Femoral Derotation Research Articles

Superior functional outcome after femoral derotation osteotomy according to gait analysis in cerebral palsy

The femoral derotation osteotomy (FDO) is seen as the golden standard treatment in children with cerebral palsy and internal rotation gait. Variable outcomes with cases of over- and undercorrection mainly in the less involved patients have been reported. The determination of the amount of derotation is still inconsistent. 138 patients (age: 11 (±3.3) years) with cerebral palsy and internal rotation gait were examined pre- and 1 year postoperatively after distal or proximal FDO, using standardized clinical examination and 3D gait analysis. Three groups were defined retrospectively depending on the amount of derotation in relation to the mean hip rotation in stance (MHR) during gait analysis: Group A (derotation angle > MHR+10°), Group B (derotation angle=MHR±10°), Group C (derotation angle <MHR−10°), and compared according to their postoperative mean hip rotation. ANOVA with Bonferroni post hoc test was used for statistics (p<0.05). Group B had the greatest benefit with the highest rate (86%) of good results (postoperative MHR=±15°). In contrast there were 14% cases of overcorrection and 5% cases of deterioration in Group A with only 81% good results and only 79% good results in Group C. It can be concluded, that it is less likely to have unsatisfactory outcomes if the amount of FDO is defined according to the findings of gait analysis compared with clinical examination.

The outcome after femoral derotation osteotomy in cerebral palsy depends on the treatment strategy

Introduction and aim: Internal rotation gait is common among children with cerebral palsy. Despite the underlying cause is still not fullyunderstood, femoral derotationosteotomy (FDO) is seenas the golden standard treatment. Various studies reported the effectivenessof thisprocedure to correct internal rotationgait.However, some authors reported variable outcome after FDO, especially in cases with mild involvement [1]. One problem in the treatment of internal rotation gait is how to determine the amount of intraoperative derotation. It is often determined by clinical passive range of motion, despite a dynamic disorder is intended to treat. A major question is if outcome becomes more predictable when derotation amount is determinedaccording todata fromgait analysis. Thepurpose of this study was to evaluate if patients in which derotation amountwas close tomeanhip rotation in gait analysis have a better predictable outcome than those inwhichderotation amount differs from dynamic data. Patients/materials and methods: 162 patients (293 legs) aged 12.3±6.4 yrs that all underwent FDO were retrospectively collected in two clinical centers. Inclusion criteria were availability of gait data both preand one year postoperatively and a documentation of the amount of intra-operative derotation measured with derotation wires. The derotation amount ranged between 25◦ internal and40◦ external. Patientswereclassified into threegroups: (A) Excessive FDO with derotation amount more than 5◦ larger than indicated by mean hip rotation in stance, (B) Moderate FDO with derotation amount within ±5◦ of gait data indication, and (C) Conservative FDO with derotation amount more than 5◦ less than indicated by mean hip rotation in stance. Improvement in mean hip rotation in stance was calculated by subtracting postoperative from preoperative mean hip rotation in stance. Results: Theaverage improvementwas12.2◦ in thegroupExcessive FDO, but 30/142 patients (21%) deteriorated. The Moderate FDO group had the greatest benefit (18.5 degrees of improvement) and an improvement in 89/99 (90%) patients. The average improvement in the Conservative FDO group was 20.5 degrees but under-correction was found in some patients (Fig. 1). Discussion and conclusions: The results of this study suggest that the derotation amount should be determined according to mean hip rotation in stance in order to receive a good dynamic outcome. If the amount of derotation differs largely from gait data, overandunder-correctionare tobeexpected. Since femoral anteversion and clinical exam only partially reflect dynamic hip function during gait [1,3], these parameters should mainly be considered to avoid overcorrection into retroversion and not to determine the amount of derotation

Unexpected angular or rotational deformity after corrective osteotomy.

BackgroundCodman’s paradox reveals a misunderstanding of geometry in orthopedic practice. Physicians often encounter situations that cannot be understood intuitively during orthopedic interventions such as corrective osteotomy. Occasionally, unexpected angular or rotational deformity occurs during surgery.This study aimed to draw the attention of orthopedic surgeons toward the concepts of orientation and rotation and demonstrate the potential for unexpected deformity after orthopedic interventions. This study focused on three situations: shoulder arthrodesis, femoral varization derotational osteotomy, and femoral derotation osteotomy.MethodsFirst, a shoulder model was generated to calculate unexpected rotational deformity to demonstrate Codman’s paradox. Second, femoral varization derotational osteotomy was simulated using a cylinder model. Third, a reconstructed femoral model was used to calculate unexpected angular or rotational deformity during femoral derotation osteotomy.ResultsUnexpected external rotation was found after forward elevation and abduction of the shoulder joint. In the varization and derotation model, closed-wedge osteotomy and additional derotation resulted in an unexpected extension and valgus deformity, namely, under-correction of coxa valga. After femoral derotational osteotomy, varization and extension of the distal fragment occurred, although the extension was negligible.ConclusionsSurgeons should be aware of unexpected angular deformity after surgical procedure involving bony areas. The degree of deformity differs depending on the context of the surgical procedure. However, this study reveals that notable deformities can be expected during orthopedic procedures such as femoral varization derotational osteotomy.

Biplanar supracondylar femoral derotation osteotomy for patellofemoral malalignment: the anterior closed-wedge technique.

Patellofemoral malalignment can be caused by several factors including increased internal torsion of the femur. As a causative treatment method, supracondylar femoral derotation osteotomies have been proposed. For valgus- and varus-producing supracondylar femoral osteotomies, a biplanar osteotomy has been introduced in order to enhance primary fixation stability and osseous consolidation by increased bone-to-bone contact. In this article, a modification of this technique is described, which allows for a biplanar supracondylar femoral derotation osteotomy. V.

One stage surgery using subtrochanteric osteotomy versus two stage surgery using supracondylar femoral derotation osteotomy in treatment of developmental dysplasia of the hip joint for older children

Background: The one stage surgery of open reduction and subtrochantric femoral osteotomy with or without pelvic osteotomy, has been an accepted method of treatment of congenital hip dislocation in older children. This approach obtains predictable reduction and results in a low rate of osteonecrosis despite the higher rate of operative and postoperative morbidity like prolonged anesthesia time, large incisions and more immediate postoperative complications. Two-stage surgery might, therefore, help in avoiding the above-cited disadvantages. Aim of the study: Is to compare the results obtained by using either one-stage surgery by subtrochanteric or two-stage surgery by supracondylar femoral derotational osteotomies in the management of developmental dysplasia of the hip joint. Patients and Methods: This is a randomized controlled trial involving children under the age of 2.5 years with developmental dysplasia of the hip and attending Basrah General Hospital between December 2010 till August 2012. Thorough clinical examination and laboratory investigations were done for all the patients and only 30 patients with 39 dislocated hips whom did not require femoral shortening and need >10-15 degrees of acetabular roof index correction using pelvic osteotomy were included in this study. Each patient was randomly allocated into one of the two surgical procedures; procedure A was one-stage surgery and procedure B was two-staged surgery. At the end of the study period, a total of 30 patients under the age of 2.5 years were recruited for this study, 16 patients underwent procedure A and another 14 underwent procedure B. The patients were followed-up for 12-18 months and evaluated clinically & radiologicaly depending on McKay and Severin’s clinical and radiological criteria respectively. Results: Thirty patients with 39 dislocated hips were managed. Patients age ranged from 1.5 to 2.5 years; all of them were females having no associated skeletal anomaly. The outcome of one-stage surgery showed better clinical (78.9%) and radiological results (88.8%) in comparison to two-stage surgery which showed 45% clinical and 70% radiological results, however, the time of technical procedure and other morbidities for example; risk of infection (20%), preoperative blood transfusion (100%), respiratory distress (13.5%) were relatively greater in one-stage surgery. Conclusion: The results of this study showed that one-stage operation resulted in better joint realignment, without increasing risk of avascular necrosis, and more hip joint physiological and anatomical remodeling affinities, despite of its prolonged time and more rate of immediate postoperative morbidity. While in the two-staged surgery, the clinical and radiological outcomes were less successful than those with one-stage operation, though immediate postoperative morbidities were less.

Do changes in torsional magnetic resonance imaging reflect improvement in gait after femoral derotation osteotomy in patients with cerebral palsy?

Femoral derotation osteotomy (FDO) is commonly used to correct internal rotation gait (IRG) in spastic diplegia. The purpose of this study was to investigate whether the extent of intraoperative derotation is reflected in changes in static (clinical ROM and anteversion angle measured on torsional MRI) and dynamic parameters (transverse plane kinematics in three-dimensional gait analysis) after FDO in children with spastic diplegia. In a prospective study, 30 children with spastic diplegia and IRG were treated with FDO as part of a multilevel surgery and were examined pre- and postoperatively clinically, by three-dimensional gait analysis and by torsional MRI according to a standardised protocol. A correlation (r = 0.317, p = 0.015) between the extent of intraoperative derotation and mean hip rotation in stance as well as the anteversion angle measured on torsional MRI (r = 0.454, p < 0.001) was found. However, no significant correlation was observed between anteversion angle (tMRI) and mean hip rotation in stance, either before or after FDO. Significant improvements were found in IRG after FDO, confirming the results of previous studies. There was no correlation between the anteversion measured on MRI and the mean hip rotation in stance in 3D gait analysis before or after FDO. Thus, the data suggest that if the intraoperative extent of derotation is determined only by the anteversion angle, the result will not be better after FDO. It might only help to avoid retroversion and indicate the maximum amount of femoral derotation. In this study the extent of the intraoperative derotation was orientated at the preoperative midpoint of rotation. Based on the small, but significant correlation between the clinical midpoint and the mean hip rotation in stance in the gait analysis, determination of the intraoperative extent of derotation according to the mean hip rotation in stance seems to give the best results.

Impact of gait analysis on correction of excessive hip internal rotation in ambulatory children with cerebral palsy: a randomized controlled trial

The aim of this study was to determine if gait analysis improves correction of excessive hip internal rotation in ambulatory children with spastic cerebral palsy (CP). Children undergoing orthopedic surgery were randomized to receive or not receive a preoperative gait analysis report. This secondary analysis included all participants whose gait report recommended external femoral derotation osteotomy (FDRO). One-year postoperative, and pre- to postoperative change in femoral anteversion, mean hip rotation in stance, and mean foot progression in stance were compared between groups and in subgroups based on whether the recommendation for FDRO was followed. Outcomes did not differ between the group which received a gait report (n=39; 19 males, 20 females; mean age 10y 4mo [SD 3y]; hemiplegia, 3; di/triplegia, 28; quadriplegia, 8; Gross Motor Function Classification System [GMFCS]: level I, 5; level II, 12; level III 19; level IV, 3) and the control group (n=26; 14 males, 12 females; mean age 9y 5mo [SD 2y 10mo]; hemiplegia, 1; di/triplegia, 21; quadriplegia, 4; GMFCS: level I, 4; level II, 1; level III, 9; level IV, 2; all p values >0.29), but improved more in the gait report subgroup in which the FDRO recommendation was followed (seven limbs; change in anteversion -32.9°, hip rotation -25.5°, foot progression -36.2°) than in the control group (anteversion -12.2°, hip rotation -7.6°, foot progression -12.4°; all p values ≤0.02) and the gait report subgroup in which FDRO was not performed (32 limbs; anteversion -1.0°, hip rotation 0.5°, foot progression -8.0°; all p values ≤0.003). Postoperative measures became normal only in the gait report subgroup in which the recommended FDRO was performed. Gait analysis can improve outcomes when its recommendations are incorporated in the treatment plan.

Short-term effects of proximal femoral derotation osteotomy on kinematics in ambulatory patients with spastic diplegia

The aim of this retrospective study was to determine the short-term effects of proximal femoral derotation osteotomy (FDO) on gait in 53 ambulatory patients with spastic diplegia controlling all confounding procedures. All patients showed a jump gait pattern and had undergone bilateral rectus femoris transfer, distal hamstring lengthening, and tendo-Achilles lengthening as a single-event multilevel surgery. Of these, additional bilateral proximal FDOs were included in 25 patients, defined as the FDO group; the other 28 patients were defined as the no-FDO group. Kinematic variables, such as pelvic tilt, minimal hip flexion in stance, hip rotation, and foot progression angle, were compared between the two groups at postoperative 1 year. Hip extension, hip rotation, and hip adduction improved significantly after surgery in the FDO group (P<0.001, P=0.004, P=0.028), but not in the no-FDO group. Foot progression angle improved in both groups, but the degree of improvement was significantly greater in the FDO group (P=0.004). In conclusion, FDO improved hip rotation, hip adduction, and hip extension as well as foot progression angle in the ambulatory patients with spastic diplegia showing a jump gait.

An Experimental Setup for Instrumental Analysis of Femoral Derotation Osteotomy

Article An Experimental Setup for Instrumental Analysis of Femoral Derotation Osteotomy was published on September 7, 2013 in the journal Biomedical Engineering / Biomedizinische Technik (volume 58, issue SI-1-Track-M).

Children’s orthopaedics

The October 2012 Children’s orthopaedics Roundup360 looks at: magnetic growing rods and scoliosis correction; maintaining alignment after manipulation of a radial shaft fracture; Glaswegian children and swellings of obscure origin; long-term outcome of femoral derotation osteotomy in cerebral palsy; lower-leg fractures and compartment syndrome in children; fractures of the radial neck in children; management of the paediatric Monteggia fracture; and missing the dislocated hip in Western Australia.

Surgical treatment of hip dislocation in Kabuki syndrome: Use of incomplete periacetabular osteotomy for posterior acetabular wall deficiency

Kabuki syndrome is characterized by distinctive facial features, skeletal anomalies, persisting fingertip pads with dermatoglyphic abnormalities, postnatal growth deficiency and mental retardation. This report reviews our results in the operative treatment of hip dislocations in patients with Kabuki syndrome. Between 2001 and 2009, seven dislocated hips (three unilateral and two bilateral hips) in five patients (all girls) were operatively treated at our institution. The operative treatment consists of open reduction, femoral derotation varus osteotomy, pelvic osteotomy (Salter in one and incomplete periacetabular osteotomy in six hips) and capsular plication. The age of the patients at the time of surgery ranged from 2.4 to 5.7years, with an average of 3.6years. The follow-up postoperative period ranged from 3.2 to 6.3years, with an average of 5.0years. At the final follow-up, all patients reported no click and no pain, and showed well-contained hips by radiographs. All seven hips were graded as Severin class I-II. One patient presented as having habitual dislocation of the hip 4.4years after surgery. Computed tomographic (CT) scans revealed posterior acetabular wall deficiency, which was not corrected by the anterolaterally directed Salter osteotomy. The incomplete periacetabular osteotomy provided sufficient posterolateral coverage of the acetabulum. Operative treatment combining open reduction, femoral derotation varus and incomplete periacetabular osteotomies, and capsular plication provided successful results in patients with Kabuki syndrome who had the characteristics of hip instability such as ligamentous laxity, muscular hypotonia and posterior acetabular wall deficiency.

Long-term outcome of femoral derotation osteotomy in children with spastic diplegia

Satisfactory short-term results after femoral derotation osteotomy (FDO) for the treatment of internal rotation gait in cerebral palsy have been reported by various authors. However, there are only a few longer-term studies reporting results 5years after FDO and these are not in agreement. There are no reports on the clinical course beyond the pubertal growth spurt. 33 children with diplegia (n=59 legs, age: 10.5±3.6years) and internally rotated gait were examined pre- (E0), 1year (E1), 3±1 (E2) and 9±2 (E3)years after distal (27 legs) or proximal (32 legs) FDO as part of multilevel surgery, using standardized clinical exam and 3D gait-analysis at all examinations. The amount of intra-operative derotation averaged 25°. ANOVA was used for statistics (p<0.05). Mean hip internal rotation in stance at E0 of 17.3° was significantly changed to 1.0° of external rotation at E1 and was maintained at 4.2° at E3. The same clinical course was found for foot progression angle. The mid-point of passive hip rotation at E0 was 21°. This was significantly decreased to 6° at E1 and showed a small but significant increase reaching 12° at E3. The results of this study showed a good overall correction of internally rotated gait following FDO. These improvements were maintained at long-term follow-up after the pubertal growth spurt. Recurrence was observed in some cases with overall severe deterioration. In those patients persistent dynamic factors leading to recurrence should be further investigated.

Long-term outcome of femoral derotation osteotomy in spastic diplegia

Long-term outcome of femoral derotation osteotomy in spastic diplegia

Comment on Jia et al.: Three dimensional CT evaluation of femoral neck anteversion, acetabular anteversion and combined anteversion in unilateral DDH in an early walking age group

With great interest we read the article, “Three dimensional CT evaluation of femoral neck anteversion, acetabular anteversion and combined anteversion in unilateral DDH in an early walking age group” by Jia et al. [1], published in your esteemed journal International Orthopedics. First of all, we would like to congratulate the authors for an excellent study. However, we would like to raise a few points which need further clarification. The analysis of the data showed no statistically significant difference between dislocated and normal hips in relation to FA (p-value 0.071) (Table 1). But subgroup analysis showed a statistically significant difference in the Tonnis IV group (p-value 0.028) (Table 2). The sample size is not so large (hence non parametric tests applied for statistical analysis), so that in such conditions with further sub group analysis, there is a chance of statistical exaggeration of the difference. If we critically look at the FA (dislocated side) in the various subgroups of Tonnis II (32.53 ± 6.86°), Tonnis III (34.79 ±7.02°) and Tonnis IV (35.97 ±10.24°), the difference among these groups might not be significant. Hence we feel that the authors' recommendation that femoral derotation may be needed if the CA is above 62° holds for all cases irrespective of Tonnis grade, as this might also happen in Tonnis grades II or III. At the same time we are eager to know the results of the surgery in these patients from the author, as this will further strengthen their views. In our experience of 15 cases, there was no need for femoral derotation in any of them [2]. As DDH is a condition where acquiring a huge sample size is difficult we need many more studies including preoperative evaluation, intraoperative assessment and postoperative radiological reassessments.

Comparison of two techniques in achieving planned correction angles in femoral subtrochanteric derotation osteotomy

Increased femoral anteversion in cerebral palsy alters biomechanics of gait. Femoral subtrochanteric derotational osteotomies are increasingly performed to improve gait in cerebral palsy. The amount of angular correction can be determined and planned preoperatively but, accuracy in achieving planned angular correction has not been tested experimentally before. The aim of this study was to evaluate the accuracy of the two techniques in achieving planned angular correction. Sixteen dry femora were used in this study. Specimens in both groups were derotated to achieve a desired amount of correction with two different techniques, consecutively. In technique one, the cross section of the femur was assumed to be circular and the desired amount of angular correction was calculated and expressed in terms of surface distance by a geometric formula (surface distance=2×π×radius of femur). In both groups, derotations were made based on this surface distance calculation. Consecutively the same specimens were derotated by pins and guide technique. Femoral anteversion of specimens were measured before and after derotation by computerized tomography. There was a statistically significant differance in planned and achieved correction angles (P=0.038) in both subgroups derotated by the surface distance technique. When the two techniques were compared, there was significant difference (P=0.050) between high magnitude correction subgroups (subgroups 2 vs. 4). In conclusion, the results of this study highlighted the difficulty in achieving accurate derotation angles. Derotations based on guide-pins technique yielded more accurate results than derotations based on surface distance technique. In addition, surface diameter technique was not suitable when higher degrees of derotations are needed. In achieving a planned derotation angle two techniques are described for accuracy. Both the techniques have potential pitfalls resulting in malrotations. Surgeons must be aware of these obstacles and try to avoid them.

Neglected, developmental hip dislocation treated with external iliofemoral distraction, open reduction, and pelvic osteotomy

Between 1995 and 2003, we operated upon 18 children with 20 hips involved, aged 5-11 years (average: 7.5 years) suffering from an inveterate high developmental dislocation of the hip joint. An average follow-up period of our middle-term study was 51 months (range: 34-96 months). A two-staged management was applied. First, femoral head was lowered back to the level of acetabulum with an external fixator or a distractor device. The second stage involved open reduction combined with pelvic osteotomy and, in four cases with femoral derotation osteotomy. We noted two cases of avascular necrosis. Equal limb length was achieved in 15 cases. There were two cases of 0.5-cm length discrepancy, two cases of 1-cm length inequalities, and one case of 5-cm limb shortening. We endorse this method in neglected cases of previously untreated unilateral high developmental hip dislocations in children aged 8-10 years. It results in a usable hip joint without the need of femoral shaft shortening and facilitates future joint replacement.

Outcomes of correction of internal hip rotation in patients with spastic cerebral palsy using proximal femoral osteotomy

Internal hip rotation (IHR) is the major cause of intoeing gait in patients with cerebral palsy (CP). Femoral derotation osteotomy (FDO) is the preferred treatment to correct excessive anteversion, however the condition may persist or recur postoperatively. Retrospective clinical and kinematic evaluation of 75 spastic diplegic CP patients was conducted for a mean duration of 22 months following proximal FDO. The patients were divided into two groups depending on the correction or persistence of IHR evident at kinematics after surgery. If corrected, mean patient follow-up was extended to 53 months. Outcomes were analyzed using Two Proportions Equality, Mann–Whitney and Wilcoxon tests. IHR persisted in 33.3% of cases at mean follow-up of 22 months and subtrochanteric femur osteotomy was more frequent in this group (p=0.033). Thirty-five of the fifty-four patients with first-round gait correction were monitored during the extended follow-up. Those for whom IHR recurred (9.5%) had undergone FDO at a comparatively younger age. Patient gender, operations prior to or at the time of femoral osteotomy, topographic classification, GMFCS level, or the extent of preoperative clinical and kinematic abnormalities had no apparent influence on persistence or recurrence of abnormal gait.

New Technique: A Novel Femoral Derotation Osteotomy for Malrotation following Intramedullary Nailing

A 19-year-old female patient sustained a closed spiral midshaft femoral fracture and subsequently underwent femoral intramedullary nail insertion. At followup she complained of difficulty in walking and was found to have a unilateral in-toeing gait. CT imaging revealed 30 degrees of internal rotation at the fracture site, which had healed. A circumferential osteotomy was performed distal to the united fracture site using a Gigli saw with the intramedullary femoral nail in situ. The static distal interlocking screws were removed and the malrotation was corrected. Two further static distal interlocking screws were inserted to secure the intramedullary nail in position. The osteotomy went on to union and her symptoms of pain, walking difficulty, and in-toeing resolved. Our paper is the first to describe a technique for derotation osteotomy following intramedullary malreduction that leaves the intramedullary nail in situ.

The Effects of Femoral Derotation Osteotomy in Cerebral Palsy: A Kinematic and Kinetic Study

We attempted to quantify the effects of isolated femoral derotation osteotomies using clinical evaluation and gait analysis (kinematics and kinetics) in patients with cerebral palsy (CP). Twelve children with CP were evaluated before and 10 months after isolated femoral derotation osteotomy, and 15 healthy children were evaluated as controls. There were significant improvements on clinical examination. A better position of the hip and ankle in the transverse plane was evident and significant changes occurred in terms of hip and ankle kinetics after surgery. Improvements in kinematics and hip and ankle power are very important biomechanically. The correction of lever arm dysfunction and more physiological hip and ankle power generation result in an improvement in terms of energy consumption, leading to a more functional and economic gait pattern.

Do we need femoral derotation osteotomy in DDH of early walking age group? A clinico-radiological correlation study

The occurrence of exaggerated femoral anteversion and the role of femoral derotation osteotomy in developmental dysplasia of hip, especially early walking age group are controversial. We evaluated femoral anteversion, acetabular anteversion, acetabular index in 15 dislocated hips and 11 normal hips in cases of unilateral dislocation of hip in DDH of age group 12-48 months. We correlated this femoral anteversion with the intra operative "test of stability" which is described by Zadeh et al. We found that there was no statistically significant difference in femoral anteversion between dislocated and normal hips. In all the 15 cases we did open reduction by anterior approach (Somerville approach) and evaluated the position for maximum stability. In 3 cases we were unable to perform test of stability as they needed femoral shortening for reduction of joint. In the rest 12 hips, 10 were stable in flexion and abduction while 2 were stable in flexion. None of the hips required internal rotation for stability. Hence we did salters osteotomy in all the hips and femoral shortening through lateral approach in 3 cases. At a minimum follow up of 18 months all the hips were clinically stable and none of them dislocated till final follow up. The mean correction of acetabular index was 15.4 degrees and the outcome was excellent in 8 hips and good in 7 hips as per modified McKay's criteria. Hence we recommend that femoral derotation osteotomy is not needed in DDH of early walking age group. As the surgical treatment of DDH involves complex osteotomies around the hip and these surgeries have effect on long term outcome, MRI evaluation of femoral anteversion as a part of pre operative evaluation is advised. Also, as the intra operative evaluation needs enough clinical experience and it can not be performed in cases requiring femoral shortening for reduction, we consider pre operative evaluation of femoral anteversion by MRI as essential rather than adjunctive.