Treatment of Congenital Hip Dislocation with Total Hip Prosthesis:
Congenital hip dislocation or displacement including a wide range of issues from insufficient acetabulum cover over the head of the femur, to full dislocation, is one of the most impactful factors of the secondary osteoarthritis emergence. In these cases, technical difficulties and complications, which are manifested through severe pain and limitation of daily activities, are more common in the total hip prosthesis (THP) practices in comparison to standard practices. While significant issues are not necessarily common in the cases of congenital hip displacement with a few anatomic defects in terms of the total hip prosthesis practices, in the cases of advanced displacement or dislocation the issues concerning acetabular or femoral reconstruction increase, which makes solutions more difficult. In parallel with the increase of standard total hip prosthesis practices in our country, the total hip prosthesis practices performed on the cases of hip displacement or dislocation have also increased. Therefore, this study focuses on conducting a literature analysis on the classification, pre-operation evaluation, approaches to overcome technical difficulties, and results of the total hip prosthesis practices concerning these cases.
Anatomy In the cases of congenital hip displacement or dislocation, the anatomic defects impacting the soft tissues and bone structure may vary depending on the severity of the displacement/dislocation, as well as the previous operations. Clinically or radiologically identifying and being aware of these variances during the operation will have a positive impact on the outcome. In subluxed cases the acetabulum is shallow, wide and elliptic. While the
anteromedial wall is thin and insufficient, the posterior area boasts a quite-well bone stock. In cases with upper dislocations, the same area and the pelvis part are smaller than the other. Each wall of the small and atrophic acetabulum is thin and soft; additionally, in most cases, its anteversion has increased. As anatomic defects in the femur; the neck is short, the head is small, the neck form degree is increased, the anteversion is apparent and the medullar channel in the isthmus area is thin, plane and tight due to the posterior placement of the great trochanter. In their study, Sugano, et al. have reported that the anterior-posterior diameter at the proximal area of the displaced femur is greater than that of the mediolateral. As a result of the anatomic defects in the bone structure, secondary variances occur in the soft tissues, as well. Depending on the degree of shift occurred at the femur towards the proximal, the muscle groups of hamstrings, adductors, and quadriceps shortens, and the iliopsoas tendon changes direction. The joint capsule that starts at the edge of acetabulum and ends around distal area of the femur neck appears similar to an hourglass due to the pressure by the iliopsoas muscle. There may be a location change at the sciatic nerves and femoris, which may suffer direct trauma during the operation (especially in extending the extremity).
Classification
Many classifications have been made in order to identify the differences in the degree of anatomic disorders in cases of congenital hip displacement or dislocation, to make choosing the surgical method easier in the total hip prosthesis practices, to set a standard in evaluating the clinical and radiological results and discussing the results reported in the literature. The most cited classification in the literature were made by Crowe, et al., Hartofilakidis, et al., and Eftekhar et al. In their research, where they radiologically classified the hips into 4 groups based on the shift of the femur head towards the proximal, and identified that the femur head height is normally equivalent of the 20% of the pelvis height, Crowe, et al. measured the horizontal
line connecting the teardrops, which normally should pass through the same level, and the differences in height identified at the meeting point of the femur head and neck. Thereafter, they classified their findings into 4 groups based on the ratio between the distance and the height of pelvis or femur head. In the Group I, the shift of femur head towards the proximal is lower than the 10% of the pelvis height, and the degree of subluxation is lower than 50% of the femur head height. In the Group II, the shift of femur head towards the proximal equals to 10-15% of the pelvis height, and the degree of subluxation equals to 50-75% of the femur head height. In the Group III, the shift of femur head towards the proximal equals to 15-20% of the pelvis height, and the degree of subluxation equals to 75-100% of the femur head height. In the Group IV, the shift of femur head towards the proximal is higher than the 20% of the pelvis height, and the degree of subluxation is higher than 100% of the femur head height.
Hartofilakidis, et al. classified the cases of hip displacement and dislocation into three groups; displacement, subtotal dislocation and total dislocation. In the cases classified under the displacement group, the acetabulum is insufficient and has become shallow due to the osteophyte developed inside thereof. In the cases classified under the subtotal dislocation group, the acetabulum has settled in the pseudo acetabulum which relates to the real one. In addition to showing an antero-posterior segmental insufficiency, the acetabulum is tight and shallow. In most of these cases the acetabular anteversion has been increased. In the cases classified under the total dislocation group, the head of the femur has moved towards the supero-posterior of the acetabulum and settled under the iliac wing. All sides of the real acetabulum are insufficient, and show tightness, extended antevert and insufficient depth. In the classification, Eftekhar has divided the cases of congenital hip displacement and dislocation into 4 groups. In the cases classified under Group A, the acetabulum is displaced and its supero-inferior part has slightly extended. Also, there may be certain deformations in the
head of the femur. In the cases classified under Group B, the real acetabulum is either rudimentary or underdeveloped, and the height of the acetabulum is medium. In the cases classified under Group C, the variance from those classified under Group B is the emergence of a pseudo acetabulum in the upper section. In the cases classified under Group D, the head of the femur has completely spread outside the acetabulum and has no relation to the ileum. Among these popular classifications of congenital hip displacement or dislocation cases, the classification made by Crowe, et al. is the most quantitative and practical approach.
Patient Evaluation and Pre-Operation Planning
In the cases of congenital hip displacement or dislocation, the total hip prosthesis practices typically depend on the severity of the case, as well as the secondary osteoarthritic changes, the availability of the bone stock, the patient’s age and functional expectations. Although most cases show the symptoms of limping, height difference in the lower extremity, waist and knee pain, the primary symptom of this condition is hip pain. In some cases, however, the first symptom may manifest itself through hip pain caused by an excessive compensatory lumbar lordosis. As the pain is the most significant indication in the practice of total hip prosthesis, it should be attempted to treat the condition with conservative methods before proceeding with the surgery. Despite showing the symptom of excessive limping, most patients with bilateral hip dislocation may continue their daily lives in a functional manner while suffering mild pain. However, in the cases classified under Type II and Type III according to Crowe’s classification, the degenerative variances and symptoms usually emerge in the earlier stages in comparison those classified under Type I and Type IV, making the total hip prosthesis practices a necessity. Before the operation, the patients should be informed on the neurologic, vascular or potential complication-related aspects of the prosthesis application, as well as the impossibility of a full recovery, depending on the length of the extremity and the severity of the limping.
Identifying the pelvic tilt, lumbosacral flexibility, fixed deformities of the hip joint, and the real or visible difference in length during the pre-operation planning phase is crucial for deciding on the method of measurement and surgical application to remove the extremity in length difference. Having been briefed on the previous surgeries or practices also helps identifying the direction on the surgical approach and foreseein the degree of difficulty concerning the soft tissue dissection. The potential effects of these surgeries on results of the total hip prosthesis operations to be performed on the cases of hip displacement or dislocation. Periacetabular osteotomies strengthens the acetabular cover and helps to create the necessary bone stock for covering the component. The existence of the an implant pertaining to the previous surgery is crucial. Removing the implants embedded in the bone due to a growth in the femur proximal may increase the morbidity of the surgery. To remove the implant, certain tools such as a metal cutting device, a screwdriver with various heads, a screw remover, and a rounder with a high cycle capacity may be necessary. Some authors have reported that the rate of complication and revision is high in the total hip prosthesis practices following a femoral osteotomy. On the other hand, Boos, et al. reported no significant increase in the rate of complication compared to primary cases while acknowledging that the operation time is longer, and the surgical dissection is more difficult in such cases.
Pre-operative planning is very important for the procurement of appropriate equipment and prosthesis. Along with the anteroposterior pelvis and hip radiography, which are used as standard in the radiological evaluation of the acetabulum and femur, Judet radiography can be used to evaluate the adequacy of the acetabular bone stock. In addition, computerized tomography examination can be used to obtain information about the femoral anteversion and the degree of acetabular coverage. In their study, Kim et al. stated that they used radiography in the frog position to determine whether the dislocation can be reduced and thus to obtain information about the problems that may occur during surgery, and MRI to evaluate
the anatomical abnormalities in soft tissues in patients with high dislocation. Considering that changes may be made in the selection or application of the prosthesis to be used in cases of hip dysplasia or dislocation, the importance of the preparation of the prosthesis set before surgery becomes clear.
In the reconstruction of the acetabulum; it is important to consider significant factors such as placing the component in the real acetabulum by using the small acetabular component, and using the femoral head as a graft to support the acetabular component, and to make preparations accordingly for a successful operation. In the reconstruction of the femur; the femoral component with a small straight stem, a 22 mm head, a polyethylene component with an inner diameter of 22 mm, and osteotomy equipment should be made available, since it may be necessary to perform an osteotomy to eliminate the extremity differences depending on the stenosis of the medullary canal and the patient’s previous surgeries.
Surgery Techniques
Surgical Approaches While the anterolateral or posterolateral approaches are used in the cases of hip displacement or subtotal dislocation, the transtrochanteric or subtrochanteric approaches can be used in cases of high dislocation and shortening osteotomy or in cases where abductor mechanism needs to be repaired. The transtrochanteric approach provides easy access to the femoral body to perform osteotomy or to remove the implants used in previous operations, and allows revealing of the acetabulum, and using the femoral head as a graft. In addition, by allowing the trochanteric part to be displaced proximally or distally, this approach helps to eliminate the limb length difference and to create the abductor mechanism. In the subtrochanteric approach, similar to the transtrochanteric approach, the proximal part can be shifted superiorly or anteriorly after the osteotomy to expose the acetabulum. In cases where the anatomical hip
center is achieved, the subtrochanteric approach should be preferred to prevent trochanteric nonunion and excessive displacement problems that may otherwise occur with the transtrochanteric approach.
Reconstruction of the Acetabulum
In cases of congenital hip displacement or dislocation, the most important part of the surgery is reconstructing the acetabular. Although the high placement of the acetabular component without lateral insertion is accepted, it is recommended to place it in the real acetabulum as much as possible. In his studies, Delp reported that the abductor power deficiency caused by the upper placement of the acetabulum is compensated and eliminated by lengthening of the femoral component, but it cannot be compensated in the superolateral location. In some cases, the acetabular component is placed in the real acetabulum, while the use of the bone stock between the pubis and the ischion arms is important for component stability in preserving the sclerotized subchondral bone in the superior part of the real acetabulum (inferior part of the pseudo acetabulum) to support the superior part of the acetabular component.
In a case study, Paavilainen reported that 21 (31.3%) of the acetabular components were placed in the real acetabulum, and 46 (68.7%) were placed slightly below the real acetabulum. Achieving an acceptable bone coverage of the acetabular component is the most important stage of reconstruction. Acceptable bone coverage in the placement of the acetabular component to the real acetabulum is very important to ensure sufficient stability, and in many applications with or without cement (porous surface and screw fixing); medialization of the prosthesis can be achieved by using a small acetabular component, a deep reamer or a controlled fracture of the medial cortex. Moreover, especially in the Crowe Type III and certain Type II and IV cases, the femoral head is used as an autograft in the insufficient supero-posterior part of the acetabulum or the
acetabular component may need to be placed slightly above the real acetabulum. For placing of the acetabular component in the real acetabulum as much as possible in cases with congenital hip dislocation or displacement, it is recommended to stabilize the pelvis by obtaining sufficient abduction force, to eliminate the limb length difference, and to achieve an acceptable prosthesis stability, especially in cementless applications. While the results of the cemented acetabular component applications are similar to the cementless applications among the elderly, the results of cementless application of acetabular component are better in younger patients.
High Placement of the Acetabular Component (High Hip Center)
In cases of congenital hip displacement or dislocation, where the acetabular component cannot be placed in the real acetabulum, changes in the hip rotation center will significantly alter the hip biomechanics and negatively affect the durability of the reconstruction. In the study that they conducted by developing a mathematical model, Johnston, et al. stated that the force on the hip joint decreased significantly when the hip center was displaced anteriorly, inferiorly, and especially medially, while a significant increase occurred in the lateral, posterior and superior displacements.
In the study conducted with the three-dimensional computerized model they developed Delp et al. showed that, while the negative effect of the superolateral displacement of the hip center on abductor power is compensated by the lengthening of the femoral neck, it cannot be compensated for the supero-lateral displacement. Some authors reported good results for superior placement of the acetabular component without lateral placement, in cases where anatomical placement of the acetabular component could not be achieved in clinical studies.
Russotti and Harris reported acetabular loosening in 6 (16%) cases in their study involving 37 cases, in which they reported that the component loosening was not related to high hip center in cases with only superior displacement.
Covering the Acetabular Component with Bone
It is suggested that it is appropriate to cover 70-80% of the acetabular component with an intact acetabular bone and the remaining 20-30% with a morselized autograft or an allograft. Some authors reported that if 75-80% of the acetabular component is covered by the acetabular bone it is not necessary to use grafts for support, provided that the anterior and posterior bone stock can provide sufficient stability.
In Linde’s study, the determinants of loosening of the acetabular component were reported as the absence of lateral bone support that develops depending on the degree of dislocation and the higher placement of the acetabular component compared to the real acetabulum. When superolateral coverage is insufficient; The force coming to the acetabulum concentrates in the posterosuperior part and has a negative effect between the bone cement or the bone acetabular component. In cases where more than 20-30% of the acetabular component is not covered with acetabular bone, the femoral head can be used as a graft to support the acetabular component.
The amount of covering the acetabular component of the graft is very important, and this ratio should not be more than 50% or even exceed 40%. As the rate of covering the acetabular component with graft increases, the loosening rate of the prosthesis also increases.
In Mulory and Harris’s series, the loosening rate was indicated at 67% in cases where the cemented acetabular component was covered with a graft of 40% or more (40-70%), while this rate was indicated at 21% in cases where the graft coverage was 40% or less (20-40%).
In their study where they applied cement acetabular component with 20 cases, Iona and Matsuno stated that the average graft coverage was 26% (11-39%) and the graft coverage was 28% in three cases with loosening, and they stated that there was no significant relationship between loosening and graft coverage. Morsi et al. stated that 13 of the acetebular component were cemented (average follow-up of 9.7 years) and 17 were uncemented (average follow-up of 6.6 years) in the radiological examination of total hip prosthesis cases, and the average graft coverage was 28% (20-40%) in the cemented group. 15.4%) and in 1 (5.8%) case in the cementless group, revision was applied due to loosening.
Hasegawa et al. reported in their study, with an average of 58 months of follow-up, that the coverage of the cementless acetabular component with the graft was on average 27% (14-44%) and that there was no problem with loosening.
Using Small Acetabular Component
It is recommended to use cemented or uncemented small acetabular component in order to obtain sufficient bone coverage of the acetabular component while preserving the acetabular bone stock. When the acetabular bone stock is insufficient, making sure that the apex of the acetabulum is superior to the lateral edge reduces the risk of lateral insertion of the acetabular component and ensures the protection of the lateral wall by facilitating the insertion of the component medially. Excess reamer for medialization reduces the bone stock, causing axial migration of the component, loss of position and fractures in the acetabulum. When using cemented or uncemented acetabular component, it will be appropriate to use the femoral head as 22 or 26 mm in order to have sufficient polyethylene thickness. Sochart and Porter, in their 20-year follow-up study involving 60 cases, reported that they used acetabular components with 38 mm or less cement in 43 (72%) cases and performed revision in 22 (37%) cases. Reporting the long-term (244 months) results of total hip prosthesis in their study, Sochrat and Porter stated that small (38 mm) cemented acetabular component were used on 43 (72%) out of 60 cases – 44 of which were cases of congenital hip displacement and dislocated hips. Bobak et al. stated that 31 of the cement acetabular prostheses they placed were 40 mm, 5 were 43 mm, and 9 were 38 mm. In their study of 25 cases where they applied cementless total hip prosthesis, Hasegawa et al. reported the acetabular component size between 44 mm and 52 mm, while stating that the preferred size was 46 mm. Cameron et al. reported that the largest acetabular component they used in their study involving 71 cases was 48 mm.
Creation of Controlled Fracture in the Acetabular Medial (Cotiloplasty)
To solve the problem of insufficient bone stock in placing the acetabular component in its real place, it is recommended to increase the bone coverage and stability by medializing the component by creating a controlled fracture in the medial wall of the acetabulum. Before the cemented or uncemented acetabular component is placed, the medial wall of the acetabulum with a controlled fracture should be supported with a graft. In this method that allows the acetabular component to be placed medially; the center of the acetabulum may be displaced slightly downward, while providing anterior and posterior coverage of the component.
Hartofilakidis et al. reported that they got excellent and good results in 81 (94%) of 86 cases who had a follow-up of at least 2 and at most 15 years, and they performed acetabular revision in only 2 cases. They stated the survival rate as 100% at 5-year follow-up and 93% at 10-year follow-up. Using the cotyloplasty technique to obtain good results in their respective cases, Symenoides et al. reported that they did use cement, while Paavilainen et al. reported that they preferred cementless applications.
Femoral Reconstruction
In the cases of congenital hip displacement or dislocation, femoral reconstruction is very difficult due to femoral hypoplasia, narrow medullary canal, developmental and rotational disorders, and previous subtrochanteric or intertrochanteric osteotomies. In addition, in cases where shortening osteotomy is required in order to achieve hip reduction and to eliminate the extremity length difference, determining the osteotomy location, as well as the shape and amount of the shortening creates technical difficulties in comparison to standard primary total hip prosthesis applications. In cases with previous femoral osteotomy history, corrective osteotomies may be required to place the femoral stem in the appropriate position. During the preparation of the narrow femoral canal or the placement of a cementless prosthesis, great care should be taken, considering the possibility of fracture or perforation in the proximal femur. In some cases, when the femoral component cannot be placed due to femoral canal stenosis, the necessary position can be achieved by creating a fissure line in the antero-posterior direction in the 8-10 cm section of the proximal femur. The fissure line should be supported with a graft and fixed with screws for its stability. Due to the anatomical structure of the femur, in many cases, after metaphyseal osteotomy, a small, short, straight, cemented or uncemented femoral component can be placed directly into the femoral shaft for reconstruction.
Crowe et al. reported that small femoral components produced in normal sizes in Crowe Type I, Type II, and Type III cases. And in Crowe Type IV cases, reconstruction can be performed by making a neck cut that includes the calcar region of the femur and using the narrow and flat femoral components with a reduced medial edge.
When the acetabular component is placed in the real acetabulum, in many cases, the femoral shortening osteotomy is required to achieve hip reduction and to eliminate the extremity difference in length. Osteotomies enable correcting the rotation deformity and obtaining length in the lower extremity, despite shortening of the femur. When the rotation deformity (anteversion) is more than 40°, it is recommended to use osteotomy or specially made implants to correct the rotation deformity, even if shortening osteotomy is not required. Femoral shortening osteotomy can be performed around the trochanteric or subtrochanteric region. Subtrochanteric osteotomy can be in the form of step-cut, Chevron or oblique osteotomy. Since it allows the structure of the femur to be closer to its normal position, provides better fixation in the metaphyseal region, and enables removing of that part in some cases with very thin femoral medulla, the subtrochanteric osteotomy has been preferred in lieu of trochanteric osteotomy, in the recent years. Generally it is recommended that the limb extension should not be more than 4 cm as it may cause sciatic nerve damage. Hartofilakidis stated that in order to prevent possible damage to the sciatic nerve, it would be appropriate to keep the hip and knee joints in 25-30° flexion for a few days after the surgery. Cameron et al. reported that in their study of 71 cases, in which they applied cementless total hip prosthesis, only 2 cases (Crowe type IV) developed low-grade radiolucency in the femoral component in the non-porous surface area; femoral nerve involvement in 1 case; and sciatic nerve involvement in 2 cases. In order to decide the amount of shortening osteotomy after a subtrochanteric femoral osteotomy, the proximal femur with a trial prosthesis placed in the acetabular component, which has been reconstructed, is reduced and the distal part of the proximal region is determined by applying traction to the distal of the osteotomy. Then, an osteotomy is performed, and the femoral component is applied with or without using cement, depending on the preparation. After the osteotomy, the femoral parts can be fixed on the area of osteotomy with the help of a wire or cable, and they can be used as vascularized autografts.
Woolson and Harris reported loosening of the femoral component in 4 cases (7%) in their study of 55 cases, in which cemented total hip prosthesis was applied, with an average follow-up of 4.8 years. Sochart reported that they performed revision due to acetabular loosening in 1 case among 60 congenital hip dislocation cases underwent cemented total hip prosthesis with an average follow-up of 244 months, and had 3 cases of infection, in the follow-up of 74 uncemented total hip prosthesis cases for an average of 7.2 years. Moreover, they did not have had any complication related to the femoral component.
Hasegawa did not mention any problem related with the cementless component in the chapter of his study where he discussed the complications. Matsui et al. did not detect osteolysis around the acetabular component, in 47 of 51 cases, on whom they applied cementless (all surface covered with porosis) total hip prosthesis. In the 5-9 year follow-up, 63% reported excellent, 37% reported good results. On the other hand, osteolysis was detected around the femoral component in only 1 case.
Reconstruction of the hip abductor mechanism after osteotomy is very important for the success of the surgery and for the recovery of hip functions. For the mobilization of the trochanter after trochanteric osteotomy, achieving very good capsular release, m. Iliopsoas, and m. gluteus maximus, it is recommended that insertion is performed by changing and doing a fixation in the abduction. The patient is advised not to carry extra load and not to perform active abduction for three months. When subtrochanteric osteotomy is performed, it intervention to the abductor muscle group and trochanteric region is generally not necessary to provide reduction and relaxation. When, in some cases, hip reduction could not be achieved after femoral shortening osteotomy, the length of the abductor muscle tendons can be extended by releasing the z-plasty or the adhesion points towards the ileum wing. In such cases, it is necessary to fix the hip for 6 weeks to prevent stability problems in the postoperative hip. Anatomically, it is appropriate to fix the trochanter to the tensor fascia lata, when the reduction of the trochanter cannot be achieved after osteotomy, especially in cases with very small or fragmented trochanter. In this case, a very good and long-term rehabilitation is required.
Complications
The effect of the degree of displacement or dislocation on the results of total hip replacement is not clear. It is generally reported that as the degree of dislocation increases, the hip evaluation score decreases, and revision and surgery complications increase, simultaneously. In their prospective study involving 71 patients with hip displacement and 22 control groups, who were followed up for an average of 3.5 years, Cameron et al. investigated the effect of the classification made by Crowe et al. In that study, they showed that there was no significant difference between Crowe Type I and control group cases, in terms of clinical, functional results and complications. On the other hand, Crowe reported complications such as femoral nerve damage in 1, sciatic nerve damage in 2, femoral fracture in 1, and deformation in the osteotomy area in 1 of the Type IV cases; underlining that these were significantly higher than those of Crowe Type II and Type III cases. Sochart and Porter, however, reported that there was no significant difference between the cases when the results obtained in their study of 60 cases with 244 months of follow-up were analyzed according to the Crowe classification. Moreover, they stated that the survival rate of the acetabular component for 10 to 25 years was 97% and 58%, respectively, and that the survival rate of the femoral component was 97% and 54%.
In their study involving 182 patients who underwent total hip prosthesis with an average follow-up of 9.9 years, Numair et al. reported a revision rate of 17% in the acetabular component in 46 Crowe Type IV cases; and 10% revision rate in 136 Crowe Type I-II-III cases. Moreover, they stated that they performed revision on the femoral component only for 5 of the cases (3%), which were not correlated with the degree of dislocation.
According to Harris hip evaluation criteria, Cameron et al. reported excellent results in 75% of the Crowe Type II and Type III cases, and 59% in the Type IV cases. In their study involving 59 cases followed for minimum 10 and maximum 21 years, MacKenzie et al. stated that they found 2 Crowe Type II, and 3 Type III cases with acetabular loosening that did not require revision; and 4 Type IV cases, 2 of whom underwent revision surgery.
While the nerve damage is reported at 0.5-2% (75-80) in cases with primary THP, it reported at 3-15% in cases with congenital hip displacement or dislocation. There are different opinions on the ideal extension of the extremity to prevent the occurrence of nerve damage.
Although Garvin et al. stated that limiting limb lengthening to 2 cm would be appropriate to prevent nerve damage, Nercessian et al. reported that limb extension up to 10% of femur length could be safe in terms of preventing nerve damage. Cameron et al. found that limb lengthening was more than 4 cm in 3 femoral cases, and in 3 sciatic nerve involvement cases during their examination of 106 patients, who underwent total hip prosthesis.
In cases of congenital hip displacement or dislocation, the dislocation rate increases up to 511% after total hip prosthesis application. Trochanteric nonunion rate was found to be the highest, between 10 and 29%. Among the most common causes of dislocation after a total hip replacement are; trochanteric nonunion, impingement caused by high placement or excessive medialization of the acetabular component. In flexion and internal rotation of the hip, the femoral component touches the anterior part of the acetabulum, and in extension and external rotation, the ischia and the posterior part of the acetabulum cause dislocation. To prevent this situation, the offset of the femoral component may be increased or the rectus femoris muscle may be relaxed, the anterior inferior iliac process or the part of the ischia that touches the femoral component may need to be resected.
Fracture or perforation in the medullary canal may occur in the preparation of the proximal part of the femur. Perforation in the medullary canal with or without a graft, with the help of a broken wire or cable in the proximal femur, can be repaired using a long-stem femoral component that passes distal to the perforation area or a graft with the help of a wire or cable.
Trendelenburg symptom continues in patients whose hip abduction mechanism cannot be repaired sufficiently after the surgery. Fredin et al. reported in their study of 21 cases with an average follow-up of 7.5 years, postoperative Trendelenburg symptom was negative in 7 cases, positive in 7 cases, and could not be evaluated in 7 cases. Hartofilakidis et al. in their study of 73 cases with an average follow-up of 7.1 years (2-20 years), found that Trendelenburg symptom was positive in all preoperative cases, and negative in 41 (61%), mildly positive in 26 (39%) postoperative cases.
In cases of congenital hip displacement or dislocation, infection is higher than primary total hip prosthesis applications due to reasons such as long operation time, requiring more dissection, and using grafts.
Conclusion
In cases of congenital hip discplacement or dislocation, the results of total hip prosthesis applications in the surgical treatment of pain and loss of function that do not respond to conservative treatment methods developed as a result of secondary osteoarthritis are quite good. These young and expectant patients generally do not accept arthrodesis. In cases with moderate impairment (Crowe Type I, Type II), the application of total hip prosthesis does not require special experience, while surgical technique difficulties arise during the reconstruction in advanced cases (Crowe Type III, Type IV). In general, the higher the degree of dislocation (especially Crowe Type IV), the lower the postoperative hip assessment score and the increase in the revision rate are closely related to the degree of anatomic disorder. Morbidity and poor results of total hip prosthesis applications in Crowe Type III and Type IV cases are higher than the results of primary total hip replacement. Although there is controversy regarding the acceptance of the methods applied in acetabular reconstruction, there is a consensus on the placement of the cementless acetabular component, the first fixation of which was provided with a screw, into the real acetabulum. If the coverage of the acetabular component with the host bone is less than 70%, the femoral head is used as an autograft for support. The amount of covering the acetabular component of the graft is very important, and this ratio should not be more than 50% or even exceed 40%. If the part of the acetabular component not covered with the host bone is less than 30%, cement, morsalized autograft or allograft can be used to support this part. No consensus has yet been reached on the results of the placement of the acetabular component with the application of cotyloplast and acceptable high hip center, and the evaluation of the results obtained with these applications still continues.
Femoral reconstruction is not as controversial as acetabular reconstruction. With good preparation and planning before the operation, many difficulties can be solved by performing proximal (trochanteric) or sutrochanteric osteotomy and using modular or custom-made implants. Femoral component selection is generally related to the size and structure of the femur and the required number of osteotomies or length of shortness. In the recent years, subtrochanteric osteotomy has been preferred in lieu of trochanteric osteotomy, because it allows the structure of the femur to be closer to its normal position, and provides better fixation in the metaphyseal region, and enables removal of that part in some cases with very thin femoral medulla.