Learn the Medial Approach Open Reduction hip (MAOR) surgical technique with step by step instructions on OrthOracle. Our e-learning platform contains high resolution images and a certified CME of the Medial Approach Open Reduction hip (MAOR) surgical procedure.
Medial approach open reduction (MAOR) was first described by Ludloff in 1908. Several variations have been described. This technique is a modification of the original with tenodesis of the ligament teres as described by Torode (JPO 2008). This operation is typically utilised for patients presenting between 6 and 18 months of age.
INCICATIONS.
The indication for MAOR is the dislocated hip that is either irreducible or unstable on attempted closed reduction. The procedure has been utilised from the age of 3 months up to 2 years but typically is used from 6 to 18 months.
SYMPTOMS & EXAMINATION.
This will depend on the age of the baby at presentation. Some patients have hip dysplasia diagnosed at or around birth either due to routine ultrasound screening because of risk factors (Breech presentation, positive family history). Some will have been detected using clinical screening (Positive Ortolani/Barlow manoeuvre, restricted abduction of hip). If presenting before 3 months of age patients should have trial of brace/harness treatment.
Older children often present at walking age when it is recognised that they have a limp and short leg.
INVESTIGATION.
Ultrasound is the investigation of choice before 6 months age. After this age ossification of the femoral head means that plain X ray of pelvis will be more appropriate. All patients should have arthrogram performed under general anaesthetic to determine whether closed reduction (+/- adductor tenotomy) and application of hip spica will be possible. If this is not successful then MAOR is indicated.
OPERATIVE ALTERNATIVES.
Anterior open reduction(AOR) is widely practiced as an alternative to MAOR. AOR has the advantage that reefing of the capsule can be performed to increase stability. In addition AOR can be combined with pelvic osteotomy. Therefore this is the preferred approach for children presenting after 18 months where residual acetabular dysplasia is unlikely to resolve.
MAOR has the advantage that it can be performed through a small incision and it is ideally suited to bilateral cases. The wounds heal with an excellent cosmetic result.
NON-OPERATIVE ALTERNATIVES.
There are no non operative alternatives for the irreducible dislocated hip. If the hip is severely dysplastic (acetabular index more than 40 degrees) and the child more than 12 months old, there is an argument that surgery should be delayed until 18 months so that combined AOR and pelvic osteotomy can be performed.
Surgery is performed under general anaesthesia. A single shot caudal epidural provides good pain relief for several hours post operatively. The patient is placed in a supine position at the bottom of the operating table with the surgeon sat at the end of the table and the assistant to his/her side. The affected leg should be draped free. Prior to formal skin prep an Opsite or similar drape is applied to cover the perineum. Some surgeons prefer to use operating loops to aid visualisation. Antibiotic prophylaxis should be broad spectrum since the operation is performed through the groin. Coamoxiclav is ideal with 2 further post operative doses.
Redislocation of the hip is possible and has been described in up to 5% of cases. The addition of the ligament trees tenodesis does reduce the risk. Most redislocations occur in the first 24 hours post surgery. Cross sectional imaging with either CT or MRI is mandatory and usually performed the first day post surgery prior to discharge. Most cases will be performed as an overnight stay.
Results of MAOR vary widely which may well reflect the several different variations and approaches that have been described. Good and excellent long term outcomes (Severin grade I/II) vary between 40-80%. AVN rates 5-43%. The results of our technique have been published (Torode et al 2008). We identified significant AVN (Grade II-IV) in 15% of patients. Transient ischaemic changes (grade I AVN) is not uncommon but does not seem to compromise long term outcome. If surgery is performed after 12 months of age the majority of patients will require a pelvic osteotomy as a secondary procedure since persistent acetabular dysplasia is the rule. The long term result however is very good (Bache et al, EPOS 2017).
References
Bache CE, Graham HK, Dickens DR, Donnan L, Jihnson MB, O’Sullivan M, Torode IP.
Ligamentum Teres tenodesis in medial approach open reduction for developmental dislocation of the hip. J Podiatry Orthop, 2008 Sep;28(6):607-13.
Morcuende JA, Meyer MD, Dolan LA et al.
Long-term outcome after open reduction through an anteromedial approach for congenital dislocation of the hip. J Bone Joint Surg Am. 1997;79(A):810-17.
Akilapa O.
The medial approach open reduction for developmental dysplasia of the hip: do the long-term outcomes validate this approach? A systematic review of the literature. J Child Orthop. 2014 Oct;8(5):387-97.
Reference
- orthoracle.com
