Title: Preoperative Planning for DDH Revision Surgery “Tips and Tricks”
Author(s): Mousa M. Alhaosawi MD 1, Amir Shahryar Ariamanesh MD 2*
Affiliattion(s): 1- King Fahad Hospital, Almadinah Almunawwarah, Saudi Arabia 2- Mashhad University of Medical Sciences, Mashhad, Iran
* Corresponding Author
Vol 1, Num 2, October 2014
Perioperative and postoperative complications and unexpected surgical findings are much more common in revision surgery for developmental dysplasia of the hip than they are in primary surgery. The article explains the preoperative planning process step by step detailing the expected problems and keeping an open eye for the unexpected ones.
Keywords:DDH, Hip dysplasia, Preoperative planning, Redislocation, Revision surgery
Primary surgery for developmental dysplasia of the hip (DDH) can be easy and straight forward and can be on the other hand difficult and complicated with redislocation. Perioperative and postoperative complications and unexpected surgical findings are much more common in revision surgery for DDH than they are in primary surgery. Preoperative planning entails numerous crucial steps before the surgeon decides which instruments, implants, bone grafts, and surgical approach will be required. There are often problems during revision surgery that require careful tissue dissection, implants, bone grafts, and/or other accessories that may not be available readily in the operative room unless the potential need for these items was anticipated.
Anticipation of possible complications also is crucial so that informed consent can be provided. Preoperatively, patients and their families should be counseled regarding the specific additional risks associated with revision surgery of DDH. Preoperative planning is the first and one of the most important steps in performing a revision DDH Surgery.
An organized approach reduces operative time, minimizes risks, decreases stress, and increases the success rate. It is important to consider the entire patient rather than just the hip so that the risk of major perioperative complications can be minimized. The preoperative planning includes obtaining a thorough history, a complete physical examination, appropriate preoperative imaging and establishing an accurate diagnosis.
Establishing an accurate diagnosis is the first step in successful planning for revision surgery of DDH, and this will be through:
A detailed history of all prior operations, and treatment interventions should be obtained. A history of conservative treatment and history of hip surgery (age, time of diagnosis, time and type of surgery, period of immobilization and postoperative protocol) should alert the surgeon to the reasons of failure of the primary surgery. Johari and Wadia divided reasons of failure of the primary surgery nicely into three categories: immediate, delayed and late failures.(1)
a) Immediate failures, which can be:
1- Approach related errors (inadequate exposure like in medial approach in walking children.(1,2)
2- Technical errors of open reduction (failure to release the obstructing soft tissue, like an inverted limbus or more importantly the inferior structures; the transverse acetabular ligament, ligamentum teres and/or inferior capsule, also inadequate capsulorrhaphy and/or failure to release the iliopsaos tendon may contribute to failure.(1,2,3,4)
3- Technical errors of procedures performed in addition to open reduction (Fig 1); failure to perform femoral shortening osteotomy when needed combined with an acetabuloplasty that increases the pressure on the femoral head, excessive derotation osteotomy of an anteverted femoral head combined with a Salter osteotomy, and posterior acetabular wall deficiency (2) and failure to perform derotation osteotomy of a severely anteverted femoral head (Fig 1).
b) Delayed failures
1- Inadequate capsulorrhaphy.
2- Inadequate immobilization.(1, 5)
3- Inadequate stabilization of the graft or the iliac bone osteotomy.
c) Late failures
1- Failed acetabular remodeling, which can be related to technical errors (injury to secondary growth center)(Fig 2).(1)
2- Abnormal femoral remodeling.
Review of hospital records from previous operations may provide important information, which often helps in preoperative planning. Patients who had the primary surgery in another facility need to bring detailed report of the previous interventions including operative reports and radiographic films. In the history the review of systems is important, as patients treated for revision DDH Surgery may have associated medical conditions that require evaluation and occasionally, treatment before surgery is performed.
The first useful step in the physical examination is to observe the child's gait. A positive Trendelenburg gait indicates poor abductor function, which may be due to weakness or paralysis, high riding trochanter or hip dislocation. Inspection of the wound is important to plan the operative incision relative to previous incisions. It is not advisable to make a second, parallel incision, to avoid post-operative skin necroses.
The active and passive ranges of motion should be determined especially to look for fixed deformities. Patients who have a partially or completely stiff hip may require comprehensive hip physiotherapy program, and institution of home program of skin traction for 2 to 6 weeks can be beneficial in some cases.(4,6) Soft tissues around the hip should also be assessed prior to surgery, especially obstructing muscles (adductor longus, and iliopsoas). This reveals which muscles need to be addressed properly during revision surgery. Ligament laxity is common in patients with DDH, but syndromic ligament laxity need to be looked at differently as it might be a factor in the redislocation. Teratologic dislocations are known to be difficult to treat conservatively and operatively with usually lower outcome.
Measurement of limb length is a standard part of the physical examination and it is also relevant to preoperative planning.
The radiographic measurements should be of good quality and should be correlated with findings on physical examination. If possible the radiographs at the time of diagnosis and before the primary surgery, the perioperative, the immediate post-operative, when redislocation was first diagnosed and the present radiographs need to be studied in a sequential order to identify the period when the problem started as management may differ accordingly.
The progression of the acetabular index and progression of the neck-shaft angle from the time of diagnosis to the present through the primary surgery is important to note. The shape and size of the femoral head, the length of the femoral neck, the articulo-trochantric distance and degree of osteopenia of the upper femur must be noted as well. It is essential to evaluate for evidence of avascular necrosis (AVN) and if it is noted, it should be categorized before final open reduction for follow-up documentation.
Radiographs with Judet views are useful for assessing acetabular bone stock especially if osteotomy of the acetabulum is planned during revision. A cross-table lateral radiograph of the acetabulum is useful for evaluating acetabular version, which is an important factor if instability is suspected. If an osteotomy or another surgical procedure has been performed on the femur, anteroposterior and lateral radiographs of the entire femur are needed.
Anteroposterior hip arthrogram (Fig 3) is another useful radiological assessment tool. It is a dynamic study, which can show intra and extra-articular obstacles. Lateral arthrogram can assess the site of acetabular deficiency to plan the acetabular osteotomy accordingly, which can be performed during the same anesthetics.
A computed tomography scan with transaxial section through the hip is an excellent method of showing displacement of femoral head from the acetabulum. The other useful parameters that can be measured on the axial cut are the degree of femoral and acetabular anteversion and femoral head size (Fig 4).(7)
Magnetic resonance imaging at the moment seems to be the most promising investigation to plan revision surgery for DDH.(1) Apart from being non-invasive and having no radiation risk, its ability to delineate soft tissues from cartilage and bone makes it a potentially useful tool in identifying the exact intra-articular pathology responsible for failure of previous surgery. Besides, it can also demonstrate the presence and the degree of AVN of the femoral head. In one study AVN had developed in more than half the hips, usually before the revision surgery.(8) The major drawback is the need for sedation or anesthetics in this age group.
Lab testing is frequently performed preoperatively, most commonly to assess for possible infection related to the previous surgery. The hemoglobin level, hematocrit, and mean cell volume can reveal anemia, and these findings should guide preoperative management or additional investigations.
Malnutrition is a risk factor for infection and should be corrected, if possible, prior to elective surgery. The preoperative nutritional status can be evaluated on the basis of serum protein levels and the total lymphocyte count.
Revision surgery is an elective surgery, so the patient should be properly evaluated and consultation of other specialties should be done when deemed necessary. The patient should be in the best shape possible for the surgery in order to reduce the postoperative complications. The surgeon might consult his colleagues, and the parents may get second opinion for reassurance.
Communication with the operating room team in advance of the procedure facilitates efficient surgery. Such an organized approach helps the patient and family to provide more specific informed consent and prepares the surgeon and the operative team for the surgery. These steps help to reduce the operative time, minimize the risk of complications, and improve the chances of success of a revision surgery for DDH.
The type of surgery would depend on whether the acetabulum is dysplastic or not and where is the acetabular deficiency. Also it would depend on the femoral head wither it is subluxated, or dislocated, whether it is anteverted or not and wither the femoral neck is in valgus deformity or not. Few cases may require open reduction only but the majority will need additional combination relocation procedures, which may have to be carried out either in a staged manner or in the same setting. Few studies recommend single stage surgery (1,9), however, this can be a demanding surgical exercise.
Surgeons dealing with revision surgery should expect that the tissue planes might be distorted and muscles may be seen as one fibrotic scar tissue that necessitates handling with extreme gentleness in order to avoid or at least minimize post-operative stiffness and iatrogenic neurovascular injuries. If another surgeon performed the primary surgery, one should expect the possibility of abnormal anatomy secondary to tough tissue handling and extreme caution should be practiced during dissection.
The anterior approach is the best for revision surgery.(8) Placement of the incision while making provisions for the previous scar is a very crucial step as if it is too high or too low it leads to undue stretching of tissues and poor visualization of the joint cavity especially the inferior and posterior acetabular margin and joint capsule. Careful dissection of the lateral cutaneous nerve of the thigh from scar tissue should be done in order to avoid post-operative painful parasthesia or numbness. Additional lateral approach will be needed for femoral osteotomy if that was necessary. If femoral osteotomy is indicated adequate amount of bone and appropriate wedges should be removed to achieve appropriate shorting, varus and/or rotation correction as deemed necessary. A subtrochanteric femoral osteotomy is a better choice of osteotomy for coxa valga due to its lower complication rate as compared to an intertrochanteric osteotomy.(10) It is advisable to use the bone obtained from the femoral osteotomy as a graft to open a wedge of the acetabular osteotomy to eliminate the risk of graft resorption.(11)
The choice of the acetabular osteotomy depends upon the cause of failure of the primary surgery, the status of the joint, the age of the patient and the competence of the surgeon in executing the different acetabular osteotomies to improve the coverage of the femoral head and thus treat severe preexisting acetabular dysplasia and stabilize the reduction.
The double osteotomy, triple osteotomy, and spherical periacetabular osteotomies requires technical expertise and are best referred to a trained expert in a well-equipped center. Injury to spermatic cord, bladder and urethra has been reported.
Salter's innominate osteotomy still remains a popular and widely used pelvic procedure. The use of threaded K-wire helps in preventing both graft and wire migration. Complications described using this procedure are avascular necrosis of the femoral head, resubluxation, secondary displacement of the osteotomy, premature closure of the triradiate cartilage and transient stiffness of the hip.
The Dega's osteotomy is a good alternative to the pemberton's osteotomy but proper case selection is very important. Both osteotomies reduce the capacity of the acetabulum.
Shelf procedures and the Chiari's osteotomy are generally indicated in older children and adolescents with acetabular dysplasia. Slotted acetabular augmentation has been used as an alternative to Chiari's osteotomy when lateralization of the hip is not very excessive. Unsatisfactory results of this procedure have been due to excessive breadth or insufficient thickness of augmentation.(12)
Capsulotomy and capsulorrahaphy are important steps in DDH primary and revision surgery. Incision of capsulotomy should be in T-shaped fashion, horizontal limb of T extends parallel to the acetabular rim medially inferior to the transverse ligament of the acetabulum and laterally as far posterior as possible, and the vertical limb should extend in the direction of piriform fossa, which facilitates full exposure of femoral head and neck (Fig 5).
During the capsulorrahaphy, the lower half of the capsule should be pulled and sutured in the direction of iliac bone to act as iliofemoral ligament, which has dual control of external rotation of the hip in flexion and both internal and external rotation in extension (13), and the upper half of the capsule should be pulled and sutured in direction of superior pubic ramus to function as pubofemoral ligament which has control of external rotation of the hip in extension (Fig 6).(13)
Tips and Tricks
1- List the possible reasons of failure of the primary surgery in preoperative note and address each one during the revision.
2- Once redislocation has occurred after primary open reduction, attempts to reduce the head by closed means or by pelvic or femoral osteotomy are usually unsuccessful and may prove harmful and lead to AVN; and a further open reduction Is necessary.(8)
3- Avoid the use of medial approach in revision surgery and older children due its poor visualization of the entire joint cavity, inability to perform a good capsulorrahaphy if there is an adhesion superiorly between the capsule and surrounding muscles that cannot be addressed adequately, and acetabular osteotomy cannot be done simultaneously (1)
4- Use carful sharp dissection for removal of the tough fibrous tissue, the remnants of the ligamentum teres and pulvinar to minimize future adhesions by eliminating bleeding. The transverse acetabular ligament has to be addressed and released adequately.
5- If derotation-varus shortening femoral osteotomy was planned with open reduction, capsular repair should be performed after fixation of the osteotomy.
6- During capsulorrahaphy suture tightening should be with increase tension starting from inferomedially to psoterolatrally to prevent the head from lateral subluxation with tight medial sutures and easy lateral sutures that pushes the head laterally.
7- Use of a non-threaded K-wire passing percutaneously from the greater trochanter to the pelvis avoiding the joint for temporary fixation of the reduction, while moving the patient to the spica table and application of the cast can be helpful to prevent dislocation during patient transfer. This K-wire should be removed after cast application.
8- Use threaded wire for fixation of acetabular osteotomy when needed to eliminate risk of osteotomy side collapse and graft slippage if necessary.
9- It is important to emphasize that, the revision surgery should not be attempted until the skin and soft tissues have softened up and hip motions have returned to prereduction ranges.(6)
Most cases that fail to obtain stable reduction at the initial operation were the result of errors in surgical technique or judgment . The many challenges that the surgeon faces exceed those posed by most primary surgeries for DDH.
A backup plan or a second line of surgical options should always be considered and ready in mind prior to surgery. Revision surgery for DDH can always improve function, but can rarely result in a normal joint (5,14), and this has to be communicated clearly to the family to avoid having angry parents postoperatively.
Lastly proper documentation is important in these cases; about preoperative, perioperative findings and the procedure performed for completion of the notes and to avoid medicolegal problems as in many of these cases the overall long-term clinical and radiological outcomes following revision are less than excellent. (2,5,6,10,8,15) It should be emphasized that revision for DDH is demanding and should not be carried out unless the requisite expertise in pediatric orthopedic surgery exists. A discussion of the case with a senior colleague can give further insight into the problem and possible solutions. At times referral of the case to the expert is a win-win situation.
Mousa M. Alhaosawi MD, SB-Ortho, SICOT. Dip Assistant Professor, Orthopaedic surgeon, Consultant Pediatric Orthopaedic and hip Surgeon, King Fahad Hospital, Almadinah Almunawwarah, Saudi Arabia firstname.lastname@example.org
Amir Shahriar Ariamanesh MD, BOA Overseas Fellow Assistant Professor, Orthopaedic surgeon, Consultant orthopaedic Hip & Knee Surgeon, Mashhad University of Medical Sciences, Iran email@example.com
Acknowledgements: None declared.
Financial disclosure: None declared.
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