Reliable angle assessment during periacetabular osteotomy with a novel device

Intraoperative Angle Measurement of Anatomical Structures: A Systematic Review

Ensuring precise angle measurement during surgical correction of orientation-related deformities is crucial for optimal postoperative outcomes, yet there is a lack of an ideal commercial solution. Current measurement sensors and instrumentation have limitations that make their use context-specific, demanding a methodical evaluation of the field. A systematic review was carried out in March 2023. Studies reporting technologies and validation methods for intraoperative angular measurement of anatomical structures were analyzed. A total of 32 studies were included, 17 focused on image-based technologies (6 fluoroscopy, 4 camera-based tracking, and 7 CT-based), while 15 explored non-image-based technologies (6 manual instruments and 9 inertial sensor-based instruments). Image-based technologies offer better accuracy and 3D capabilities but pose challenges like additional equipment, increased radiation exposure, time, and cost. Non-image-based technologies are cost-effective but may be influenced by the surgeon's perception and require careful calibration. Nevertheless, the choice of the proper technology should take into consideration the influence of the expected error in the surgery, surgery type, and radiation dose limit. This comprehensive review serves as a valuable guide for surgeons seeking precise angle measurements intraoperatively. It not only explores the performance and application of existing technologies but also aids in the future development of innovative solutions.

John Charnley Award: A Quantitative Fluoroscopic Tool Improves Acetabular Fragment Positioning in Periacetabular Osteotomy

BACKGROUND

Radiographic assessment of acetabular fragment positioning during periacetabular osteotomy (PAO) has been linked to hip survivorship. Intraoperative plain radiographs are time and resource intensive, while fluoroscopy can introduce image distortion affecting measurement accuracy. Our purpose was to determine whether intraoperative fluoroscopy-based measurements with a distortion correcting fluoroscopic tool improved PAO measurement targets.

METHODS

We retrospectively reviewed 570 PAOs; 136 PAOs utilized a distortion correcting fluoroscopic tool, and 434 PAOs performed with routine fluoroscopy, prior to this technology. Lateral center-edge angle (LCEA), acetabular index (AI), posterior wall sign (PWS), and anterior center-edge angle (ACEA) were measured on preoperative standing radiographs, intraoperative fluoroscopic images, and postoperative standing radiographs. Defined target zones of correction were AI: 0-10^°, ACEA: 25-40^°, LCEA: 25-40^°, PWS: negative. Postoperative correction in zones and patient-reported outcomes were compared using chi-square tests and paired t-tests, respectively.

RESULTS

The average difference between postcorrection fluoroscopic measurements and 6-week postoperative radiographs was 0.21° for LCEA, 0.01° for ACEA, and -0.07° for AI (all P < .01). The PWS agreement was 92%. The percentages of hips meeting target goals overall improved with the new fluoroscopic tool: 74%-92% for LCEA (P < .01), 72%-85% for ACEA (P < .01), and 69 versus 74% for AI (P = .25), though there was no improvement in PWS (85 versus 85%, P = .92). All patient-reported outcomes except PROMIS Mental Health were significantly improved at most recent follow-up.

CONCLUSIONS

Our study demonstrated improved PAO measurements and target goals with the use of a distortion correcting quantitative fluoroscopic real-time measuring device. This value-additive tool gives reliable quantitative measurements of correction without interfering with surgical workflow.

What is the agreement between intraoperative fluoroscopy and postoperative radiographs in Bernese periacetabular osteotomy?

BACKGROUND

It is important to reorient the acetabular fragment into an optimal position and version to ensure a good long-term outcome after Bernese periacetabular osteotomy (PAO). Unfortunately, the intraoperative balance between overcorrection and undercorrection remains challenging for the surgeon. The purpose of this study was to answer two questions: (1) Does the femoral head coverage measured on intraoperative fluoroscopy agree with that measured on postoperative radiography? (2) What is the reliability of intraoperative fluoroscopy in identifying hip center correction in PAO?

METHODS

A total of 173 patients (173 hips) who underwent PAO for developmental dysplasia of the hip (DDH) at our center from July 01, 2020, to December 31, 2020, were retrospectively reviewed. Imaging data from 111 patients (female/male, 98/13; right/left, 72/39; mean age, 28.93 years) were included in this study. The analysis included measurement of the lateral center-edge angle (LCEA), acetabular index (AI), anterior wall index (AWI), posterior wall index (PWI), extrusion index (EI), and medial offset distance (MO). These measurements were acquired from intraoperative fluoroscopic images and postoperative radiographs and compared by paired t test using SPSS (version 24.0). Significance was determined at a p value of < 0.05. Bland-Altman analysis, conducted using GraphPad Software (version 9), was used to quantify the agreement between intraoperative fluoroscopic images and postoperative radiographs.

RESULTS

The means (standard deviations, SDs) of the LCEA, AI, AWI, PWI, EI, and MO obtained on intraoperative fluoroscopy were 32.86° (5.73°), 0.66° (5.55), 0.29 (0.10), 0.75 (0.17), 11.15% (6.50%), and 8.49 mm (3.68 mm), respectively. On postoperative radiography, the corresponding values were 32.91° (6.31°), 1.63° (5.22°), 0.29 (0.15), 0.85 (0.14), 11.27% (7.36%), and 9.60 mm (3.79 mm). The differences in the LCEA, AWI, and EI acquired from intraoperative fluoroscopic images and postoperative radiographs were not significant (p = 0.90, 0.95, and 0.83, respectively), but those in the AI, PWI, and MO were significant (p < 0.05). The mean biases (95% limits of agreement) of the LCEA, AI, AWI, PWI, EI, and MO were - 0.04 (- 6.85), - 0.97 (- 7.78), 0 (- 0.30), - 0.11 (- 0.36), - 0.12 (- 11.92), and - 1.11 (- 5.51), respectively.

CONCLUSION

The LCEA, EI, and AWI can be used to reliably predict postoperative femoral head coverage at the level of 2D graphics. Acetabular inclination can be cautiously assessed using AI on intraoperative fluoroscopy. In the absence of intraoperative 3D image evaluation, the AWI and PWI demonstrate acceptable agreement between fluoroscopy and radiography in assessing the acetabular version. Although the MO shows slight bias, it can be helpful in properly positioning the acetabulum during PAO.

Three-dimensional acetabular orientation during periacetabular osteotomy: a video analysis of acetabular rim position using an external fixator as navigation tool during reorientation procedure

INTRODUCTION

Bernese periacetabular osteotomy is an effective procedure for treating acetabular dysplasia. However, limited visual control of the acetabular position during surgery may result in under- or overcorrection with residual dysplasia or femoroacetabular impingement. Thus, we wanted to find a simple method to control the effect of correction in the sagittal and coronal plane.

METHOD

The acetabular coordinates are shown by two perpendicular tubes of an external fixator mounted onto a third tube that is fixed to the acetabular fragment with two Schanz screws. This method enables the isolated acetabular reorientation in the coronal, sagittal, and transverse plane. In a sawbone pelvis model, the acetabular rim is marked with a copper wire and a silicon adherent. To show the radiographic effect on acetabular parameters and the rim position, we visualized correction in the coronal and sagittal plane under fluoroscopic control.

RESULTS

Lateral rotation of the acetabular fragment had the highest impact on radiographic lateral coverage of the femoral head. But also ventral coverage increased during isolated lateral rotation. Anterior rotation showed almost no effect on lateral coverage and just a little effect on ventral coverage but caused severe total acetabular retroversion.

CONCLUSION

Three-dimensional control of the acetabular orientation during periacetabular osteotomy is important to avoid over- and under-correction. Isolated lateral rotation of the acetabular fragment should be the predominant direction of correction during periacetabular osteotomy. Ambitious anterior correction may be the main source for severe acetabular retroversion following periacetabular osteotomy.

Computer assistance in hip preservation surgery-current status and introduction of our system

INTRODUCTION

Preservation surgery of the hip with open or arthroscopic approach has always been challenging as complex 3-D anatomy and limited surgical access make intraoperative evaluation difficult. Recent advances in computer technology offer a wide range of innovative solutions with a goal to improve accuracy and safety of corrective procedures on human joints.

METHOD

The author critically reviews currently available literature in the field of computer assistance in hip preservation surgery. Basic features of unique planning software and navigation surgical system used in treatment of femoroacetabular impingement and hip dysplasia are introduced.

RESULTS

Currently available software provides preoperative identification of hip deformity on CT-based 3-D model and planning of the surgical correction using kinematic protocols. Real-time intraoperative 3-D orientation is possible, and execution of surgical correction can be performed either with navigation of surgical tools or with printed templates. Computer assistance in hip preservation surgery is in the developing phase. First clinical experiences of its use in treatment of femoroacetabular impingement, hip dysplasia, hip tumors, and avascular necrosis of the femoral head are promising.

CONCLUSION

Computer assistance has been applied for treatment of several hip disorders. Technical advances are suggested and quality basic studies and clinical trials are encouraged for the novel technology to become more user friendly and widely accepted.

Preoperative incipient osteoarthritis predicts failure after periacetabular osteotomy: 69 hips operated through the anterior intrapelvic approach

BACKGROUND

Untreated developmental hip dysplasia may result in pain, loss of function and is a common cause of osteoarthritis (OA). The periacetabular osteotomy (PAO) was developed to relieve symptoms and postpone further degeneration of the hip. We aimed to assess preoperative clinical and radiographic prognostic factors and evaluate survivorship of PAO after medium-term follow-up of 7.4 (2-15) years.

METHODS

59 patients (69 hips) operated with a PAO through an anterior intrapelvic approach from 1999 to 2011 were retrospectively identified. The patients were evaluated radiographically and clinically with Harris Hip Score, Western Ontario and McMaster Universities Osteoarthritis Index and 15D quality of life questionnaires. Survival analyses identified native hip joint survival predictors.

RESULTS

9 hips (9 patients) were converted to a total hip arthroplasty (THA). Of the 50 remaining patients (60 hips), 44 patients (54 hips) were examined at medium-term follow-up. 3 patients were lost to follow-up or declined participation and 3 were interviewed by telephone. Patient age at time of surgery was 32 (14-44) years. Survival analyses showed 84.3% (95% confidence interval [CI], 68.7-92.5%) survival of the native hip at 8 years follow-up (number at risk 32) (worst case scenario 80% survival at 8 years, 95% CI, 63.9-89.2%, number at risk 32). Cox regression with presence of preoperative OA (Tönnis ⩾1), showed a crude hazard ratio for conversion to THA with preoperative OA of 13.73, p < 0.001.

CONCLUSIONS

Periacetabular osteotomy through the anterior intrapelvic approach can be performed safely and with satisfactory results at medium-term follow-up. The presence of preoperative incipient OA (Tönnis ⩾1) is the most important predictor for poor hip joint survival.

Are changes in pain associated with changes in quality of life and hip function 2 years after periacetabular osteotomy? A follow-up study of 321 patients

Symptomatic hip dysplasia is primarily treated surgically with periacetabular osteotomy (PAO). It is unclear whether changes in quality of life (QoL) and changes in hip function follow the same pattern of improvement as pain following PAO. The aim of the study is to investigate whether changes in pain were associated with changes in QoL and hip function 2 years after PAO. Furthermore, to examine patient satisfaction 2 years after PAO. This is a follow-up study with data from Aarhus University Hospital Denmark. Pain was measured using the Visual Analogue Scale, QoL with Short-Form 36 and hip function with Hip disability and Osteoarthritis Outcome Score both preoperatively and 2 years after PAO in 321 patients. Multiple linear regressions were applied. Significant mean improvements in pain, QoL and hip function were found (P < 0.05). Significant associations between changes in pain and changes in physically related QoL and changes in hip function, respectively were found (P < 0.05). A non-significant association between changes in pain and changes in mentally- related QoL was found (P = 0.13). The majority of patients (84%) reported satisfaction with the result of PAO and would undergo PAO again if they had known the results in advance. The study had a loss to follow-up of 26%. Decreased pain was significantly associated with increased physically related QoL and improved hip function 2 years after PAO. A non-significant association between decreased pain and increased mentally related QoL was found. Patients were in general satisfied with treatment and results 2 years after PAO.

Do Radiographic Parameters of Dysplasia Improve to Normal Ranges After Bernese Periacetabular Osteotomy?

BACKGROUND

The goal of periacetabular osteotomy (PAO) is to improve the insufficient coverage of the femoral head and achieve joint stability without creating secondary femoroacetabular impingement. However, the complex tridimensional morphology of the dysplastic acetabulum presents a challenge to restoration of normal radiographic parameters. Accurate acetabular correction is important to achieve long-term function and pain improvement. There are limited data about the proportion of patients who have normal radiographic parameters restored after PAO and the factors associated with under- and overcorrection.

QUESTIONS/PURPOSES

(1) What is the proportion of patients undergoing PAO in which the acetabular correction as assessed by the lateral center-edge angle (LCEA), anterior center-edge angle (ACEA), acetabular inclination (AI), and extrusion index (EI) is within defined target ranges? (2) What patient and preoperative factors are associated with undercorrection of the acetabulum as defined by a LCEA < 22°, a factor that has been reported to be associated with PAO failure at 10-year followup?

METHODS

Between January 2007 and December 2011 we performed 132 PAOs in 116 patients for treatment of symptomatic acetabular dysplasia. One patient with Legg-Calvé-Perthes disease, one with multiple osteochondromatosis, and two with concomitant femoral osteotomy were excluded. A total of 128 hips (112 patients) were included. The hip cohort was 76% (97 of 128) female and the mean age at surgery was 28.5 years (SD 8.7 years). Correction of LCEA between 25° and 40°, ACEA between 18° and 38°, Tönnis angle between 0° and 10°, and EI ≤ 20% were defined as adequate based on normative values. Values lower than the established parameters were considered undercorrection for the LCEA and ACEA and those higher than the established values were considered overcorrection. Because postoperative LCEA < 22^o has been previously associated with PAO failure at a minimum of 10-year followup, in this study we sought to measure whether demographic factors including age, gender, body mass index, and severity of acetabular dysplasia assessed by preoperative LCEA, ACEA, AI, and EI were associated with undercorrection. Postoperative radiographs were obtained at minimum of 1 month after surgery (mean, 7 months; range, 1-44 months) and were measured by a professional research assistant and a hip reconstruction fellow not involved in the clinical care of the patients. No patient was lost to followup.

RESULTS

Of the 128 hips, the proportion of hips with radiographic parameters within the established range was 78% (100 hips) for the LCEA, 86% (110 hips) for the ACEA, 89% (114 hips) for the AI, and 80% (102 hips) for the EI. For hips with an inadequate correction, the LCEA was more often undercorrected than overcorrected (20% versus 2%; 95% confidence interval [CI], 11%-27%; p < 0.001), whereas the ACEA was more often overcorrected than undercorrected (11% versus 3%; 95% CI, 1%-15%; p = 0.03) After adjusting for age, sex, body mass index, and preoperative radiographic parameters including ACEA, AI, and EI, we found that the preoperative LCEA was the only independent factor associated with a postoperative LCEA < 22° (odds ratio, 0.92; 95% CI, 0.87-0.97; p = 0.003), indicating that hips with lower preoperative LCEA were more likely to have a LCEA < 22°. For each additional degree of preoperative LCEA, the odds of LCEA < 22° were reduced by 15%.

CONCLUSIONS

Acetabular correction after PAO performed by two experienced surgeons was adequate for individual radiographic parameters in most but not all hips. Hips with more severe dysplasia preoperatively are at higher risk for undercorrection as assessed by the LCEA. This intuitive information may help surgeons performing PAO in severely dysplastic hips plan for possible combined procedures including a femoral osteotomy if PAO alone does not allow for adequate correction of femoral head coverage and a congruous concentric hip. Further studies are planned to determine whether the long-term hip function and pain in patients whose hips were corrected within these established parameters will be improved in comparison to those that were under- or overcorrected.

LEVEL OF EVIDENCE

Level III, therapeutic study.

No correlations between radiological angles and self-assessed quality of life in patients with hip dysplasia at 2-13 years of follow-up after periacetabular osteotomy

BACKGROUND

Only few studies have described patients' health-related quality of life (QoL) after periacetabular osteotomy (PAO). Thus, there is a lack of data on the self-assessed outcome of patients operated with PAO, and none of the existing studies correlate the results from Medical Outcomes Short Form-36 questionnaire (SF-36) with the radiological parameters.

PURPOSE

To investigate the health-related QoL for patients with hip dysplasia operated with PAO and to investigate whether QoL is associated with the acetabular angles or hypermobility.

MATERIAL AND METHODS

Out of 388 patients, 228 patients (mean age, 40.5 years; mean follow-up, 7.1 years) returned the SF-36 and Beighton questionnaires. The patient's QoL was compared to reference data from a Danish population. Center-edge (CE) and acetabular index (AI) angles were measured before and after PAO and the association with the patients' QoL was tested with logistic regression.

RESULTS

For both men and women the postoperative SF-36 score was significantly lower than for the reference data for a Danish population, especially for those dimensions concerning physical health. No association was found between the patients' CE or AI angles before or after PAO and their subsequent QoL. Significant associations were found between both Physical Component Score (PCS) and physical function (PF) and follow-up time after the operation. The adjusted OR for a PCS ≥ 50 was 0.87 (95% CI 0.76-0.99) and for a PF ≥ 85 0.81 (95% CI 0.71-0.91). No association between hyper mobility and PCS, PF, or bodily pain (BP) was found.

CONCLUSION

The physical components of QoL in patients undergoing PAO are significantly lower than the Danish population used as reference. Furthermore, the results suggest that physical function after PAO decreases with longer follow-up time. Neither the acetabular angles nor hypermobility is associated with the physical components of QoL.

Dilemmas in imaging for peri-acetabular osteotomy

Peri-acetabular osteotomy is an established surgical treatment for symptomatic acetabular dysplasia in young adults. An anteroposterior radiograph of the pelvis is commonly used to assess the extent of dysplasia as well as to assess post-operative correction. Radiological prognostic factors include the lateral centre-edge angle, acetabular index, extrusion index and the acetabular version. Standing causes a change in the pelvis tilt which can alter certain radiological measurements relative to the supine position. This article discusses the radiological indices used to assess dysplasia and reviews the effects of patient positioning on these indices with a focus on assessment for a peri-acetabular osteotomy. Intra-operatively, fluoroscopy is commonly used and the implications of using fluoroscopy as a modality to assess the various radiological indices along with the effects of using an anteroposterior or posteroanterior fluoroscopic view are examined. Each of these techniques gives rise to a slightly different image of the pelvis as the final image is sensitive to the position of the pelvis and the projection of the x-ray beam.

Cite this article: Bone Joint J 2014;96-B:1155–60.

What factors predict failure 4 to 12 years after periacetabular osteotomy?

BACKGROUND

The goal of periacetabular osteotomy (PAO) is to delay or prevent osteoarthritic development in dysplastic hips. However, it is unclear whether the surgical goals are achieved and if so in which patients. This information is essential to select appropriate patients for a durable PAO that achieves its goals.

QUESTIONS/PURPOSES

We therefore (1) determined hip survival rates; (2) determined how many preserved hips were functionally unsuccessful after PAO; and (3) identified demographic, clinical, and radiographic factors predicting failure after PAO.

METHODS

We retrospectively reviewed 316 patients (401 hips) who had PAO between December 1998 and May 2007. We evaluated radiographic parameters of dysplasia and osteoarthritis and obtained WOMAC scores. Through inquiry to the National Registry of Patients, we identified conversions to THA. Risk factors for conversion to THA were assessed. Minimum followup was 4 years (mean, 8 years; range, 4-12 years).

RESULTS

The overall Kaplan-Meier hip survival rate was 74.8% at 12.4 years. A WOMAC pain score of 10 or more, suggesting clinical failure, was observed in 13% of preserved hips at last followup. Higher age, preoperative Tönnis grade of 2, incongruent hip, postoperative joint space width of 3 mm or less, and postoperative center-edge angle of less than 30° or more than 40° predicted conversion to THA.

CONCLUSIONS

PAO preserved three of four hips with most functioning well at 4- to 12-year followup. When planning surgery, surgeons should attempt to achieve hip congruence and a center-edge angle of between 30° to 40° to improve the durability of PAO.

LEVEL OF EVIDENCE

Level II, prognostic study. See Instructions for Authors for a complete description of levels of evidence.