Abstract
Purpose
Pembersal acetabular osteotomy is a relatively less practised procedure for developmental dysplasia of hip in young children. We retrospectively studied the acetabular correction and clinico-radiological outcome with this osteotomy in 16 children (16 hips) aged less than 4 years.
Methods
Postoperative correction of acetabular dysplasia was measured by acetabular index (AI). At follow up, following radiological parameters were documented: Centre edge angle (CEA), Reimer's index (RI) and acetabular depth to width ratio (D/W ratio). Avascular necrosis of hip, stability, and premature fusion of triradiate cartilage (TRC) were also recorded. Overall containment was assessed by modified Severin classification and function by Mckay clinical grade.
Results
The mean age at time of surgery was 25 months. Mean follow up was 54 months. The postoperative AI (17.6 ± 5.6°) improved significantly from preoperative values (37.5 ± 5.0°) (p < 0.0001). Mean follow up AI on the operated side was 15.3 ± 6.9° as compared to 14.7 ± 4.4° on the normal side (p = 0.78). Follow up CEA (24.9 ± 11.3°), Reimer's index (14.3%), D/W ratio (40.9%) did not differ significantly from the normal side. Early closure of TRC was not found in any of hips. All hips were clinically stable. As per modified Severin's classification, 7 hips were Type Ia, 7 Type IIa and 2 had residual dysplasia. Twelve (75%) hips had excellent clinical outcome, 2 (12.5%) good outcome and 2 (12.5%) had fair outcome.
Conclusions
Pembersal osteotomy is a safe and effective option for correction of acetabular dysplasia during open reduction of DDH in young children. It improves the AI and femoral head coverage, and promotes formation of a congruent and stable hip joint.
Keywords: Developmental dysplasia of hip, Acetabular osteotomy, Acetabuloplasty, Pemberton, Pembersal
1. Introduction
Of the several problems one faces during the open reduction of development dysplasia of hip (DDH) in young children, acetabular dysplasia and instability remain the foremost. There are several methods available to address these issues. Some of the popularly used acetabular osteotomies for this purpose are Salter, Pemberton, Dega etc.
The Salter osteotomy is a transverse osteotomy of the ilium made just above the acetabulum and acts by opening the osteotomy anterolaterally by hinging and rotating the acetabular segment on the symphysis pubis.1 The osteotomy starts from the proximal portion of sciatic notch and emerges at or just above the anterior inferior superior iliac spine. Pemberton pericapsular iliac osteotomy was designed to hinge the acetabulum through the flexible triradiate cartilage.1 It initiates about 1 cm above the anteroinferior iliac spine. The cut is kept about 1–1.5 cm away from the attachment of the joint capsule. The osteotomy proceeds posteriorly and then inferiorly. At the distal end, the cut stays slightly anterior to the sciatic notch and ends into the triradiate cartilage.
The Morrissy in the ‘Atlas of Orthopedic Surgery’ described ‘Pembersal’ osteotomy as one in which the surgeon has not stayed within the ilium while performing the Pemberton osteotomy but rather broken into the sciatic notch before reaching the triradiate cartilage.1 Pembersal osteotomy was an inadvertent discovery made while performing Pemberton osteotomy.2 The discovery seemed advantageous since it permitted adjustment of orientation and somewhat shape of acetabular roof. The flexibility permissible with this osteotomy dissipated the need for femoral corrections in most cases.3 Because of its efficient mechanics, it was originally postulated for use in older children, dysplasias of hip due to various pathologies and revision procedures.2,3 However, Bursali et al. demonstrated its effective use as a primary acetabular procedure along with operative reduction of DDH in young children (<4 years).4 Despite the documented advantages of this osteotomy, the use of the osteotomy in practice has remained limited.2, 3, 4
We present our experience of managing such 16 young children (16 hips) with congenitally dislocated hips where this osteotomy was combined with open reduction of hip. The purpose was to get an insight into the acetabular correction and clinico-radiological outcome of the procedure.
2. Methods
The retrospective study (2010–2019) was carried out at a tertiary care pediatric centre and included patients who underwent Pembersal osteotomy combined with open reduction of hip joint for idiopathic developmental dysplasia of hip. The Institutional Ethics Committee approved the research (F.1/IEC/CNBC/15/02/2021/Protocol no.96/3657 dated 20/3/2021). We excluded patients with age >4 years, follow up less than 2 years and inadequate records. The procedures on bilateral dysplasia of hips are prone to have higher rate of avascular necrosis and worse surgical outcomes.5,6 Our series therefore included patients with unilateral dysplasia of hip to better appreciate the surgical outcome of the osteotomy and those with bilateral dysplasia were excluded. Patients with previous hip surgeries were also excluded. The clinical material in this series thus consisted of 16 children up to age 4 years with unilateral primary developmental dysplasia of hip where full documentation was available. Patient's/parent's permission was obtained to publish results.
2.1. Surgical technique
All hip were operated by the same principal surgeon. The surgical technique was a similar to that adopted by Tavares.3 The hip was approached thorough the bikini incision. The ilium was exposed subperiosteally using the iliofemoral approach. The sciatic notch was dissected to enable placement of blunt retractors. Further releases included transection of reflected head of rectus femoris and elevation of the straight head from the anterior inferior iliac spine. The iliopsoas tenotomy was carried out at the level of triradiate cartilage. A T shaped arthrotomy was utilized to debride the obstructions and inspect the interiors of joint and reduction. Labrum was routinely preserved. The hip stability was assessed using the criteria described by Zadeh et al.7 Pelvic osteotomy was considered for hips stable with axial loading in 30° of flexion and abduction. Femoral shortening was considered if it was felt that there was excessive pressure on the head when it is reduced. Post reduction, it should be possible to gently distract the femoral head away from the acetabulum for few millimetres without undue force.8 For our series, the shortening procedure was felt necessary for one hip only.
The pelvic osteotomy started approximately 1 cm above the anterior inferior iliac spine, followed the attachment of the joint capsule and the curve of acetabular dome and remained more anterior to the sciatic notch (Fig. 1). The osteotomy remained in the visible part of ilium near the sciatic notch to end at ilioischial line, just above the medial end of triradiate cartilage (TRC). The TRC was not violated and the hinge for acetabular modulation was symphysis pubis. It was a complete osteotomy and the lower portion of the pelvis was displaced anterior and inferior. Additionally, the acetabular roof was rotated laterally effectively reorienting the acetabular cavity. It is important to avoid any external rotation of the distal fragment to prevent retroverting the acetabulum. A triangular, curved graft harvested from anterosuperior part of ipsilateral ilium in a similar manner as described for Salter's osteotomy, was wedged into the osteotomy site and stabilized with Kirschner wires. The Kirschner wires were left buried under the subcutaneous tissues to prevent local skin irritation, migration and ensure a secure fixation till osteotomy united.
Fig. 1.
The extent of osteotomy (A,B) - The pelvic osteotomy started approximately 1 cm above the anterior inferior iliac spine, followed the attachment of the joint capsule and the curve of acetabular dome and remained more anterior to the sciatic notch. At the ilioischial line, the osteotomy ended just above the medial end of triradiate cartilage.
Post surgery, the reduction was verified radiologically and protected in a one and half spica for 3 months. After removal of spica, range of motion exercises were begun and weight bearing initiated as tolerated. The wires were removed post surgery 3–6 months after there was radiographic evidence of osteotomy union, under a short anesthesia. The child was prescribed a night time abduction orthosis for a further period of 6–9 months.
2.2. Evaluation
At follow up, the modified McKay's criteria was used for clinical evaluation of results.8 The results are considered excellent when hip is stable and painless with more than 15° of internal rotation present, there is no limp and Trendelenburg test is negative. Good results are considered when hip is stable and painless but slight limp and decrease in hip motion is present. Trendelenburg sign is still negative. A hip with positive Trendelenburg sign and moderate stiffness and presence of minimal pain is fair result. Present of significant pain qualifies the hip into poor results.
Radiographic evaluation was based on anteroposterior plain X-rays. Preoperatively, the severity of hip displacement was assessed using Tonnis grade (Grade 1: The cartilaginous head of femur is lateral displaced no more than two third of its width judged in relation to the superior rim of the acetabulum; Grade 2: The head is displaced laterally by more than two third of its width; Grade 3: The head is displaced upwards by more than one third of its height relative to the cartilaginous rim of the acetabulum; Grade 4: The head is completed dislocated).9 Acetabular index (AI) was calculated for both sides in preoperative radiographs. A postoperative AI evaluation was carried to record surgical correction of dysplasia. In subsequent follow up radiographs, acetabulum was evaluated for presence of dysplasia, containment and premature fusion of TRC. Radiological parameters calculated were AI, centre edge angle (CEA), Reimer's index (RI) and acetabular depth to width ratio (D/W ratio).10, 11, 12, 13 Overall containment was assessed by modified Severin classification.14 Severin class I and II are considered favorable whereas classes III, IV, V and VI are considered unfavourable.15 The avascular necrosis of hip (AVN) was documented by Kalamchi and MacEwen's classification.16
2.3. Statistical analysis
The preoperative Tonnis grade, Mckay clinical grade, Severin class and AVN classification were descriptive. The statistical analysis was done on the online ‘MedCalc’ statistical software. Preoperative AI on both sides was compared using paired student t-test to determine the approximate preoperative dysplasia on affected side. The preoperative AI was compared to post operative AI at 3 months (at removal of spica) on the operated side to study the effect of surgical correction. AI, CEA, D/W ratio and Reimer's index of operated side were compared to normal side on final follow up to determine long term results of surgical restoration. P values of <0.05 were considered significant.
3. Results and observations
The patient details are mentioned in Table 1. The mean age at the time of surgery was 25 months (range, 16–47 months). There were 4 males and 12 females in our study. The initial Tonnis grade was IV in 8, 4 each of III and II. Only one patient required additional varus derotation and shortening of proximal femur. Mean total follow up was 54 months (range, 24–120 months). Mean patient's age at final follow up was 78.9 ± 25.7 months (range, 40–137 months).
Table 1.
Clinical and radiological results of Pembersal osteotomy for DDH in young children (hips = 16).
| Preoperative |
Early post operative |
Follow up |
||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Patient's age (months) | Tonnis grade | AI (degrees) normal side | AI (degrees) affected side | AI (degrees) affected side | Duration (months) | Patient's age (months) | AI (degrees) normal side | AI (degrees) affected side | CE angle (degrees)normal side | CE angle (degrees) affected side |
Reimer's index (%) normal side | Reimer's index (%) affected side | D/W ratioa (%) normal side |
D/W ratioa (%) affected side | Modified Severin Class affected side |
Mckay clinical criteria |
| 36 | IV | 18 | 47 | 22 | 24 | 60 | 14 | 18 | 26 | 20 | 0 | 9.4 | 40.9 | 44.8 | Ia | Excellent |
| 25 | III | 21 | 38 | 10 | 48 | 73 | 14 | 8 | 30 | 36 | 0 | 12.7 | 44.6 | 36 | Ia | Excellent |
| 47 | IV | 19 | 40 | 28 | 77 | 124 | 17 | 17 | 31 | 22 | 0.1 | 29.6 | 51.8 | 46.2 | Ia | Excellent |
| 19 | IV | 26 | 35 | 16 | 62 | 81 | 19 | 9 | 27 | 27 | 0 | 11.4 | 49.6 | 52 | Ia | Excellent |
| 17 | II | 20 | 32 | 21 | 75 | 92 | 15 | 11 | 20 | 33 | 0.2 | 11.2 | 44 | 48.6 | Ia | Excellent |
| 37 | III | 21 | 39 | 22 | 54 | 91 | 10 | 11 | 30 | 29 | 0.2 | 13.6 | 40.7 | 36.3 | Ia | Excellent |
| 17 | III | 20 | 29 | 15 | 120 | 137 | 12 | 21 | 25 | 15 | 0.2 | 29.8 | 43.1 | 41.2 | Ia | Excellent |
| 18 | IV | 27 | 40 | 14 | 62 | 80 | 13 | 17 | 42 | 33 | 0 | 0 | 40.5 | 36.6 | IIa | Good |
| 24 | IV | 20 | 41 | 12 | 24 | 48 | 17 | 11 | 20 | 27 | 0.1 | 0 | 40.2 | 40.8 | IIa | Excellent |
| 23 | II | 27 | 33 | 21 | 42 | 65 | 15 | 7 | 30 | 32 | 0.1 | 0 | 32.1 | 42.2 | IIa | Excellent |
| 26 | IV | 27 | 45 | 21 | 66 | 92 | 17 | 12 | 27 | 40 | 0 | 0 | 43.5 | 48.3 | IIa | Excellent |
| 16 | III | 26 | 39 | 26 | 24 | 40 | 20 | 19 | 21 | 15 | 0.1 | 24.6 | 35 | 37.2 | IIa | Fair |
| 17 | II | 17 | 30 | 8 | 69 | 86 | 14 | 9 | 33 | 39 | 0 | 0 | 48 | 43.7 | IIa | Excellent |
| 35 | IV | 10 | 34 | 15 | 25 | 60 | 9 | 16 | 34 | 23 | 0 | 0 | 45.9 | 35.1 | IIa | Excellent |
| 16 | II | 20 | 40 | 17 | 63 | 79 | 16 | 32 | 15 | 5 | 0.2 | 43.8 | 37.4 | 30.8 | III | Good |
| 25 | IV | 20 | 38 | 14 | 30 | 55 | 14 | 26 | 24 | 2 | 0.1 | 43 | 38.7 | 34 | III | Fair |
D/W ratio-acetabular depth to width ratio.
The mean preoperative AI was 37.5 ± 5.0° and differed significantly from 21.2 ± 4.6° on the normal side (p < 0.0001). The postoperative AI (17.6 ± 5.6°) improved significantly from preoperative values (p < 0.0001) (Fig. 2). The postoperative AI matched that of normal side indicating a restored acetabular coverage (p = 0.234). Mean follow up AI on the operated side was 15.3 ± 6.9° and 14.7 ± 4.4° on the normal side (p = 0.78) (Fig. 2). Mean CEA at follow up was 24.9 ± 11.3° on operated as compared to normal side where it was 27.2 ± 6.5° (p = 0.48). Mean Reimer's index on the operated side (14.3%) matched normal side (9.1%) at final follow up (p = 0.65). The mean D/W ratio at final follow up was 40.9% on affected side and 42.3% on the normal side (p = 0.93).
Fig. 2.
A. The left hip of the patient was operated at age 25 months (patient 3). The preoperative Tonnis grade was III. B. A triangular, graft harvested from ipsilateral ilium was wedged into the osteotomy site and stabilized with Kirschner wires. The preoperative AI of the affected side (38°) corrected to 10° postoperatively. C. At follow up of 48 months, the AI of the operated side was 8°, CE was 36°, Reimer's index was 12.7% and D/W ratio was 36%. The hip function was excellent and Severin grade was Ia. There was no AVN during the course of follow up and TRC was still open.
We encountered no re-dislocations. There were no infections and no graft displacements. Early closure of TRC was not found in any of the hips at follow up. AVN was present in two hips during the follow up that were all asymptomatic. One was grade II, whereas other was grade IV according to Kalamchi and MacEwen's classification. As per modified Severin's classification, 7 hips were Type Ia, 7 Type IIa and 2 had residual dysplasia (Type III). All hips were clinically stable with no telescopy. Twelve (75%) hips had excellent clinical outcome, 2 (12.5%) good outcome and 2 (12.5%) had fair outcome.
4. Discussion
4.1. Principal findings
We utilized a modified version of Pembersal osteotomy which avoided transecting TRC (Fig. 1). This complete osteotomy permitted extensive modularity of acetabular coverage in terms of anterior and lateral displacement as well as rotation through pliable pubis symphysis. Another advantage of the osteotomy was that it avoided the medial displacement of the distal fragment, a potential complication possible with Salter's osteotomy.17 The superior fragment spike posteriorly at the ilioischial line prevented this displacement in Pembersal osteotomy. The osteotomy passed through the portion of ilium having the maximum thickness and dense metaphyseal bone, so there were no concerns for graft contact or union. The graft size could be controlled to maintain osteotomy displacement. The graft required fixation in a manner similar to Salter's osteotomy.
We could quantitatively demonstrate the useful effect of surgical reduction and the Pembersal osteotomy on hip development. Acetabular dysplasia associated with DDH in young children could be effectively corrected with the osteotomy when used in conjunction with open reduction. There was no alteration in shape of the acetabulum or decrease in its capacity following osteotomy as TRC was not manipulated. A femoral shortening osteotomy was not done in all but one patient with acceptable results. The osteotomy was conducive to natural long term growth of acetabulum by permitting remodelling and normalizing radiological parameters at par with normal side on follow up. The osteotomy had a low complication rate in our series.
4.2. Comparison with literature
Perlik et al., in 1985 described a combination of Salter and Pemberton osteotomies for correction of acetabular dysplasia in children.2 This procedure came to be known as Pembersal osteotomy or modified Pemberton acetabuloplasty.2, 3, 4 The osteotomy offered better modularity in terms of acetabular reorientation. A comparison of outcome in various series using Pembersal technique is presented in Table 2.
Table 2.
Review of series using Pembersal osteotomy.
| Author | Description of medial extent of osteotomy | Patient age (years) | Number of patient (hips) | Combined with primary open reduction of DDH (hips) | Preoperative/follow up AI (degrees) | Follow up CE (degrees) | Follow up (years) | TRC closure (hips) |
|---|---|---|---|---|---|---|---|---|
| Perlik et al., 1985 | Through the ilioischial limb of TRC, deep into body of ishium | 7.3 | 44 (50) | – | 20.7/14.4 | 36.4 | 6 | – |
| Tavares, 2004 | The cut ended more anterior than the sciatic notch just after the osteotome crossed the iliopectineal line; no attempt was made to reach the posterior limb of TRC. In some cases it may have propagated into TRC | 6 | 16 (17) | 4 | 33.5/10.6∗ | 33∗ | >4 | 2 |
| Bursali and Tonbul, 2008 | Osteotomy continued through the ilioischial limb of TRC but not through the distal cortex | 5 | 33 (44) | 44∧ | 37.6/12.5$ | 29.1 | >5 | 8 |
| Current series | The cut ended just close to the medial end of TRC | 2.1 | 16 (16) | 16 | 37.5/15.3 | 24.9 | 4.5 | – |
CE-centre edge angle; TRC-triradiate cartilage; DDH-developmental dysplasia of hip; ∗postoperative AI and CE values; $Acetabular roof obliquity; ∧22 hips were in children less than 4 years old.
Despite the benefits, the series using this osteotomy are limited in literature.2, 3, 4 Possible reasons include original description of the osteotomy recommending its use exclusively for dysplasias of various pathologies, subluxations, redos, and relatively older children.2, 3, 4 Some series stigmatized this osteotomy for TRC closure. In the Tavares et al. series, there was TRC closure in 2 hips (2/17,11.8%) and for Bursali's series, it occurred in 8 hips out of 44 hips (18%).3,4 It is prudent to mention here that both series attributed this complication to violating the TRC in a relatively older age group or during an early experience with the osteotomy. In fact, when the osteotomy was used for younger children with DDH (<4 years), the radiographic results (acetabular roof obliquity, CEA) were far better restored and there were no redislocations, graft displacements or infections. The authors inferred that the osteotomy may be better suitable for younger children than older children.4
Concomitant acetabular osteotomy is a recommended procedure to ensure stability and correction of dysplasia in children (12 months of age and beyond) with DDH.5 Several types of acetabular osteotomies are available for this purpose. Mean post operative improvement in AI following Salter, Pemberton and Dega acetabular osteotomies in young children has been reported in the range of 20–40%.18,19 For our series, postoperative AI following Pembersal osteotomy corrected to the tune of 53% [(37.5–17.6)/37.5°]. The radiological congruity as per Severin score reported with Salter, Pemberton and Dega osteotomy is 84%, 91.2% and 84% respectively.15 For our series with Pembersal osteotomy, it was 87.5%. Thus, the Pembersal osteotomy appears to be at par or superior to above acetabular osteotomies in quantitative terms of restoring acetabular dysplasia and congruity.
Our study results correlated well with the only other predominant study by Bursali et al. using Pembersal osteotomy for exclusively for DDH.4 The radiological parameters for the subgroup with 22 hips operated in young children were (preoperative AI: 38.77°; follow up acetabular obliquity index 10.7°; follow up CE: 30.5°; follow up Reimer's index 0.16; follow up D/W ratio 42.14). The Severin class was I for 7 hips, II for 14 and one hip was class III. The clinical results were excellent to good in 19 (86.4%) hips and fair in 3 hips.
Our experience with Pembersal osteotomy had been quite encouraging. Although an exact quantitative matching with other acetabular osteotomies was not possible, the improvement in radiological parameters and clinical function achieved at follow up (Table 1) speak for the efficiency of this osteotomy. The low complication rate (including no TRC closures) further complimented the clinicoradiological outcome.
4.3. Clinical implications
Pembersal osteotomy was originally promoted as an option for hip dysplasias in older children. Our study provided evidence of Pembersal osteotomy being an effective acetabular option for DDH in young children. The experience with this particular osteotomy is still limited and it will be worthwhile to have more centres report long term outcome with this procedure. The risks associated with the Pembersal osteotomy are probably due to different extent used in various series and sometimes the learning curve associated with the procedure.2, 3, 4 Most of the complications are attributed to violation of TRC. However, Pemberton osteotomy extends right to the TRC and has potential for similar damage.20 Further our modification of technique did not intrude TRC. Thus, there seems no reason to condemn Pembersal on these grounds. Rather advantage should be taken of the useful aspects of the osteotomy: modularity of the acetabular orientation possible, large contact area, easy fixation and inherent stability. A potential disadvantage may include the need for repeat operation to remove pins.
4.4. Limitations
All of our children were skeletally immature at final follow up. As such, the development of proximal femur and acetabulum was still in progress and final clinical and radiological results may change at maturity. Other limitations were a retrospective study design, different ages at which open reduction was performed, and the dissimilar follow up period. The preoperative Tonnis grade and acetabular dysplasia were of different severity. The plain radiographs formed the basis of both initial and serial evaluation. Further, it was beyond the scope of this study to make a comparison between different acetabular osteotomies, and values from literature formed the basis for comparison. Although the current report was related to Pembersal osteotomy, the preferred osteotomy in DDH should be decided on case to case basis and the experience of the surgeon.
4.5. Strengths
Strengths included a series of unilateral DDH cases operated with a common technique. All cases were operated by a single surgeon ensuring uniformity of the procedure. The patient numbers was robust and follow up > 2 years was available for most cases.
5. Conclusions
Pembersal osteotomy is a safe and effective option for correction of acetabular dysplasia during open reduction of DDH in young children. It improves AI and femoral head coverage and promotes formation of a congruent and stable hip joint.
Funding
There is no funding source.
Declaration of competing interest
The authors declare that they have no conflict of interest.
Contributor Information
Anil Agarwal, Email: anilrachna@gmail.com.
Prateek Rastogi, Email: prateek.rastogi12@gmail.com.
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