Screw fixation after tripe pelvic osteotomy is reliable: changes of acetabular correction are rare and do not correlate with risk factors.

PURPOSE: The aim of this examination was to assess whether there is a change of acetabular correction after triple pelvic osteotomy (TPO) and if so, whether there is a correlation with patient-specific risk factors or with certain periods in the postoperative course. METHODS: A consecutive series of 241 TPO was reviewed retrospectively. The close-meshed radiographic follow-up of the first 12 weeks comprised pelvic radiographs performed immediately after the procedure, 5 days, 6 and 12 weeks after TPO. Three observers measured the lateral center edge angle, acetabular index and the craniocaudal offset of the pubic osteotomy. Patient-specific risk factors (e. g. age, gender, body mass index, nicotine abuse) and certain periods in the postoperative course were correlated with a change of acetabular correction. RESULTS: After application of the exclusion criteria, 225 hips were available for further examination. Intraclass correlation coefficient resulted in predominantly excellent agreement between the measurements of the three observers (0.74-0.91). In 27 cases (12%), the three observers agreed on a change of acetabular correction. In 18 cases (8%), there was a slight change, in 9 cases (4%), a relevant change. The latter entailed consequences in the postoperative aftercare. General equation estimation did not show any correlation between a change of acetabular correction and patient-specific risk factors or certain periods in the postoperative course (p = 0.79-0.99). CONCLUSION: Every once treated hip should be followed-up with the same attention, irrespective of the apparent risk profile. There is no rationale to skip a radiographic follow-up in the first 12 weeks after TPO.

Age and magnitude of acetabular correction impair bone healing after triple pelvic osteotomy.

INTRODUCTION: The aim of this examination was to assess, which risk factors impair bone healing after triple pelvic osteotomy (TPO) in the treatment of symptomatic hip dysplasia. METHODS: A consecutive series of 241 TPO was reviewed retrospectively. Of these, a set of five postoperative radiographs was available, performed in a standardized regimen in the first year after surgery. Two experienced observers had to agree on the existence of a non-union on the radiographs obtained 1 year after TPO. Both observers measured the lateral center edge angle (LCEA) and acetabular index (AI) on all radiographs. Besides patient-specific risk factors, the magnitudes of acetabular correction and the amounts of a detectable slight change in acetabular correction were assessed. Binary logistic regression analysis and chi-squared test were used to detect the impact of the risk factor on bone healing. RESULTS: A total of 222 cases were left for further examination. In 19 of these, at least one osteotomy was not healed completely one year after surgery. Binary logistic regression showed a significant relationship between the risk factors "age" (p < 0.001; odds ratio (OR) 1.109 (95% CI 1.05-1.18)) as well as "magnitude of acetabular correction (LCEA)" (p = 0.01; OR 1.087 (95% CI 1.02-1.16)) and non-union. Pearson's chi-square test showed a relationship between the risk factor "wound healing disorder" and non-union (p < 0.001). LCEA and AI showed a slight increase from the first to the last follow-up (observer 1: 1.6° and 1.3°, resp.), but regression analysis for the risk factor "amount of postoperative change of acetabular correction (LCEA, AI)" did not show statistically significant values. CONCLUSION: The age at surgery and the magnitude of acetabular correction negatively influenced the healing progress of the osteotomy sites. The amount of a slight postoperative change of LCEA and AI did not correlate with a non-union.

Treatment of borderline hip dysplasia with triple pelvic osteotomy: preoperative values of acetabular index and lateral center edge angle can indicate overcorrection.

INTRODUCTION: After pelvic osteotomy for the treatment of symptomatic hip dysplasia, the longevity of the hip joint can be compromised by acetabular overcorrection. This iatrogenic pincer-type deformity is considered to be one of the major risk factors for persistent pain and progressing osteoarthritis. There is evidence that acetabula in the borderline range, defined by a lateral center edge angle (LCEA) between 18° and 25°, are more delicate to be orientated physiologically. The aim of this study was to assess the quality of acetabular orientation by triple pelvic osteotomy (TPO), established by Tönnis and Kalchschmidt, especially with respect to acetabular overcorrection. MATERIALS AND METHODS: A retrospective examination on 368 consecutive hips treated with TPOs was conducted. On the preoperative pelvic radiograph and the radiographic control 5 days after surgery, LCEA, acetabular index (AI), and anterior (AWI) and posterior wall index (PWI) were measured. According to the above-mentioned definition, the hips were divided into a borderline (n = 196) and a dysplastic (n = 172) group. Acetabular overcorrection was defined as when LCEA exceeded 35°, AI was below 0° and AWI exceeded 0.60, postoperatively. The postoperative occurrence of a relevant femoroacetabular impingement was correlated to these thresholds. Statistics comprised a priori power analysis, correlation analyses and receiver operating characteristics (ROC). RESULTS: In the borderline group, in 64 hips (32.7%), LCEA and AI indicated lateral overcorrection. In the dysplastic group, in 14 hips (8.1%), solely AI indicated overcorrection. In none of the hips, relevant anterior overcorrection was detected since AWI never exceeded 0.60. Chi-square test demonstrated a significant correlation between the occurrence of a postoperative femoroacetabular impingement and LCEA exceeding 35°, as well as AI below 0° (p < 0.001, resp.). Bravais-Pearson's analysis showed a significant correlation between the pre- and postoperative values of all parameters in the borderline and the dysplasia group (p < 0.001). Thus, ROC analysis could be performed and provided preoperative cutoff values for LCEA (23°) and AI (12.5°), hinting at postoperative overcorrection. CONCLUSION: The comparison of radiographic parameters after TPO showed a considerably greater percentage of laterally overcorrected acetabula in the borderline hips than in the dysplastic hips. According to the wall indices, anterior overcorrection was not observed. ROC analysis anticipated unfavorable lateral overcorrection when preoperative LCEA was above 23° and AI below 12.5°. These findings should sensitize the surgeon to the delicate acetabular correction in borderline dysplastic hips.

Association between posterior tibial slope and anatomic spinopelvic parameters: a retrospective cross-sectional study.

PURPOSE: Only a few publications considered the influence of the spinopelvic parameters on below-hip anatomy. There is a lack of evidence about the relationship between the anatomic spinopelvic parameters and the posterior tibial slope (PTS). Therefore, the aim of this study was to analyze the association between fixed anatomic spinopelvic parameters and PTS. METHODS: Adult patients presenting with lumbar, thoracic, or cervical complaints together with knee pain at a single hospital between 2017 to 2022 with available standing full-spine lateral radiograph and lateral knee radiograph were retrospectively reviewed. The measured parameters included the pelvic incidence (PI), the sacral kyphosis (SK), the pelvisacral angle, the sacral anatomic orientation (SAO), the sacral table angle, the sacropelvic angle and the PTS. Pearson's correlations and linear regression analyses were conducted. RESULTS: A total of 80 patients (44 women), median age 63 years were analyzed. A strong positive correlation was identified between PI and PTS (r = 0.70, p < 0.001). A strong negative correlation was observed between PI and SAO (r = - 0.74, p < 0.001). A strong positive correlation was observed between PI and SK (r = 0.81, p < 0.001). A univariable linear regression analysis showed that PTS can be deduced from PI according to the following formula: PTS = 0.174 × PI - 1.138. CONCLUSION: This study is the first to support a positive correlation between the PI and the PTS. We demonstrate that knee anatomy is individually correlated to pelvic shape and therefore influences spinal posture.

Acetabular deficiency in borderline hip dysplasia is underestimated by lateral center edge angle alone.

INTRODUCTION: In hip preservation surgery, the term "borderline hip dysplasia" was used when the lateral center edge angle (LCEA), historically described by Wiberg, measured 18-25°. In recent years, several radiographic parameters have been described to assess the antero posterior coverage of the femoral head, for example, the anterior and posterior wall index (AWI and PWI). This allowed an increasingly comprehensive understanding of acetabular morphology and a questioning of the borderline definition. MATERIAL AND METHODS: A retrospective review of 397 consecutive hips was performed, all treated with triple pelvic osteotomy (TPO) due to symptomatic hip dysplasia. On all preoperative pelvic radiographs with a LCEA of 18-25°, acetabular index (AI), AWI and PWI were measured. With these values, the hips were categorized into laterally, antero-laterally and postero-laterally dysplastic and stratified by gender. Intra- and interobserver correlation of the parameters was analyzed by intraclass correlation coefficient (ICC). RESULTS: According to LCEA, 192 hips were identified as "borderline dysplastic". Based on AWI and PWI, the categorization resulted in 116 laterally dysplastic (60.4%), 33 antero-laterally (17.2%) and 43 postero-laterally dysplastic hips (22.4%). Gender stratification revealed that male acetabula seemed to be slightly more postero-laterally deficient than female (mean PWI 0.80 vs 0.89; p = 0.017). ICC confirmed highly accurate and reproducible readings of all parameters. CONCLUSION: The rather high proportion of symptomatic hips labelled borderline dysplastic suggested, that there might be substantial acetabular deficiency not recognizable by LCEA. Comprehensive deformity analysis using LCEA, AI, AWI and PWI showed, that 40% of these hips were deficient either antero-laterally or postero-laterally. Male acetabula were more deficient postero-laterally than female.

Acetabular orientation in triple pelvic osteotomy: is intraoperative fluoroscopy reliable?

PURPOSE: In pelvic osteotomies, unfavorable balancing of the anterior and posterior acetabular wall can affect the longevity of the natural joint. This raises the question, whether intraoperative fluoroscopy is sufficiently accurate. The objective was to assess the correlation between acetabular parameters [lateral center edge angle (LCEA), acetabular index (AI), anterior wall index (AWI), posterior wall index (PWI)] acquired on intraoperative fluoroscopic images and postoperative pelvic radiographs and to analyze intra- and interobserver reliability of these parameters. METHODS: A retrospective examination was conducted on 206 consecutive cases (176 patients) after triple pelvic osteotomy (TPO). Every patient received a pre- and postoperative pelvic radiograph in supine position in exactly the same technique. A highly standardized surgical sequence allowed consistent intraoperative fluoroscopic imaging. LCAE, AI, PWI and AWI were measured by an experienced orthopedic surgeon and an orthopedic surgeon in training. Statistics comprised a priori power analysis, Bland-Altman analysis and intraclass correlation coefficient (ICC). RESULTS: A total of 165 cases were included. ICC between the parameters of the fluoroscopic images and postoperative radiographs was for LCEA: 0.935, AI: 0.936, AWI: 0.725 and PWI: 0.878. Intraobserver ICC for all parameters ranged from 0.953 to 0.989, interobserver ICC from 0.798 to 0.968, respectively. CONCLUSION: In the surgical treatment of hip dysplasia by means of TPO, intraoperative fluoroscopic imaging has proven to be reliable and accurate. Intraobserver correlation was excellent for all parameters. The correlation between the intraoperative fluoroscopic images and postoperative radiographs ranged from good to excellent, with the lowest values for the acetabular wall indices (AWI and PWI).

Proximal to distal phalangeal articular angle of the first proximal phalanx: Reliability and correlation with round sign.

BACKGROUND: To reduce the rate of correction loss in hallux valgus surgery, a proximal to distal phalangeal articular angle (PDPAA) of the proximal phalanx of the greater toe of> 8° is considered an indication for a combined Akin and Chevron osteotomy. The PDPAA is measured between the articular surfaces of the proximal phalanx of the greater toe. Viewed from a sagittal perspective, the joint surfaces are not perpendicular aligned to the phalanx axis. Therefore, the PDPAA might be confounded by pronation. This study aims to, first, evaluate the intra- and interobserver reliability of the PDPAA and, second, to analyze the correlation to first ray pronation. METHODS: In a consecutive series of 59 feet who underwent hallux valgus (HV) surgery, PDPAA, round sign and other angles were measured on weight-bearing radiographs pre- and postoperatively. After power analysis, the intraclass correlation coefficient (ICC) was used to calculate the intra- and interobserver reliability. The correlation of PDPAA with the round sign as well as angles defining the HV and the Hallux valgus interphalangeus (HVI) were evaluated. RESULTS: The PDPAA showed an excellent intra- and interobserver reliability (ICC 0.92 and 0.89, p < 0.05). The round sign did not correlate significantly with the PDPAA (p = 0.51). However, the PDPAA showed a moderate correlation with the interphalangeal angle (r = 0.51, p < 0.05) and fair inversely with the intermetatarsal angle (r = -0.45, p < 0.05). CONCLUSION: First, measurement of PDPAA is reliable. Second, PDPAA is not associated with first ray pronation, but a false low PDPAA is geometrically possible. A high PDPAA correlates with a relevant HVI and inversely correlates with the HV like the HVI. Hence, first ray pronation should be treated first and a remaining PDPAA of> 8° after intraoperatively reevaluation separately.

Residual dysplasia of the hip after successful ultrasound-monitored treatment: how does an infant's hip evolve?

Despite that normal values for the hip joint are reached at the end of ultrasound-monitored-treatment, the development of the acetabulum can be compromised during the growth phase. The acetabular index (AI) measured on a pelvic radiograph has been proven to be a reliable parameter. The aim of this study is to gain a better understanding of the dynamics of once-treated, residually dysplastic hips. This should be achieved by radiographically following these hips up to a milestone-examination at the end of preschool age. A total of 120 hips of consecutive 60 infants were included in this examination, each presenting with a residual developmental dysplasia of the hips (DDH) after successful ultrasound-monitored harness treatment. Radiographic follow-up was assessed retrospectively around 18 months, 3 years and 6 years of age, and the AI was measured. The age-dependent Tönnis classification was applied. The hips were assigned normal, mildly or severely dysplastic. Dependent t -test for paired samples indicated a highly significant improvement of the AI-values, including from the first to the second and from the second to the third follow-up. The percentage distribution into the Tönnis classification changed remarkably: in the first follow-up, 36 of the 120 hips were evaluated 'severely dysplastic', in the third follow-up only 1. On the other hand, three hips underwent acetabuloplasty. Even after normal values have been achieved at the end of ultrasound-monitored treatment, there remains a risk of residual dysplasia of the hips. Particularly, when the first radiographic examination shows nonphysiological findings, further close-meshed follow-up is recommended. Level of evidence: retrospective study of therapeutic outcome, consecutive patients, level II.

The epicondylar ratio can be reliably determined in both computed tomography and X-ray.

PURPOSE: One of the key factors to the successful revision of total knee arthroplasty (rTKA) is the reconstruction of the joint line, which can be determined using the epicondylar ratio (ER). The measurement is established in X-ray and MRI. However, it is not known whether computed tomography (CT) allows a more reliable determination. The objective was to assess the reliability of the ER in CT and to determine the correlation between the ER in CT and a.p. X-ray of the knee. METHODS: The ER was determined on X-ray and CT images of a consecutive series of 107 patients, who underwent rTKA. Measurements were made by two blinded observes, one measured twice. The inter- and intraobserver agreement, as well as the correlation between the two methods, were quantified with the Intraclass Correlation Coefficient. RESULTS: The average lateral ER was 0.32 (± 0.04) in X-ray and 0.32 (± 0.04) in CT. On the medial side, the average ER was 0.34 (± 0.04) in X-ray and 0.35 (± 0.04) in CT. The interobserver agreement for the same imaging modality was lateral 0.81 and medial 0.81 in X-ray as well as lateral 0.74 and medial 0.85 in CT. The correlation between the two methods was lateral 0.81 and medial 0.79. CONCLUSIONS: The ER can be reliably determined in X-ray and CT. Measurements of the two image modalities correlate. Prior to rTKA, the sole use of the X-ray is possible.

[Acetabular Revision: Reconstruction of Cavitary and Segmental Defects with Special Consideration of Modular Highly Porous Acetabular Revision Systems]. / Azetabuläre Revision: Rekonstruktion kavitärer und segmentaler Defekte unter besonderer Berücksichtigung modularer hoch poröser Pfannensysteme.

Due to the increasing number of primary hip arthroplasty procedures, revision surgery will be an increasing challenge. The surgeon is frequently confronted with important acetabular defects. Careful preoperative planning is essential to achieve functional and long-term success. Treatment options include porous hemispheric cups, porous metal augments, oblong cups, cemented implants, rings, allografts, patient specific implants and component combinations. In addition to large hemispherical cups, modular porous metal revision systems are increasingly being used to treat severe acetabular bone loss. This article provides an overview of relevant literature and implant-specific features of different reconstruction strategies.

The epicondylar ratio can be reliably used on X-ray of the knee to determine the joint line.

PURPOSE: The epicondylar ratio (ER) is used to restore the individual joint line (JL), especially in revision total knee arthroplasty. It was first described in magnetic resonance imaging (MRI) but is usually applied to a.p. radiographs of the knee for preoperative planning. The objective of the current study was to define reliable landmarks in MRI and X-ray images of the knee, which allow comparison of the image modalities. Furthermore, the correlation of the measured ER in MRI and X-rays of the knee was calculated. METHODS: A consecutive series of 87 patients who underwent an arthroscopical intervention of the knee were included into the present study. The lateral epicondyle was defined as the most lateral and distal prominence. On the medial side, the measurement was aligned to the epicondylar sulcus. The medial and lateral ER were calculated by dividing the perpendicular distance from the JL to the epicondyle by the transepicondylar distance. One observer determined the ER twice to calculate the intramethod intraobserver agreement, and a second observer obtained the intramethod interobserer agreement. The ER obtained from X-ray and MRI was compared to calculate the intermethod correlation. RESULTS: The average lateral ER was 0.29 on X-ray versus 0.28 on MRI. The average medial ER was 0.33 and 0.33, respectively. Intramethod agreement ranged from 0.66 to 0.88 and intermethod correlation from 0.49 to 0.57. CONCLUSIONS: The ER can be determined reliably on MRI and X-ray images of the knee. The correlation of the ER in MRI and X-ray is fair.