior portion of the gluteus medius and minimis muscles together with the bone. There were 27 w o m e n and 18 men with a mean age of 57 years (range, 2 4 - 8 3 years). Ten patients u n d e r w e n t total hip arthroplasty through a standard posterior ap-
* Front ttre Division of Orthopaedics and RehabiEtation, University of California at San Diego, San Diego, California. t Front the Montreal Neurological Institute, Montreal Canada. From McGill University, Montreal Canada. § Front the Division of Neurology, Ottawa General Hospital University of Ottawa, Ontario, Canada. Reprint requests: J. J. Abitbol, MD, FRCSC (H-894), Assistant Professor o.f Surgery, Division of Orthopaedics and Rehabilitation, University of California at San Didgo, 225 Dickinson Street, San Diego, CA 92103.
319
320
The Journal of Arthroplasty Vol. 5 No. 4 December 1990
Table 2. Classification of Limp
GLUTEUS MEDIUS
Grade
Criteria
1 2* 3 4
Minimal limp Obvious limp; correctable Obvious limp; uncorrectable Severe limp
* Corrected to grade 1 when patient encouraged to concentrate on gait.
GLI MI TENSOR FASCIA LATA
Fig. 1. Needle insertion sites for EMG evaluations (black dots). proach performed at the same institution by two different surgeons. There were 7 w o m e n and 3 men ~vith a m e a n age of 69 years (range, 5 9 - 8 9 ) . Eight patients u n d e r w e n t uncemented and 2 underwent cemented arthroplasties. EMG evaluations were carried out prospectively in a DISA 1500 System with a Delay Unit using a concentric electrode. In an effort to improve specificity of the EMG for neuronal damage and to distinguish these changes from operative trauma to Table 1. EMG Scoring System
Polyphasic potentials Category l
Score
Description
0 1
Normal Mild increase in polyphasic potential (l 5-30% of total number) Moderate Very severe (80% of potentials being polyphasic) Absence Mild (had to look hard for it) Moderate (easy to find) Total denervation Normal Full but neurogenic sounding Diminished and neurogenic Absent
2 3 Spontaneous activity Category 2
0 l
Recruitment Category 3
2 3 0 1 2 3
muscle, multiple needle insertion sites were chosen for each study (Fig. 1). Testing included the anterior and posterior gluteus medius and minimis, the superior and inferior tensor fascia lata, and the superior and inferior gluteus maximus muscles. To facilitate comparison and reporting of EMG data, a scoring system was devised (Table 1). EMG recordings were scored in three categories by a single investigator (D.G.). Category 1 included polyphasic motor units, suggesting chronic denervation and reinnervation. These were graded from 0 (normal) to 3 (representing severe abnormalities). Category 2 included fibrillation potentials and positive sharp waves suggesting active denervation. These were graded from 0 (totally absent) to 3 (representing marked activity). A third category evaluated muscle recruitment potential. This was graded from 0 (showing normal recruitment) to 3 (indicating no activity). The scores from each category were then added to give a final EMG score for each muscle tested: 0 represented a completely normal muscle, and 9 a totally denervated muscle. Patient gait was assessed before ~nd after operation by a blinded physical therapist. Limp was graded from normal gait (grade 1) to a severe limp (grade 4) (Table 2). Statistical analysis was performed using a Wilcoxon signed-rank test comparing the EMG scores between lateral and posterior approach at 6 weeks, 24 weeks, and 52 weeks after operation. Nonparametric regression analysis was performed to compare EMG changes to degree of limp. Lastly, limp was compared between groups before and after operation using the Mann-Whitney U-test. Significance was set at P --< .05.
Results Lateral Approach Table 3 lists the EMG scores for all patients undergoing a lateral approach to the hip. Preoperative scores were 0 for all muscle groups. At 6 post-
Gluteal Nerve Damage in THA
•
Abitbol et al.
321
T a b l e 3. Lateral Approach EMG Scores Muscle
Preoperative
6 Weeks
24 Weeks
52 Weeks
0 0 0 0 0 0 0 0
I. l 1.0 1.7 1.3 0.9 2.0 0.9 0.9
1.1 1.5 2.2 1.0 1.3 1.2 0.9 1.3
0.9 1.6 1.6 0.5 0.8 1.O 0.4 0.5
TFL: Superior TFL: Inferior G Min: Anterior G Min: Posterior G Med: Anterior G Med: Posterior G Max: Superior G Max: Inferior
Mean EMG scores for patients undergoing a lateral approach to the hip before and after operation. Individual scores are graded from 0 (normal) to 9 (complete denervation).
o p e r a t i v e weeks, 7 7 % of t h e hips h a d a b n o r m a l findings o n E M G studies i n m u s c l e s i n n e r v a t e d b y the inferior or suPerior gluteal nerves. This decreased to 3 9 % a n d 4 0 % at 52 weeks, respectively.
pared to scores after a posterior a p p r o a c h at e a c h f o l l o w - u p interval. No significant differences w e r e seen in EMG scores b e t w e e n the t w o a p p r o a c h e s . EMG recordings w e r e p r e d o m i n a n t l y of the categories 2 a n d 3 at 6 w e e k s after o p e r a t i o n , c h a n g i n g to m o s t l y category 1 at a n n u a l f o l l o w - u p e v a l u a t i o n following b o t h approaches. Preoperative l i m p e v a l u a t i o n s h o w e d n o signific a n t difference b e t w e e n the two g r o u p s (Table 5). At 6 m o n t h s , 56% of p a t i e n t s h a v i n g a lateral app r o a c h a n d 50% of p a t i e n t s h a v i n g a p o s t e r i o r app r o a c h h a d a grade 3 limp, versus 4 4 % a n d 50% w h o h a d a grade 2 limp, respectively. At 1 y e a r b o o t h groups i m p r o v e d , w i t h the posterior a p p r o a c h patients h a v i n g t e n d e n c y t o w a r d less of a l i m p ; h o w ever, this was n o t statistically significant. No correl a t i o n was f o u n d b e t w e e n the degree of l i m p a n d the EMG scores i n either group.
Posterior Approach EMG scores after a posterior a p p r o a c h to the hip are listed i n Table 4. All scores w e r e 0 ( n o r m a l ) before o p e r a t i o n . At 6 weeks, 8 8 % of hips had a b n o r m a l E M G studies i n inferior gluteal i n n e r v a t e d m u s cles a n d 77% i n s u p e r i o r gluteal i n n e r v a t e d muscles. This decreased to 33% a n d 35% at 52 weeks, respectively. E M G scores after a lateral a p p r o a c h were corn-
T a b l e 4. Posterior Approach EMG Scores Muscle
Preoperative
6 Weeks
24 Weeks
52 Weeks
0 0 0 0 0 0 0 0
2.3 1.9 0.9 1.4 1.3 1.3 2.1 1.5
3.0 3.3 1.3 3.0 1.3 2.3 2.0 1.3
0.9 1.1 0.4 0.3 0.9 1.0 1.1 0.4
TFL: Superior TFL: Inferior G Min: Anterior G Min: Posterior G Med: Anterior G Med: Posterior G Max: Superior G Max: Inferior
Mean EMG scores for patients undergoing a posterior approach to the hip before and after operation. Individual scores are graded from 0 (normal) to 9 (complete denervation).
T a b l e 5. Limp Lateral Approach Preoperative 24 Weeks 52 Weeks (%) (%) (%) Grade I Grade 2 Grade 3 Grade 4
0 17 64 19
0 44
56 0
17 57 26 0
Posterior Approach Preoperative 24 Weeks 52 Weeks (%) (%) (%) 0 20 60 20
0 50 50 0
30 50 20 0
322
The Journal of Arthroplasty Vol. 5 No. 4 December 1990
Discussion Evidence of clinical nerve dysfunction after total hip arthroplasty has been reported to be between 0 . 7 - 3 . 0 % in primary surgery and 2 . 9 - 7 . 6 % in revision surgery ( i - 6 ) . Several mechanisms of nerve injury in hip surgery have been proposed. Stone et al., in a study monitoring sciatic nerve function during total hip arthroplasty using somatosensoryevoked potentials, demonstrated nerve compromise during nerve retraction or over-lengthening of a limb (excessive tension) (7). Difficulties have arisen in quantifying the extent of nerve injury. Weber conducted a prospective study of 30 hip arthroplasties performed through a transtrochanteric approach. After operation, 21 of 30 extremities demonstrated EMG evidence of sciatic, obturator, or femoral nerve dysfunction. Nineteen of these injuries were subclinical (8). No prior studies have been performed on the superior or inferior gluteal nerves following hip arthroplasty. The gluteal nerves inner'care the tensor fascia lata and the gluteus maximus, medius, and minimis muscles. Injury to these nerves, by whatever mechanism, would help explain postoperative gait abnormalities. Our results showed similar EMG injury patterns in .the superior and inferior gluteal nerve distributions w h e n comparing the lateral to posterior approaches. At 6 postoperative weeks, 7 7 - 8 8 % of hips had abnormal EMG findings in the muscles innervated by these nerves. EMG scores were all between 0 - 3 . 3 / 9.0, and there was no evidence for significant denervation of either gluteal nerves. Improvement was universal by 1 year. The absence of correlation between degree of limp and the EMG score, regardless
of the surgical approach, is likely related to the multifactorial etiology of limp. In summary, this study documents subclinical nerve injury to the superior and inferior gluteal nerves in a majority of total hip arthroplasty pat i e n t s - r e g a r d l e s s of the surgical approach used. Denervative changes seen on EMGs could be partly explained by surgical muscle trauma. These EMG findings did not appear to alter the patient's rehabilitation and the success of the total hip arthroplasty+
References 1. Amstutz HC, Ma SM, Jinnah RH, Mai L: Revision of aseptic loose total hip arthroplasties. Clin Orthop 170:21, 1982 2. Buchholz HW, Noack G: Results of the total hip prosthesis design "'St. George." Clin Orthop 95:201, 1973 3. Charnley J, Cupic Z: The nine and ten year results of the low friction anhroplasty of the hip. Clin Onhop 95:9, 1973 4. Johanson NA, Pellicci PM, Tsairis P, Salvati EA: Nerve injury in total hip arthroplasty. Clin Orthop 179:214, 1983 5. Lazansky MG: Complications revisited: the debit side of total hip replacement. Clin Onhop 95:96, 1973 6. Solheim LF, Hagen R: Femoral and sciatic neuropathies after total hip arthroplasty. Acta Orthop Scand 51:531, 1980 7. Stone RG, Weeks LE, Hajdu M, Stinchfield FE: Evaluation of sciatic nerve compromise during total hip arthroplasty. Clin Orthop 201:26, 1985 8. Weber ER, Daube JR, Coventry MB: Peripheral neuropathies associated with total hip arthroplasty. J Bone Joint Surg 58A:66, 1976
J. J. A b i t b o l , M D , F R C S C , * D. G e n d r o n , M D , F R C P ( C ) , -t--l: C. A. L a u r i n , M D , F R C S C , + a n d M . A. B e a t t l i e u , M D , F R C P ( C ) §
Abstract: Injuries to the peroneal or tobial divisions of the sciatic nerve occur in approximately 0.7-7.6% of patients undergoing total hip arthroplasty. No prior studies ltave investigated the incidence of injury to the superior or inferior gluteal nerves during hip surgery. This study evaluates the incidence of injury to the superior and inferior gluteal nerves in 55 patients undergoing total hip arthroplasty using a newly devised EMG scoring system. Subclinical gluteal nerve injury was documented in over 77% of patients, whether a posterior or a lateral approach to the hip was used. Key words: electromyography (EMG), gluteal nerve, hip arthroplasty, nerve injury.
injury to the superior and inferior gluteal nerves following hip arthroplasty comparing two different surgical approaches.
Injuries to peripheral nerves occur in 0 . 7 - 7 . 6 % of patients undergoing total hip arthroplasty ( 1 - 6 ) . Prior electromyographic (EMG) studies have focused on injury to the sciatic nerve or its peroneal and tibial divisions. No authors, however, have investigated injuries to the superior and inferior gluteal nerves following hip arthroplasty. Cadaveric dissections of the hip performed by the authors through a lateral or posterior surgical approach have confirmed that these nerves may be stretched during the hip dislocation m a n e u v e r and/or soft-tissue retraction in the area of the femoral neck (unpublished data). This study was undertaken to d o c u m e n t the incidence of
Materials and Methods EMG studies were conducted on 55 patients before and after operation at regular intervals after hip arthroplasty using either a lateral or posterior approach to the hip. Forty-five patients u n d e r w e n t uncemented total hip arthroplasw through a modified lateral approach performed by the senior a u t h o r (C.A.L.). An anterior osteotomy of the greater trochanter was carried out in each case, reflecting the anterior portion of the gluteus medius and minimis muscles together with the bone. There were 27 w o m e n and 18 men with a mean age of 57 years (range, 2 4 - 8 3 years). Ten patients u n d e r w e n t total hip arthroplasty through a standard posterior ap-
* Front ttre Division of Orthopaedics and RehabiEtation, University of California at San Diego, San Diego, California. t Front the Montreal Neurological Institute, Montreal Canada. From McGill University, Montreal Canada. § Front the Division of Neurology, Ottawa General Hospital University of Ottawa, Ontario, Canada. Reprint requests: J. J. Abitbol, MD, FRCSC (H-894), Assistant Professor o.f Surgery, Division of Orthopaedics and Rehabilitation, University of California at San Didgo, 225 Dickinson Street, San Diego, CA 92103.
319
320
The Journal of Arthroplasty Vol. 5 No. 4 December 1990
Table 2. Classification of Limp
GLUTEUS MEDIUS
Grade
Criteria
1 2* 3 4
Minimal limp Obvious limp; correctable Obvious limp; uncorrectable Severe limp
* Corrected to grade 1 when patient encouraged to concentrate on gait.
GLI MI TENSOR FASCIA LATA
Fig. 1. Needle insertion sites for EMG evaluations (black dots). proach performed at the same institution by two different surgeons. There were 7 w o m e n and 3 men ~vith a m e a n age of 69 years (range, 5 9 - 8 9 ) . Eight patients u n d e r w e n t uncemented and 2 underwent cemented arthroplasties. EMG evaluations were carried out prospectively in a DISA 1500 System with a Delay Unit using a concentric electrode. In an effort to improve specificity of the EMG for neuronal damage and to distinguish these changes from operative trauma to Table 1. EMG Scoring System
Polyphasic potentials Category l
Score
Description
0 1
Normal Mild increase in polyphasic potential (l 5-30% of total number) Moderate Very severe (80% of potentials being polyphasic) Absence Mild (had to look hard for it) Moderate (easy to find) Total denervation Normal Full but neurogenic sounding Diminished and neurogenic Absent
2 3 Spontaneous activity Category 2
0 l
Recruitment Category 3
2 3 0 1 2 3
muscle, multiple needle insertion sites were chosen for each study (Fig. 1). Testing included the anterior and posterior gluteus medius and minimis, the superior and inferior tensor fascia lata, and the superior and inferior gluteus maximus muscles. To facilitate comparison and reporting of EMG data, a scoring system was devised (Table 1). EMG recordings were scored in three categories by a single investigator (D.G.). Category 1 included polyphasic motor units, suggesting chronic denervation and reinnervation. These were graded from 0 (normal) to 3 (representing severe abnormalities). Category 2 included fibrillation potentials and positive sharp waves suggesting active denervation. These were graded from 0 (totally absent) to 3 (representing marked activity). A third category evaluated muscle recruitment potential. This was graded from 0 (showing normal recruitment) to 3 (indicating no activity). The scores from each category were then added to give a final EMG score for each muscle tested: 0 represented a completely normal muscle, and 9 a totally denervated muscle. Patient gait was assessed before ~nd after operation by a blinded physical therapist. Limp was graded from normal gait (grade 1) to a severe limp (grade 4) (Table 2). Statistical analysis was performed using a Wilcoxon signed-rank test comparing the EMG scores between lateral and posterior approach at 6 weeks, 24 weeks, and 52 weeks after operation. Nonparametric regression analysis was performed to compare EMG changes to degree of limp. Lastly, limp was compared between groups before and after operation using the Mann-Whitney U-test. Significance was set at P --< .05.
Results Lateral Approach Table 3 lists the EMG scores for all patients undergoing a lateral approach to the hip. Preoperative scores were 0 for all muscle groups. At 6 post-
Gluteal Nerve Damage in THA
•
Abitbol et al.
321
T a b l e 3. Lateral Approach EMG Scores Muscle
Preoperative
6 Weeks
24 Weeks
52 Weeks
0 0 0 0 0 0 0 0
I. l 1.0 1.7 1.3 0.9 2.0 0.9 0.9
1.1 1.5 2.2 1.0 1.3 1.2 0.9 1.3
0.9 1.6 1.6 0.5 0.8 1.O 0.4 0.5
TFL: Superior TFL: Inferior G Min: Anterior G Min: Posterior G Med: Anterior G Med: Posterior G Max: Superior G Max: Inferior
Mean EMG scores for patients undergoing a lateral approach to the hip before and after operation. Individual scores are graded from 0 (normal) to 9 (complete denervation).
o p e r a t i v e weeks, 7 7 % of t h e hips h a d a b n o r m a l findings o n E M G studies i n m u s c l e s i n n e r v a t e d b y the inferior or suPerior gluteal nerves. This decreased to 3 9 % a n d 4 0 % at 52 weeks, respectively.
pared to scores after a posterior a p p r o a c h at e a c h f o l l o w - u p interval. No significant differences w e r e seen in EMG scores b e t w e e n the t w o a p p r o a c h e s . EMG recordings w e r e p r e d o m i n a n t l y of the categories 2 a n d 3 at 6 w e e k s after o p e r a t i o n , c h a n g i n g to m o s t l y category 1 at a n n u a l f o l l o w - u p e v a l u a t i o n following b o t h approaches. Preoperative l i m p e v a l u a t i o n s h o w e d n o signific a n t difference b e t w e e n the two g r o u p s (Table 5). At 6 m o n t h s , 56% of p a t i e n t s h a v i n g a lateral app r o a c h a n d 50% of p a t i e n t s h a v i n g a p o s t e r i o r app r o a c h h a d a grade 3 limp, versus 4 4 % a n d 50% w h o h a d a grade 2 limp, respectively. At 1 y e a r b o o t h groups i m p r o v e d , w i t h the posterior a p p r o a c h patients h a v i n g t e n d e n c y t o w a r d less of a l i m p ; h o w ever, this was n o t statistically significant. No correl a t i o n was f o u n d b e t w e e n the degree of l i m p a n d the EMG scores i n either group.
Posterior Approach EMG scores after a posterior a p p r o a c h to the hip are listed i n Table 4. All scores w e r e 0 ( n o r m a l ) before o p e r a t i o n . At 6 weeks, 8 8 % of hips had a b n o r m a l E M G studies i n inferior gluteal i n n e r v a t e d m u s cles a n d 77% i n s u p e r i o r gluteal i n n e r v a t e d muscles. This decreased to 33% a n d 35% at 52 weeks, respectively. E M G scores after a lateral a p p r o a c h were corn-
T a b l e 4. Posterior Approach EMG Scores Muscle
Preoperative
6 Weeks
24 Weeks
52 Weeks
0 0 0 0 0 0 0 0
2.3 1.9 0.9 1.4 1.3 1.3 2.1 1.5
3.0 3.3 1.3 3.0 1.3 2.3 2.0 1.3
0.9 1.1 0.4 0.3 0.9 1.0 1.1 0.4
TFL: Superior TFL: Inferior G Min: Anterior G Min: Posterior G Med: Anterior G Med: Posterior G Max: Superior G Max: Inferior
Mean EMG scores for patients undergoing a posterior approach to the hip before and after operation. Individual scores are graded from 0 (normal) to 9 (complete denervation).
T a b l e 5. Limp Lateral Approach Preoperative 24 Weeks 52 Weeks (%) (%) (%) Grade I Grade 2 Grade 3 Grade 4
0 17 64 19
0 44
56 0
17 57 26 0
Posterior Approach Preoperative 24 Weeks 52 Weeks (%) (%) (%) 0 20 60 20
0 50 50 0
30 50 20 0
322
The Journal of Arthroplasty Vol. 5 No. 4 December 1990
Discussion Evidence of clinical nerve dysfunction after total hip arthroplasty has been reported to be between 0 . 7 - 3 . 0 % in primary surgery and 2 . 9 - 7 . 6 % in revision surgery ( i - 6 ) . Several mechanisms of nerve injury in hip surgery have been proposed. Stone et al., in a study monitoring sciatic nerve function during total hip arthroplasty using somatosensoryevoked potentials, demonstrated nerve compromise during nerve retraction or over-lengthening of a limb (excessive tension) (7). Difficulties have arisen in quantifying the extent of nerve injury. Weber conducted a prospective study of 30 hip arthroplasties performed through a transtrochanteric approach. After operation, 21 of 30 extremities demonstrated EMG evidence of sciatic, obturator, or femoral nerve dysfunction. Nineteen of these injuries were subclinical (8). No prior studies have been performed on the superior or inferior gluteal nerves following hip arthroplasty. The gluteal nerves inner'care the tensor fascia lata and the gluteus maximus, medius, and minimis muscles. Injury to these nerves, by whatever mechanism, would help explain postoperative gait abnormalities. Our results showed similar EMG injury patterns in .the superior and inferior gluteal nerve distributions w h e n comparing the lateral to posterior approaches. At 6 postoperative weeks, 7 7 - 8 8 % of hips had abnormal EMG findings in the muscles innervated by these nerves. EMG scores were all between 0 - 3 . 3 / 9.0, and there was no evidence for significant denervation of either gluteal nerves. Improvement was universal by 1 year. The absence of correlation between degree of limp and the EMG score, regardless
of the surgical approach, is likely related to the multifactorial etiology of limp. In summary, this study documents subclinical nerve injury to the superior and inferior gluteal nerves in a majority of total hip arthroplasty pat i e n t s - r e g a r d l e s s of the surgical approach used. Denervative changes seen on EMGs could be partly explained by surgical muscle trauma. These EMG findings did not appear to alter the patient's rehabilitation and the success of the total hip arthroplasty+
References 1. Amstutz HC, Ma SM, Jinnah RH, Mai L: Revision of aseptic loose total hip arthroplasties. Clin Orthop 170:21, 1982 2. Buchholz HW, Noack G: Results of the total hip prosthesis design "'St. George." Clin Orthop 95:201, 1973 3. Charnley J, Cupic Z: The nine and ten year results of the low friction anhroplasty of the hip. Clin Onhop 95:9, 1973 4. Johanson NA, Pellicci PM, Tsairis P, Salvati EA: Nerve injury in total hip arthroplasty. Clin Orthop 179:214, 1983 5. Lazansky MG: Complications revisited: the debit side of total hip replacement. Clin Onhop 95:96, 1973 6. Solheim LF, Hagen R: Femoral and sciatic neuropathies after total hip arthroplasty. Acta Orthop Scand 51:531, 1980 7. Stone RG, Weeks LE, Hajdu M, Stinchfield FE: Evaluation of sciatic nerve compromise during total hip arthroplasty. Clin Orthop 201:26, 1985 8. Weber ER, Daube JR, Coventry MB: Peripheral neuropathies associated with total hip arthroplasty. J Bone Joint Surg 58A:66, 1976
