Femoral Derotation Osteotomy Technique for Excessive Femoral Anteversion

Derotational femoral osteotomy locations and their influence on joint reaction forces in dysplastic hips

Femoral version (FV) deformities are common in patients with developmental dysplasia of the hip (DDH) and may contribute to cartilage damage due to abnormal joint loading. Derotational femoral osteotomy (DFO) surgery corrects FV deformities. However there is little consensus about the femoral transection location for DFO, and its influence on joint loads is unknown. The purpose of this study was to compare the effects of two common DFO locations on muscle forces and hip joint reaction forces (JRFs) in patients with DDH. DFO was simulated in nine patients with DDH and abnormal FV using patient-specific musculoskeletal models. Femoral transection for DFO was separately simulated proximal and distal to the lesser trochanter and FV values were corrected to an idealized 15°. JRFs during early and late stance of gait were compared between the two simulated transection locations. Most changes to JRFs were similar between proximal and distal DFO, however, statistically significant differences were found for the medial JRF component during late stance among patients with femoral anteversion (p = 0.01). Force changes from five hip muscles were significantly different between DFO locations, however, changes were minimal. Most changes after DFO in patients with femoral retroversion were opposite of those with femoral anteversion, with anteroposterior and superior JRFs increasing after retroversion correction. After DFO correction, superior and medial JRFs in DDH patients remained elevated compared to controls. Understanding the influence of DFO location on muscle-generated hip forces can help surgeons justify decisions and potentially standardize surgical correction of FV deformities in patients with DDH.

Change of Femoral Anteversion Angle in Children With Intoeing Gait Measured by Three-Dimensional Computed Tomography Reconstruction: 3-Year Follow-Up Study

OBJECTIVE

To investigate long-term changes in femoral anteversion angle (FAA) in children with intoeing gait and to identify factors that affect FAA changes.

METHODS

We retrospectively analyzed three-dimensional computed tomography data from 2006 to 2022 of children with intoeing gait with ≥3 years of follow-up without active treatment. The study examined the mean changes in FAA, the effects of sex, age, and initial FAA on FAA change, and mean FAAs by age. Changes in FAA severity up to eight years of age were also observed and analyzed by sex.

RESULTS

A total of 126 lower limbs of 63 children (30 males, 33 females) with intoeing gait were included, with a mean age of 5.11±1.05 years and a mean follow-up period of 43.59±7.74 months. The initial FAA was 41.42°±8.29° and the follow-up FAA was 33.25°±9.19°, indicating a significant decrease (p<0.001). Significant correlations were observed between age and changes in FAA, as well as between initial FAA and changes in FAA (r=0.248, p=0.005; r=-0.333, p<0.001). At age 8 years, only 22 limbs were classified as having mild FAA severity.

CONCLUSION

During the follow-up period, children with intoeing gait had a significant decreased in FAA. No significant difference in FAA change was found between sex, but younger children and those with greater initial FAA were more likely to have decreased FAA. However, most children retained moderate to severe severity of increased FAA. Further studies are required to validate these findings.

Percutaneous Femoral Derotational Osteotomy in the Skeletally Immature Patient

Percutaneous femoral derotational osteotomies are performed in both adult and pediatric patients for excessive symptomatic femoral anteversion or retroversion^1,2. The aim of the procedure is to correct version abnormalities with use of a minimally invasive technique³.

Description

This is a percutaneous procedure that involves creation of femoral drill holes at the osteotomy site prior to reaming the canal⁴. External fixator pins are placed proximal and distal to the osteotomy site prior to completing the osteotomy. These pins are derotational markers for the surgeon and act to hold the correction with use of an external fixator while the interlocking screws are being placed. The pins are placed at a degree of divergence that is equal to the degree of intended derotation so that the pins will become parallel in the axial plane following derotation of the femur. The percutaneous osteotomy is then completed with use of an osteotome, and the trochanteric entry nail is passed across the osteotomy site while correcting rotation. Once rotation is fully corrected and the pins are parallel, the external fixator is placed to hold the rotation and interlocking screws are placed.

Alternatives

Nonoperative alternatives to this procedure include physical therapy for gait training and strengthening as well as modalities to address hip and knee pain that may be associated with version abnormalities. Although physical therapy is often prescribed, it must be noted that excess version is a fixed osseous structural pathology that therapy cannot address. Additionally, compensatory mechanisms that may be taught to improve gait and walk with a neutral foot progression angle may exacerbate hip or knee pathology as a result of the underlying version abnormality. Surgical alternatives include derotational osteotomies of the proximal or distal aspects of the femur with use of an open technique with plate fixation, as opposed to an intramedullary nail following percutaneous diaphyseal osteotomy as presented here¹. Additionally, an open technique with intramedullary nail fixation may be performed⁵.

Rationale

Excessive anteversion can cause both hip and knee symptoms, including hip pain, instability, labral and psoas pathology, and patellofemoral instability⁶. Excessive retroversion can cause impingement between the femoral neck and acetabulum, which results in pathology of the labrum and articular cartilage⁷. Additionally, abnormalities of version often lead to gait disturbances with frequent tripping and difficulty running⁸. Children with femoral version abnormalities have limited remodeling potential after age 8³. A derotational osteotomy may be performed to correct symptomatic excess femoral version in an older child or adolescent.

Expected Outcomes

The patient may be weight-bearing as tolerated with upper-extremity assistance immediately following the procedure. The osteotomy typically heals between 6 and 12 weeks, and the patient may return to activities as tolerated once the osteotomy is healed. Gordon et al. described the outcomes of a similar technique for femoral derotational osteotomy in skeletally immature patients with excessive femoral anteversion³. The study retrospectively reviewed the results of the technique in 13 patients and 21 limbs at a minimum follow-up of 1 year. All patients complained of tripping and gait abnormalities preoperatively. All patients noted gait improvement, and no intraoperative or postoperative complications were reported. Healing of the osteotomy occurred at a mean of 6 weeks postoperatively. No patient developed osteonecrosis. We routinely remove hardware in skeletally immature patients approximately 1 year postoperatively. Complications are rare and include hardware irritation, infection, nonunion, and neurovascular injury.

Important Tips

Preoperative planning is critical for this procedure, and the surgeon should know the intended degree of derotation, the location of the osteotomy relative to the greater trochanter, the length of the nail, and the approximate diameter of the nail prior to entering the operating room.Percutaneous bicortical femoral drill holes are created at the site of the osteotomy prior to reaming to allow for egress of reamings and bone marrow elements at the osteotomy site, which serve as autograft and stimulate bone healing. Additionally, the drill holes provide ventilation to prevent excessive intramedullary pressure during reaming^9-11.External fixator pins are placed proximal and distal to the osteotomy prior to completion of the osteotomy to allow for rotational assessment after completion of the osteotomy. Placing these pins bicortically so that they are secure in the bone and ensuring that the divergence is correct for the intended amount of derotation is critical in this procedure because once the osteotomy is complete, the pins are the only markers of rotation the surgeon has to guide the correction.An external fixator is helpful in holding the femur at the intended degree of derotation during placement of the interlocking screws.

Acronyms & Abbreviations

ROM = range of motionCT = computed tomographyMRI = magnetic resonance imagingAP = anteroposteriorGT = greater trochanterAV = anteversionER = external rotationIR = internal rotationA = anteriorP = posteriorM = medialL = lateralXR = X-rayProx = proximalEx fix = external fixatorWBAT = weight-bearing as toleratedBLE = bilateral lower extremitiesDVT = deep venous thrombosisPT = physical therapyppx = prophylaxisAVN = avascular necrosis (osteonecrosis).

Assessment of Femoral Torsion on Magnetic Resonance Imaging is More Reliable Using Axial-Oblique Sequences Compared With Standard Axial Slices in Patients With Femoroacetabular Impingement Syndrome

PURPOSE

To determine the agreeability of femoral torsion measurements on axial and oblique axial magnetic resonance imaging (MRI) sequences in patients with femoroacetabular impingement syndrome (FAIS).

METHODS

Patients who underwent primary hip arthroscopy for FAIS between January 2012 to January 2019 were identified. Inclusion criteria were all patients with an MRI scan containing the pelvis and knee imaging. MRI-based measurements of femoral torsion were performed on axial and oblique-axial slices by 2 raters, and inter-rater and intrarater reliability was assessed. Bland Altman plots were constructed to evaluate the agreeability between femoral torsion measurements performed using axial and oblique-axial slices. Bivariate correlation analyses were performed to assess the relationship between measurement methods on each respective scan. A linear regression was performed between measurements performed using axial and oblique-axial sequences.

RESULTS

A total of 164 patients were included. The mean true-axial and oblique axial femoral torsion were 12.2° ± 9.9° and 11.1° ± 9.2°, respectively. The intrarater reliability for axial and oblique-axial measurements were 0.993 and 0.997, respectively. The inter-rater reliability for axial and oblique-axial measurements were 0.925 and 0.965, respectively. The number of differences within the limits of agreement for axial and oblique-axial femoral torsion measurements was 58.54%. On Pearson correlation analysis, strong positive correlations were found between oblique-axial measurements at multiple time points (r = 0.994, P < .001), as well as axial measurements at multiple time points (r = 0.986, P < .001). A strong positive correlation was found between axial and oblique-axial measurements (r = 0.894, P < .001). A significant regression equation indicated that for each additional increase in axial femoral torsion, the oblique-axial femoral torsion increased 0.837 (95% confidence interval 0.772-0.901).

CONCLUSIONS

Femoral torsion values measured on oblique-axial sequences are smaller than on true-axial sequences. Femoral torsion measurements on axial and oblique-axial MRI sequences exhibit poor agreement. Oblique-axial sequences demonstrated greater measurement consistency at multiple timepoints. When evaluating torsional measurements, it is important to delineate which axial sequence was used, especially in patients with suspected severe femoral antetorsion. Standardization of MRI femoral version protocols within one's practice can ensure more consistent decision-making, especially in patients with suspected femoral antetorsion.

LEVEL OF EVIDENCE

Retrospective cohort, level III.

Femoral version deformities alter joint reaction forces in dysplastic hips during gait

Developmental dysplasia of the hip (DDH) causes hip instability and early-onset osteoarthritis. The focus on pathomechanics in DDH has centered on the shallow acetabulum, however there is growing awareness of the role of femoral deformities in joint damage. The objective of this study was to determine the influence of femoral version (FV) on the muscle and joint reaction forces (JRFs) of dysplastic hips during gait. Magnetic resonance images, in-vivo gait data, and musculoskeletal models were used to calculate JRFs and simulate changes due to varying FV deformities. Rotation about the long axis of the femur was added in the musculoskeletal models to simulate FV values from -5° (relative retroversion) to + 35° (increased anteversion). In our simulations, FV deformities caused the largest changes to the anteroposterior and resultant JRFs. From a normal FV of 15°, a 15° increase in femoral anteversion caused JRFs to be less posterior in early stance (Δ = 0.43 ± 0.22 xbodyweight) and more anterior in late stance (Δ = 0.60 ± 14 xbodyweight). Relative retroversion caused anteroposterior changes that were similar to anteversion in early stance but opposite in late stance. Resultant JRFs experienced the largest changes during late stance where anteversion raised the peak by 0.48 ± 0.15 xbodyweight and relative retroversion lowered the peak by 0.32 ± 0.30 xbodyweight. Increasing anteversion increased hip flexor and abductor muscle forces, which caused the changes in JRFs. Identifying how FV deformities influence hip joint loading can elucidate their role in the mechanisms of hip degeneration in patients with DDH.

Short-term Outcomes of Concomitant Femoral Derotation Osteotomy and Hip Arthroscopy

The goal of this study is to report the short-term outcomes of concomitant hip arthroscopy and femoral derotational osteotomy (FRO) to treat femoral malrotation and intra-articular pathology. Data were retrospectively reviewed for patients undergoing concomitant hip arthroscopy and FRO between March 2013 and January 2017. Patients were included if they had a minimum of 1 year of follow-up for modified Harris Hip Score (mHHS), Nonarthritic Hip Score (NAHS), Hip Outcome Score-Sports Specific Subscale (HOS-SSS), International Hip Outcome Tool (iHOT-12) score, 12-item Short Form Health Survey Physical component and Mental component (SF-12 P and SF-12 M, respectively) scores, Veterans RAND 12-item Health Survey Physical and Mental (VR-12 P and VR-12 M, respectively) scores, visual analog scale (VAS) score for pain, and patient satisfaction ratings. Rates for meeting the patient acceptable symptomatic state (PASS) and minimal clinically important difference (MCID) were also recorded. Nine hips were included, and mean follow-up was 36.9 months. Mean preoperative femoral version was 33.0°. Patients underwent 1 or more concomitant procedures, such as labral treatment, capsular plication, acetabuloplasty, or femoroplasty. At latest follow-up, significant improvement was seen for mHHS, NAHS, HOS-SSS, and VAS score. Additionally, rates of meeting the PASS for mHHS, iHOT-12 score, and HOS-SSS were 100%, 88.9%, and 55.6%, respectively. Rates of achieving MCID for mHHS and HOS-SSS were 77.8% and 66.7%, respectively. One hip required revision derotational osteotomy to treat overcorrection, and 3 hips underwent secondary surgery for hardware removal. Concomitant hip arthroscopy and FRO may yield improved outcomes for patients with concurrent intra-articular pathology and excessive femoral anteversion. Considering that no major complications were diagnosed, this procedure is also relatively safe. [Orthopedics. 2021;44(6):e739-e746.].

Clinically Significant Outcome Improvement After Hip Arthroscopy in Patients With Femoroacetabular Impingement Syndrome and Severe Femoral Torsion

Background:

The influence of femoral torsion on clinically significant outcome improvement after hip arthroscopy for femoroacetabular impingement syndrome (FAIS) has not been well-studied.

Purpose:

To quantify femoral torsion in FAIS patients using magnetic resonance imaging (MRI) and explore the relationship between femoral torsion and clinically significant outcome improvement after hip arthroscopy.

Study Design:

Cohort study; Level of evidence, 3.

Methods:

Included were patients who underwent hip arthroscopy for FAIS between January 2012 and August 2018 and had 2-year follow-up and preoperative MRI scans containing transcondylar slices of the knee. Participants were categorized as having severe retrotorsion (SR; <0°), normal torsion (NT; 0°-25°), and severe antetorsion (SA; >25°) as measured on MRI. Patient-reported outcomes (PROs) included the Hip Outcome Score–Activities of Daily Living, Hip Outcome Score–Sports Subscale, modified Harris Hip Score, 12-item International Hip Outcome Tool (iHOT-12), and visual analog scale (VAS) for pain and satisfaction. Achievement of Patient Acceptable Symptom State (PASS) and substantial clinical benefit (SCB) were analyzed among cohorts.

Results:

Included were 183 patients (SR, n = 13; NT, n = 154; SA, n = 16) with a mean age, body mass index, and femoral torsion of 30.6 ± 12.1 years, 24.0 ± 4.4 kg/m², and 12.55° ± 9.58°, respectively. The mean torsion was –4.5° ± 2.6° for the SR, 12.1° ± 6.8° for the NT, and 31.0° ± 3.6° for the SA group. There were between-group differences in the proportion of patients who achieved PASS and SCB on the iHOT-12, pain VAS, and any PRO (P < .05). Post hoc analysis indicated that the SA group achieved lower rates of PASS and SCB on the iHOT-12 and pain VAS, and lower rates of PASS on any PRO versus the SR group (P < .05); the SR group achieved higher rates of PASS and SCB on pain VAS scores versus the NT group (P = .003).

Conclusion:

The orientation and severity of femoral torsion during hip arthroscopy influenced the propensity for clinically significant outcome improvement. Specifically, patients with femoral retrotorsion and femoral antetorsion had higher and lower rates of clinically significant outcome improvement, respectively.

Reflections on Rotational Osteotomies around the Patellofemoral Joint

Torsional abnormalities of the femur represent a significant risk factor for patellar instability or patellofemoral complaints. Although their clinical implication has been demonstrated, there is still a debate going on about different aspects. These include, especially, the various methods of measurements with a wide range of physiologic values, the indication or clear recommendation for surgical correction, and the site of the rotational osteotomy. Nevertheless, good subjective and objective functional results were reported after femoral rotational osteotomies. This is mostly not a review of the literature, but a collection of personal thoughts and observations.

Differences in Femoral Torsion Among Various Measurement Methods Increase in Hips With Excessive Femoral Torsion

BACKGROUND

Correct quantification of femoral torsion is crucial to diagnose torsional deformities, make an indication for surgical treatment, or plan the amount of correction. However, no clear evaluation of different femoral torsion measurement methods for hips with excessive torsion has been performed to date.

QUESTIONS/PURPOSES

(1) How does CT-based measurement of femoral torsion differ among five commonly used measurement methods? (2) Do differences in femoral torsion among measurement methods increase in hips with excessive femoral torsion? (3) What is the reliability and reproducibility of each of the five torsion measurement methods?

METHODS

Between March and August 2016, we saw 86 new patients (95 hips) with hip pain and physical findings suggestive for femoroacetabular impingement at our outpatient tertiary clinic. Of those, 56 patients (62 hips) had a pelvic CT scan including the distal femur for measurement of femoral torsion. We excluded seven patients (seven hips) with previous hip surgery, two patients (two hips) with sequelae of Legg-Calvé-Perthes disease, and one patient (one hip) with a posttraumatic deformity. This resulted in 46 patients (52 hips) in the final study group with a mean age of 28 ± 9 years (range, 17-51 years) and 27 female patients (59%). Torsion was compared among five commonly used assessment measures, those of Lee et al., Reikerås et al., Jarrett et al., Tomczak et al., and Murphy et al. They differed regarding the level of the anatomic landmark for the proximal femoral neck axis; the method of Lee had the most proximal definition followed by the methods of Reikerås, Jarrett, and Tomczak at the base of the femoral neck and the method of Murphy with the most distal definition at the level of the lesser trochanter. The definition of the femoral head center and of the distal reference was consistent for all five measurement methods. We used the method described by Murphy et al. as our baseline measurement method for femoral torsion because it reportedly most closely reflects true anatomic femoral torsion. With this method we found a mean femoral torsion of 28 ± 13°. Mean values of femoral torsion were compared among the five methods using multivariate analysis of variance. All differences between two of the measurement methods were plotted over the entire range of femoral torsion to evaluate a possible increase in hips with excessive femoral torsion. All measurements were performed by two blinded orthopaedic residents (FS, TDL) at two different occasions to measure intraobserver reproducibility and interobserver reliability using intraclass correlation coefficients (ICCs).

RESULTS

We found increasing values for femoral torsion using measurement methods with a more distal definition of the proximal femoral neck axis: Lee et al. (most proximal definition: 11° ± 11°), Reikerås et al. (15° ± 11°), Jarrett et al. (19° ± 11°), Tomczak et al. (25° ± 12°), and Murphy et al. (most distal definition: 28° ± 13°). The most pronounced difference was found for the comparison between the methods of Lee et al. and Murphy et al. with a mean difference of 17° ± 5° (95% confidence interval, 16°-19°; p < 0.001). For six of 10 possible pairwise comparisons, the difference between two methods increased with increasing femoral torsion and decreased with decreasing femoral torsion. We observed a fair-to-strong linear correlation (R range, 0.306-0.622; all p values < 0.05) for any method compared with the Murphy method and for the Reikerås and Jarrett methods when compared with the Tomczak method. For example, a hip with 10° of femoral antetorsion according Murphy had a torsion of 1° according to Reikerås, which corresponds to a difference of 9°. This difference increased to 20° in hips with excessive torsion; for example, a hip with 60° of torsion according to Murphy had 40° of torsion according to Reikerås. All five methods for measuring femoral torsion showed excellent agreement for both intraobserver reproducibility (ICC, 0.905-0.973) and interobserver reliability (ICC, 0.938-0.969).

CONCLUSIONS

Because the quantification of femoral torsion in hips with excessive femoral torsion differs considerably among measurement methods, it is crucial to state the applied methods when reporting femoral torsion and to be consistent regarding the used measurement method. These differences have to be considered for surgical decision-making and planning the degree of correction. Neglecting the differences among measurement methods to quantify femoral torsion can potentially lead to misdiagnosis and surgical planning errors.

LEVEL OF EVIDENCE

Level IV, diagnostic study.