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Results of the Sugioka transtrochanteric rotational osteotomy for osteonecrosis: Frequency and role of a defect of the quadratus femoris muscle in osteonecrosis progression
Orthopaedics & Traumatology: Surgery & Research 102 (2016) 387–390
Available online at
ScienceDirect www.sciencedirect.com
Original article
Results of the Sugioka transtrochanteric rotational osteotomy for osteonecrosis: Frequency and role of a defect of the quadratus femoris muscle in osteonecrosis progression T. Yamamoto ∗ , G. Motomura , K. Karasuyama , Y. Nakashima , T. Doi , Y. Iwamoto Department of Orthopaedic Surgery, Graduate School of Medical Sciences, Kyushu University, 3-1-1 Maidashi, Higashi-ku, 812-8582 Fukuoka, Japan
a r t i c l e
i n f o
Article history: Received 17 July 2015 Accepted 19 January 2016 Keywords: Osteonecrosis Femoral head Quadratus femoris Rotational osteotomy
a b s t r a c t Background: During transtrochanteric rotational osteotomy (RO), it is important to preserve the posterior column artery (PCA), which is generally located in the adipose tissue underneath the quadratus femoris muscle (QF). If there is a defect in the QF, the risk of injuring the PCA, subsequently resulting in total necrosis of the femoral head, may increase. Therefore, we investigated: (1) the frequency of defects of the QF at the time of RO, and (2) clinical outcome of RO based upon a defect of the QF. Hypothesis: The presence of defects of the QF at the time of RO could be detected pre-operatively by magnetic resonance imaging. Methods: RO was performed in 124 hips between 2001 and 2010. In all, 95 of the hips were in male patients and 29 in female patients. The mean age was 45.4 years (range: 11–61 years) at the time of surgery and MRI was performed before RO in all cases. We retrospectively evaluated the progression of a collapse through 3 years after RO. Results: MRI showed a defect in the QF in four hips (3.2%) (2 males, 2 females), all of which were confirmed intra-operatively. Among the four patients, one (25%) underwent total hip arthroplasty because of varus deformity of the osteotomy site due to total necrosis of the femoral head 1 year after RO. The 120 hips with a normal QF showed no evidence of total necrosis or progression of necrosis of the femoral head, indicating that the presence of defects of the QF may increase the risk of poor survivorship of this procedure. Conclusions: Defects of the QF have been reported to occur in 1–2% of all patients, whereas in our study the incidence in ON was approximately 3%. In ON patients with QF defects, pre-operative MRI evaluation of the QF appears to be important when planning RO, followed by a carefully performed surgical procedure. Level of evidence: IV; retrospective case series without control group. © 2016 Elsevier Masson SAS. All rights reserved.
1. Introduction Once subchondral collapse occurs in a patient with osteonecrosis (ON) of the femoral head, surgical treatment is necessary to relieve the pain and to obtain good hip function [1,2]. First developed by Sugioka in 1978 [3], transtrochanteric rotational osteotomy (RO) is a joint-preserving procedure used to treat ON. The procedure involves transposing an intact area to a weightbearing portion of the joint, resulting in transfer of the necrotic area to a non-weight-bearing area. The survival rate has been reported to be around 80%, while less than 20% of survival rate has also been reported, indicating that this procedure is technically demanding [4–8]. One of the most important aspects in performing RO
∗ Corresponding author. Tel.: +81 92 642 5487; fax: +81 92 642 5507. E-mail address: [email protected] (T. Yamamoto). http://dx.doi.org/10.1016/j.otsr.2016.01.017 1877-0568/© 2016 Elsevier Masson SAS. All rights reserved.
is to preserve the posterior column artery (PCA), a branch of the medial femoral circumflex artery, which supplies nutrients to the femoral head [9,10]. The PCA is generally located in the adipose tissue underneath the quadratus femoris muscle (QF), which is a flat, quadrilateral muscle between the gemellus inferior and the proximal margin of the adductor magnus. In order to expose the obturator externus, minimum release of QF is recommended, but if the QF is absent, the adipose tissue is directly exposed, which may increase the risk of injuring the PCA during the procedure, eventually resulting in total necrosis of the femoral head. The QF is thus an important anatomical signpost for performing RO safely. However the anatomical variations of the QF muscle are not accurately known. In addition, there is no information whether the presence of defects of the QF at the time of RO influences the survivorship of this procedure. Therefore we investigated the frequency of QF defects at the time of RO in ON patients and also assessed their influence on clinical outcomes of RO. The goals of
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T. Yamamoto et al. / Orthopaedics & Traumatology: Surgery & Research 102 (2016) 387–390
Table 1 Clinical findings of the 4 patients with a defect of the quadratus femoris muscle. Patient number
Gender
Age
Etiology
Defect side
Necrosis side
Pre-operative stage and type
Procedure
Total necrosis of the femoral head (months)
1 2 3 4
Female Male Female Male
47 49 36 29
Corticosteroids Alcohol Corticosteroids Alcohol
Bilateral Left Bilateral Left
Bilateral Left Bilateral Bilateral
Stage Stage Stage Stage
Lt. PRO Lt. ARO Lt. PRO Lt. ARO
– – – + (10 months)
3A, type 3B, type 3A, type 3B, type
C2 C2 C2 C2
ARO: anterior rotational osteotomy; PRO: posterior rotational osteotomy; Rt.: right; Lt.: left.
the current study were to evaluate: (1) the frequency of defects of the QF at the time of RO, and (2) clinical outcome and survival of RO according to the presence of defects of the QF. Our hypothesis was that the presence of defects of the QF at the time of RO could be detected pre-operatively by magnetic resonance imaging.
2. Patients and methods
for 5 weeks, after which gradual weight-bearing was permitted. Full weight-bearing was permitted after 6 months. 2.3. Methods of assessment We evaluated radiographic evidence of total necrosis of the femoral head 3 years after the procedure based on AP and frog lateral views of all 124 hips. QF defects were pre-operatively assessed on MRI and checked during surgery.
2.1. Patients The institutional review board at our university approved this study. Between 2001 and 2010, transtrochanteric RO was performed in 124 hips (95 in males, 29 in females) of 109 patients whose average age was 45.4 years (range: 11–61 years) at the time of surgery. (During the same period, prosthetic hip replacement was performed in 200 ON hips, transtrochanteric varus osteotomy in 34 ON hips, but core decompression was done in none of the ON cases in our hospital [11,12]). RO was indicated and performed in patients who: (1) had a necrotic area in the anterior or posterior portion of the femoral head; (2) had an intact healthy area in the anterior or posterior portion; and, most importantly, (3) were predicted to have a postoperative intact area ratio over 34% after the RO [3,4]. Cases who fulfilled these criteria have been reported to have a low risk of progression of a collapse [4]. Based on the Japanese Investigation Committee Classification System of ON, 77 hips were stage 3A, 43 stage 3B, and 4 stage 4 (3A: collapse less than 2 mm, 3B: collapse over 3 mm), and one hip was categorized as type B, 18 as type C1, and 105 as type C2 [13]. (According to the Ficat and Arlet classification, 121 hips were in stage III and 4 in stage IV, while 121 hips in ARCO stage 3, and 4 in ARCO stage 4.) The etiology of ON was idiopathic in 5 hips, alcohol abuse in 50, post-trauma in 9 (including 11-year-old girl with ON after slipped capital femoral epiphysis), and corticosteroid use in 60. The presence of a QF defect was mainly investigated in all 124 hips based on intra-operative findings. In addition, preoperative MRI was examined whether only high-signal adipose tissue is observed without any evidence of muscle structure.
2.4. Statistical methods The prevalence of total necrosis of the femoral head in patients with a QF defect and those with a normal QF were statistically assessed using Fisher’s exact test. Statistical differences were considered significant when P < 0.05. 3. Results The pre-operative MRI examinations revealed a QF defect in 4 of the 124 hips with ON (3.2%) (2 males, 2 females) (Table 1). The etiology of the ON was alcohol abuse-related in two patients and corticosteroid-related in the other two. All the four cases were categorized as type C2 according the Japanese Investigation Committee Classification System of ON. The QF defects were confirmed intraoperatively in all four patients and no false negative cases were found. Anterior RO was performed in two patients and posterior RO in two. One of the four (25%) patients with a QF defect showed varus deformity of the osteotomy site resulting from total necrosis of the femoral head 10 months after the RO, resulting in conversion to a hip prosthesis (Fig. 1). The other three patients showed no evidence of total necrosis of the femoral head 3 years after RO. On the other hand, among the 120 RO cases in which the QF was normal, no hips showed progression of a collapse caused by total necrosis of the originally intact area 3 years after RO. This incidence was lower than that for the patients with a QF defect (P = 0.0323). 4. Discussion
2.2. Methods The basic RO surgical procedure has remained unchanged since it was described by Sugioka [3]. Briefly, it includes three osteotomies: (1) osteotomy of the greater trochanter; (2) intertrochanteric osteotomy, which passes from superolateral to inferomedial on the anteroposterior (AP) view; and (3) an osteotomy that passes from the proximal flare of the lesser trochanter inferolaterally toward the inferomedial extent of the primary osteotomy. During these osteotomies, preservation of the PCA (located in adipose tissue underneath the QF) is the most important procedure, so minimum release of QF in order to expose the obturator externus is recommended. To obtain rigid fixation, the K-MAX Adjustable Angle Hip Screw (K-MAX AA Hip Screw; Japan Medical Materials, Osaka, Japan) as well as two screws are used. Postoperatively, the patients were not allowed to bear weight
A QF defect has been observed in 1–2% of general patients in anatomical studies [14,15]. In the present study, the rate was approximately 3% in patients with ON who underwent RO at our institution. In addition, one of four patients with a QF defect underwent total necrosis of the femoral head, whereas cases with normal QF anatomy showed no evidence of total necrosis. This relatively high rate of total necrosis may indicate that when the QF is not observed another type of operation (e.g., transtrochanteric varus osteotomy) should be considered, although the number with a defect of QF muscle was only 4 hips and a defect of QF itself may not have been the direct cause of total necrosis. If the RO is the only joint-preserving procedure that is deemed appropriate, it is necessary to verify the location of the PCA pre-operatively using MR angiography or CT angiography to confirm the location of the PCA. If the PCA is not observed in its normal location, RO is not indicated.
T. Yamamoto et al. / Orthopaedics & Traumatology: Surgery & Research 102 (2016) 387–390
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Fig. 1. A 29-year-old man with alcohol-related osteonecrosis; a: on A-P view, subchondral collapse more than 3 mm is seen on the left hip; b: on a frog lateral view, the posterior part of the femoral head is intact and anterior RO was indicated; c: the T1-weighted MRI axial view shows that the quadratus femoris muscle (QF) (circled) on the right side is normal (arrows). However, on the left side (circled), only high-signal adipose tissue is observed (arrowheads); d: intra-operatively, the QF was not observed, and only adipose tissue was seen (arrowheads). The other obturator muscles, including the piriformis, obturator internus, gemellus, and obturator externus, were normal. GT: greater trochanter; LT: lesser trochanter; GM: gluteus medius; PR: piriformis; GS: gemellus superior; GI: gemellus inferior; VL: vastus lateralis; e: RO was performed with care so as not to damage the PCA or the adipose tissue. Postoperative intact area ratio was obtained around 50%; f: however, bone scintigraphy performed 5 weeks after RO showed a cold spot throughout the femoral head, indicating that there was no blood supply to it. Ten months after RO, varus deformity of the osteotomy site followed by a penetration of screw due to total necrosis of the femoral head was observed (black bar in e and f), when the Harris Hip Score was 43 points. Progression of a collapse is also observed (arrow) at the lateral portion of the femoral head; g: on a frog lateral view, anterior part of the femoral head showed a collapse (arrow). The histological examination of the resected femoral head revealed total necrosis of the femoral head.
There are several limitations in this study. First, it is unknown whether a defect of QF muscle itself was a direct cause of total necrosis of the femoral head in this study. It may be possible that other unknown factors may have influenced on postoperative total necrosis. Secondly, we focused only on ON patients for whom RO was indicated. Further study that includes other type of osteotomy, prosthetic replacements and non-operative cases is necessary to evaluate the precise prevalence of a QF defect in osteonecrosis cases. Thirdly, the number of cases with a defect of QF muscle was only 4 cases. In this study, statistical analysis was made based on this small number of cases and more documented cases are necessary. Finally, the relation between a QF defect and variants of the
PCA could not be analyzed in this study. Imaging studies using MR angiography or CT angiography are necessary. The obturator externus, which is located closely adjacent to the adipose tissue containing the PCA, must be completely dissected during RO in order to obtain sufficient rotation [3]. Also, the release of QF is necessary to expose this obturator externus, which should be minimum not to injure the PCA. In patients with a QF defect, the adipose tissue containing PCA is directly exposed. These conditions may increase the risk of injury of the PCA during surgery. Several variants of the PCA have been reported in ON cases, including the observation that the PCA is fed by a branch of the internal iliac artery, not from the medial femoral circumflex artery [10,16].
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Because all of the soft tissue containing a branch of the internal iliac artery needs be circumferentially resected around the femoral neck during an RO, such an abnormality may cause total necrosis of the femoral head because of disruption of the blood supply, which may subsequently result in varus deformity of the osteotomy site due to total necrosis of the femoral head. One of the four patients in this study underwent total necrosis of the femoral head despite a carefully performed procedure to prevent damage to the PCA and the medial femoral circumflex artery, indicating that the PCA may not have been branched from the medial femoral circumflex artery. In some cases of a defect of QF, it is possible that the feeding origin of the PCA is different from that in the normal hip. Thus, pre-operative evaluation of PCA based on MR angiography and/or CT angiography would be recommended. 5. Conclusions QF defects were observed in approximately 3% of our ON patients. Special considerations are necessary when planning RO on these patients followed by carefully performed surgery. Disclosure of interest T. Yamamoto perceives grants from AMED in relation with this work, Y. Nakashima declares that he has no competing interest but perceives fees from Kyocera and Zimmer outside the current study. G. Motomura, K. Karasuyama, T. Doi and Y. Iwamoto declare that they have no competing interest. Acknowledgments This work was supported in part by a research grant for intractable diseases from the AMED and a Grant-in-Aid in Scientific Research (No. 15K10479) from the Japan Society for the Promotion of Science.
References [1] Mankin HJ. Non-traumatic necrosis of bone (osteonecrosis). N Engl J Med 1992;326:1473–9. [2] Mont MA, Hungerford DS. Non-traumatic avascular necrosis of the femoral head. J Bone Joint Surg Am 1995;77:459–74. [3] Sugioka Y. Transtrochanteric anterior rotational osteotomy of the femoral head in the treatment of osteonecrosis affecting the hip; a new osteotomy operation. Clin Orthop Relat Res 1978;130:191–201. [4] Miyanishi K, Noguchi Y, Yamamoto T, Irisa T, Suenaga E, Jingushi S, Sugioka Y, Iwamoto Y. Prediction of the outcome of transtrochanteric rotational osteotomy for osteonecrosis based on the postoperative intact ratio. J Bone Joint Surg Br 2000;82:512–6. [5] Sugioka Y, Yamamoto T. Transtrochanteric posterior rotational osteotomy for osteonecrosis. Clin Orthop Relat Res 2008;466:1104–9. [6] Rosset P, Castaing J. Posterior circumflex artery: anatomical study. Technical interences for circular capsulotomy in Sugioka’s femoral osteotomy. Rev Chir Orthop 1988;74:203–8. [7] Courpied JP. Transtrochanteric rotation osteotomy for femoral head necrosis. Long-term results. Rev Chir Orthop 1994;80:694–701. [8] Dean MT, Cabanela ME. Transtrochanteric anterior rotational osteotomy for avascular necrosis of the femoral head: long-term results. J Bone Joint Surg Br 1993;75:597–601. [9] Gautier E, Ganz K, Krugel N, Gill T, Ganz R. Anatomy of the medial femoral circumflex artery and its surgical implications. J Bone Joint Surg Br 2000;82:679–83. [10] Atsumi T, Yamano K, Muraki M, Yoshihara S, Kajihara T. The blood supply of the lateral epiphyseal arteries in Perthes’ disease. J Bone Joint Surg Br 2000;82:392–8. [11] Bellot F, Havet E, Gabrion A, Meunier W, Mertl P, de Lestang M. Core decompression of the femoral head for avascular necrosis. Rev Chir Orthop 2005;91:114–23. [12] Mukisi-Mukaza M, Manicom O, Alexis C, Bashoun K, Donkerwolcke M, Burny F. Treatment of sickle cell disease’s hip necrosis by core decompression: a prospective case-control study. Orthop Traumatol Surg Res 2009;95: 498–504. [13] Sugano N, Atsumi T, Ohzono K, Kubo T, Hotokebuchi T, Takaoka K. The 2001 revised criteria for diagnosis, classification, and staging of idiopathic osteonecrosis of the femoral head. J Orthop Sci 2002;7:601–5. [14] Gray H. Anatomy of the human body. 29th edition Philadelphia: Lea & Febiger; 1973. p. 501. [15] Stibbe EP. Complete absence of the quadratus femoris. J Anat 1929;64(Pt 1):97. [16] Atsumi T. Hemodynamic study of the idiopathic necrosis of the femoral head using super-selective angiography. Nihon Seikeigea Gakkai Zasshi 1983;57:353–72.
Available online at
ScienceDirect www.sciencedirect.com
Original article
Results of the Sugioka transtrochanteric rotational osteotomy for osteonecrosis: Frequency and role of a defect of the quadratus femoris muscle in osteonecrosis progression T. Yamamoto ∗ , G. Motomura , K. Karasuyama , Y. Nakashima , T. Doi , Y. Iwamoto Department of Orthopaedic Surgery, Graduate School of Medical Sciences, Kyushu University, 3-1-1 Maidashi, Higashi-ku, 812-8582 Fukuoka, Japan
a r t i c l e
i n f o
Article history: Received 17 July 2015 Accepted 19 January 2016 Keywords: Osteonecrosis Femoral head Quadratus femoris Rotational osteotomy
a b s t r a c t Background: During transtrochanteric rotational osteotomy (RO), it is important to preserve the posterior column artery (PCA), which is generally located in the adipose tissue underneath the quadratus femoris muscle (QF). If there is a defect in the QF, the risk of injuring the PCA, subsequently resulting in total necrosis of the femoral head, may increase. Therefore, we investigated: (1) the frequency of defects of the QF at the time of RO, and (2) clinical outcome of RO based upon a defect of the QF. Hypothesis: The presence of defects of the QF at the time of RO could be detected pre-operatively by magnetic resonance imaging. Methods: RO was performed in 124 hips between 2001 and 2010. In all, 95 of the hips were in male patients and 29 in female patients. The mean age was 45.4 years (range: 11–61 years) at the time of surgery and MRI was performed before RO in all cases. We retrospectively evaluated the progression of a collapse through 3 years after RO. Results: MRI showed a defect in the QF in four hips (3.2%) (2 males, 2 females), all of which were confirmed intra-operatively. Among the four patients, one (25%) underwent total hip arthroplasty because of varus deformity of the osteotomy site due to total necrosis of the femoral head 1 year after RO. The 120 hips with a normal QF showed no evidence of total necrosis or progression of necrosis of the femoral head, indicating that the presence of defects of the QF may increase the risk of poor survivorship of this procedure. Conclusions: Defects of the QF have been reported to occur in 1–2% of all patients, whereas in our study the incidence in ON was approximately 3%. In ON patients with QF defects, pre-operative MRI evaluation of the QF appears to be important when planning RO, followed by a carefully performed surgical procedure. Level of evidence: IV; retrospective case series without control group. © 2016 Elsevier Masson SAS. All rights reserved.
1. Introduction Once subchondral collapse occurs in a patient with osteonecrosis (ON) of the femoral head, surgical treatment is necessary to relieve the pain and to obtain good hip function [1,2]. First developed by Sugioka in 1978 [3], transtrochanteric rotational osteotomy (RO) is a joint-preserving procedure used to treat ON. The procedure involves transposing an intact area to a weightbearing portion of the joint, resulting in transfer of the necrotic area to a non-weight-bearing area. The survival rate has been reported to be around 80%, while less than 20% of survival rate has also been reported, indicating that this procedure is technically demanding [4–8]. One of the most important aspects in performing RO
∗ Corresponding author. Tel.: +81 92 642 5487; fax: +81 92 642 5507. E-mail address: [email protected] (T. Yamamoto). http://dx.doi.org/10.1016/j.otsr.2016.01.017 1877-0568/© 2016 Elsevier Masson SAS. All rights reserved.
is to preserve the posterior column artery (PCA), a branch of the medial femoral circumflex artery, which supplies nutrients to the femoral head [9,10]. The PCA is generally located in the adipose tissue underneath the quadratus femoris muscle (QF), which is a flat, quadrilateral muscle between the gemellus inferior and the proximal margin of the adductor magnus. In order to expose the obturator externus, minimum release of QF is recommended, but if the QF is absent, the adipose tissue is directly exposed, which may increase the risk of injuring the PCA during the procedure, eventually resulting in total necrosis of the femoral head. The QF is thus an important anatomical signpost for performing RO safely. However the anatomical variations of the QF muscle are not accurately known. In addition, there is no information whether the presence of defects of the QF at the time of RO influences the survivorship of this procedure. Therefore we investigated the frequency of QF defects at the time of RO in ON patients and also assessed their influence on clinical outcomes of RO. The goals of
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Table 1 Clinical findings of the 4 patients with a defect of the quadratus femoris muscle. Patient number
Gender
Age
Etiology
Defect side
Necrosis side
Pre-operative stage and type
Procedure
Total necrosis of the femoral head (months)
1 2 3 4
Female Male Female Male
47 49 36 29
Corticosteroids Alcohol Corticosteroids Alcohol
Bilateral Left Bilateral Left
Bilateral Left Bilateral Bilateral
Stage Stage Stage Stage
Lt. PRO Lt. ARO Lt. PRO Lt. ARO
– – – + (10 months)
3A, type 3B, type 3A, type 3B, type
C2 C2 C2 C2
ARO: anterior rotational osteotomy; PRO: posterior rotational osteotomy; Rt.: right; Lt.: left.
the current study were to evaluate: (1) the frequency of defects of the QF at the time of RO, and (2) clinical outcome and survival of RO according to the presence of defects of the QF. Our hypothesis was that the presence of defects of the QF at the time of RO could be detected pre-operatively by magnetic resonance imaging.
2. Patients and methods
for 5 weeks, after which gradual weight-bearing was permitted. Full weight-bearing was permitted after 6 months. 2.3. Methods of assessment We evaluated radiographic evidence of total necrosis of the femoral head 3 years after the procedure based on AP and frog lateral views of all 124 hips. QF defects were pre-operatively assessed on MRI and checked during surgery.
2.1. Patients The institutional review board at our university approved this study. Between 2001 and 2010, transtrochanteric RO was performed in 124 hips (95 in males, 29 in females) of 109 patients whose average age was 45.4 years (range: 11–61 years) at the time of surgery. (During the same period, prosthetic hip replacement was performed in 200 ON hips, transtrochanteric varus osteotomy in 34 ON hips, but core decompression was done in none of the ON cases in our hospital [11,12]). RO was indicated and performed in patients who: (1) had a necrotic area in the anterior or posterior portion of the femoral head; (2) had an intact healthy area in the anterior or posterior portion; and, most importantly, (3) were predicted to have a postoperative intact area ratio over 34% after the RO [3,4]. Cases who fulfilled these criteria have been reported to have a low risk of progression of a collapse [4]. Based on the Japanese Investigation Committee Classification System of ON, 77 hips were stage 3A, 43 stage 3B, and 4 stage 4 (3A: collapse less than 2 mm, 3B: collapse over 3 mm), and one hip was categorized as type B, 18 as type C1, and 105 as type C2 [13]. (According to the Ficat and Arlet classification, 121 hips were in stage III and 4 in stage IV, while 121 hips in ARCO stage 3, and 4 in ARCO stage 4.) The etiology of ON was idiopathic in 5 hips, alcohol abuse in 50, post-trauma in 9 (including 11-year-old girl with ON after slipped capital femoral epiphysis), and corticosteroid use in 60. The presence of a QF defect was mainly investigated in all 124 hips based on intra-operative findings. In addition, preoperative MRI was examined whether only high-signal adipose tissue is observed without any evidence of muscle structure.
2.4. Statistical methods The prevalence of total necrosis of the femoral head in patients with a QF defect and those with a normal QF were statistically assessed using Fisher’s exact test. Statistical differences were considered significant when P < 0.05. 3. Results The pre-operative MRI examinations revealed a QF defect in 4 of the 124 hips with ON (3.2%) (2 males, 2 females) (Table 1). The etiology of the ON was alcohol abuse-related in two patients and corticosteroid-related in the other two. All the four cases were categorized as type C2 according the Japanese Investigation Committee Classification System of ON. The QF defects were confirmed intraoperatively in all four patients and no false negative cases were found. Anterior RO was performed in two patients and posterior RO in two. One of the four (25%) patients with a QF defect showed varus deformity of the osteotomy site resulting from total necrosis of the femoral head 10 months after the RO, resulting in conversion to a hip prosthesis (Fig. 1). The other three patients showed no evidence of total necrosis of the femoral head 3 years after RO. On the other hand, among the 120 RO cases in which the QF was normal, no hips showed progression of a collapse caused by total necrosis of the originally intact area 3 years after RO. This incidence was lower than that for the patients with a QF defect (P = 0.0323). 4. Discussion
2.2. Methods The basic RO surgical procedure has remained unchanged since it was described by Sugioka [3]. Briefly, it includes three osteotomies: (1) osteotomy of the greater trochanter; (2) intertrochanteric osteotomy, which passes from superolateral to inferomedial on the anteroposterior (AP) view; and (3) an osteotomy that passes from the proximal flare of the lesser trochanter inferolaterally toward the inferomedial extent of the primary osteotomy. During these osteotomies, preservation of the PCA (located in adipose tissue underneath the QF) is the most important procedure, so minimum release of QF in order to expose the obturator externus is recommended. To obtain rigid fixation, the K-MAX Adjustable Angle Hip Screw (K-MAX AA Hip Screw; Japan Medical Materials, Osaka, Japan) as well as two screws are used. Postoperatively, the patients were not allowed to bear weight
A QF defect has been observed in 1–2% of general patients in anatomical studies [14,15]. In the present study, the rate was approximately 3% in patients with ON who underwent RO at our institution. In addition, one of four patients with a QF defect underwent total necrosis of the femoral head, whereas cases with normal QF anatomy showed no evidence of total necrosis. This relatively high rate of total necrosis may indicate that when the QF is not observed another type of operation (e.g., transtrochanteric varus osteotomy) should be considered, although the number with a defect of QF muscle was only 4 hips and a defect of QF itself may not have been the direct cause of total necrosis. If the RO is the only joint-preserving procedure that is deemed appropriate, it is necessary to verify the location of the PCA pre-operatively using MR angiography or CT angiography to confirm the location of the PCA. If the PCA is not observed in its normal location, RO is not indicated.
T. Yamamoto et al. / Orthopaedics & Traumatology: Surgery & Research 102 (2016) 387–390
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Fig. 1. A 29-year-old man with alcohol-related osteonecrosis; a: on A-P view, subchondral collapse more than 3 mm is seen on the left hip; b: on a frog lateral view, the posterior part of the femoral head is intact and anterior RO was indicated; c: the T1-weighted MRI axial view shows that the quadratus femoris muscle (QF) (circled) on the right side is normal (arrows). However, on the left side (circled), only high-signal adipose tissue is observed (arrowheads); d: intra-operatively, the QF was not observed, and only adipose tissue was seen (arrowheads). The other obturator muscles, including the piriformis, obturator internus, gemellus, and obturator externus, were normal. GT: greater trochanter; LT: lesser trochanter; GM: gluteus medius; PR: piriformis; GS: gemellus superior; GI: gemellus inferior; VL: vastus lateralis; e: RO was performed with care so as not to damage the PCA or the adipose tissue. Postoperative intact area ratio was obtained around 50%; f: however, bone scintigraphy performed 5 weeks after RO showed a cold spot throughout the femoral head, indicating that there was no blood supply to it. Ten months after RO, varus deformity of the osteotomy site followed by a penetration of screw due to total necrosis of the femoral head was observed (black bar in e and f), when the Harris Hip Score was 43 points. Progression of a collapse is also observed (arrow) at the lateral portion of the femoral head; g: on a frog lateral view, anterior part of the femoral head showed a collapse (arrow). The histological examination of the resected femoral head revealed total necrosis of the femoral head.
There are several limitations in this study. First, it is unknown whether a defect of QF muscle itself was a direct cause of total necrosis of the femoral head in this study. It may be possible that other unknown factors may have influenced on postoperative total necrosis. Secondly, we focused only on ON patients for whom RO was indicated. Further study that includes other type of osteotomy, prosthetic replacements and non-operative cases is necessary to evaluate the precise prevalence of a QF defect in osteonecrosis cases. Thirdly, the number of cases with a defect of QF muscle was only 4 cases. In this study, statistical analysis was made based on this small number of cases and more documented cases are necessary. Finally, the relation between a QF defect and variants of the
PCA could not be analyzed in this study. Imaging studies using MR angiography or CT angiography are necessary. The obturator externus, which is located closely adjacent to the adipose tissue containing the PCA, must be completely dissected during RO in order to obtain sufficient rotation [3]. Also, the release of QF is necessary to expose this obturator externus, which should be minimum not to injure the PCA. In patients with a QF defect, the adipose tissue containing PCA is directly exposed. These conditions may increase the risk of injury of the PCA during surgery. Several variants of the PCA have been reported in ON cases, including the observation that the PCA is fed by a branch of the internal iliac artery, not from the medial femoral circumflex artery [10,16].
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Because all of the soft tissue containing a branch of the internal iliac artery needs be circumferentially resected around the femoral neck during an RO, such an abnormality may cause total necrosis of the femoral head because of disruption of the blood supply, which may subsequently result in varus deformity of the osteotomy site due to total necrosis of the femoral head. One of the four patients in this study underwent total necrosis of the femoral head despite a carefully performed procedure to prevent damage to the PCA and the medial femoral circumflex artery, indicating that the PCA may not have been branched from the medial femoral circumflex artery. In some cases of a defect of QF, it is possible that the feeding origin of the PCA is different from that in the normal hip. Thus, pre-operative evaluation of PCA based on MR angiography and/or CT angiography would be recommended. 5. Conclusions QF defects were observed in approximately 3% of our ON patients. Special considerations are necessary when planning RO on these patients followed by carefully performed surgery. Disclosure of interest T. Yamamoto perceives grants from AMED in relation with this work, Y. Nakashima declares that he has no competing interest but perceives fees from Kyocera and Zimmer outside the current study. G. Motomura, K. Karasuyama, T. Doi and Y. Iwamoto declare that they have no competing interest. Acknowledgments This work was supported in part by a research grant for intractable diseases from the AMED and a Grant-in-Aid in Scientific Research (No. 15K10479) from the Japan Society for the Promotion of Science.
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