An innovative procedure for the development of 3D patient-specific implants with drilling guides for acetabular fracture surgery is presented. By using CT data and 3D surgical planning software, a ...virtual model of the fractured pelvis was created. During this process the fracture was virtually reduced. Based on the reduced fracture model, patient-specific titanium plates including polyamide drilling guides were designed, 3D printed and milled for intra-operative use. One of the advantages of this procedure is that the personalised plates could be tailored to both the shape of the pelvis and the type of fracture. The optimal screw directions and sizes were predetermined in the 3D model. The virtual plan was translated towards the surgical procedure by using the surgical guides and patient-specific osteosynthesis. Besides the description of the newly developed multi-disciplinary workflow, a clinical case example is presented to demonstrate that this technique is feasible and promising for the operative treatment of complex acetabular fractures.
Background
Since its first description in 1984, periacetabular osteotomy (PAO) has become an accepted treatment for hip dysplasia. The 30-year survivorship with this procedure has not been reported. ...Because these patients are often very young at the time of surgery, long-term followup and identification of factors associated with poor outcome could help to improve patient selection.
Questions/purposes
Looking at the initial group of patients with hip dysplasia undergoing PAO at the originator’s institution, we asked: (1) What is the cumulative 30-year survival rate free from conversion to THA, radiographic progression of osteoarthritis, and/or a Merle d’Aubigné-Postel score < 15? (2) Did hip function improve and pain decrease? (3) Did radiographic osteoarthritis progress? (4) What are the factors associated with one or more of the three endpoints: THA, radiographic progression of osteoarthritis, and/or Merle d’Aubigné-Postel score < 15?
Methods
We retrospectively evaluated the first 63 patients (75 hips) who underwent PAO for hip dysplasia between 1984 and 1987. At that time, hip dysplasia was the only indication for PAO and no patients with acetabular retroversion, the second indication for a PAO performed today, were included. During that period, no other surgical treatment for hip dysplasia in patients with closed triradiate cartilage was performed. Advanced osteoarthritis (≥ Grade 2 according to Tönnis) was present preoperatively in 18 hips (24%) and 22 patients (23 hips 31%) had previous femoral and/or acetabular surgery. Thirty-nine patients (42 hips 56%) were converted to a THA and one patient (one hip 1%) had hip fusion at latest followup. Two patients (three hips 4%) died from a cause unrelated to surgery 6 and 16 years after surgery with an uneventful followup. From the remaining 21 patients (29 hips), the mean followup was 29 years (range, 27–32 years). Of those, five patients (six hips 8%) did not return for the most recent followup and only a questionnaire was available. The cumulative survivorship of the hip according to Kaplan-Meier was calculated if any of the three endpoints, including conversion to THA, progression of osteoarthritis by at least one grade according to Tönnis, and/or a Merle d’Aubigné-Postel score < 15, occurred. Hip pain and function were assessed with Merle d’Aubigné-Postel score, Harris hip score, limp, and anterior and posterior impingement tests. Progression of radiographic osteoarthritis was assessed with Tönnis grades. A Cox regression model was used to calculate factors associated with the previously defined endpoints.
Results
The cumulative survivorship free from conversion to THA, radiographic progression of osteoarthritis, and/or Merle d’Aubigné-Postel score < 15 was 29% (95% confidence interval, 17%-42%) at 30 years. No improvement was found for either the Merle d’Aubigné-Postel (15 ± 2 versus 16 ± 2, p = 0.144) or Harris hip score (83 ± 11 versus 85 ± 17, p = 0.602). The percentage of a positive anterior impingement test (39% versus 14%, p = 0.005) decreased at 30-year followup, whereas the percentage of a positive posterior impingement test (14% versus 3%, p = 0.592) did not decrease. The percentage of positive limp decreased from preoperatively 66% to 18% at 30-year followup (p < 0.001). Mean osteoarthritis grade (Tönnis) increased from preoperatively 0.8 ± 1 (0–3) to 2.1 ± 1 (0–3) at 30-year followup (p < 0.001). Ten factors associated with poor outcome defined as THA, radiographic progression of osteoarthritis, and/or Merle d’Aubigné-Postel score < 15 were found: preoperative age > 40 years (hazard ratio HR 4.3 3.7–4.9), a preoperative Merle d’Aubigné-Postel score < 15 (HR 4.1 3.5–4.6), a preoperative Harris hip score < 70 (HR 5.8 5.2–6.4), preoperative limp (HR 1.7 1.4–1.9), presence of a preoperative positive anterior impingement test (HR 3.6 3.1–4.2), presence of a preoperative positive posterior impingement test (HR 2.5 1.7–3.2), a preoperative internal rotation of < 20° (HR 4.3 3.7–4.9), a preoperative Tönnis Grade > 1 (HR 5.7 5.0–6.4), a postoperative anterior coverage > 27% (HR 3.2 2.5–3.9), and a postoperative acetabular retroversion (HR 4.8 3.4–6.3).
Conclusions
Thirty years postoperatively, 29% of hips undergoing PAO for hip dysplasia can be preserved, but more than 70% will develop progressive osteoarthritis, pain, and/or undergo THA. Periacetabular osteotomy is an effective technique to treat symptomatic hip dysplasia in selected and young patients with closed triradiate cartilage. Hips with advanced joint degeneration (osteoarthritis Tönnis Grade ≥ 2) should not be treated with PAO. Postoperative anterior acetabular overcoverage or postoperative acetabular retroversion were associated with decreased joint survival.
Level of Evidence
Level III, therapeutic study.
Background
The Bernese periacetabular osteotomy (PAO) continues to be a commonly performed nonarthroplasty option to treat symptomatic developmental hip dysplasia, but there are few long-term ...followup studies evaluating results after PAO.
Questions/purposes
(1) What is the long-term survivorship of the hip after PAO? (2) What were the validated outcomes scores among patients who had PAO more than 14 years ago? (3) What factors are associated with long-term failure?
Methods
One hundred fifty-eight dysplastic hips (133 patients) underwent PAO between May 1991 and September 1998 by a single surgeon. Of those, 37 hips (34 patients 26%) were lost to followup; an additional seven patients (5% eight hips) had not been seen in the last 5 years. The 121 hips (in 99 patients) were retrospectively evaluated at a mean of 18 years (range, 14–22 years). Survivorship was assessed using Kaplan-Meier analysis with total hip arthroplasty (THA) as the endpoint. Hips were evaluated for activity, pain, and general health using the UCLA Activity Score, modified Harris hip score, WOMAC, and Hip disability and Osteoarthritis Outcome Score (HOOS). Failure was defined as a WOMAC pain subscale score ≥ 10 or having undergone THA. Hips were divided into three groups: asymptomatic (did not meet any failure criteria at any point in time), symptomatic (met WOMAC pain failure criteria at previous or most recent followup), and replaced (having undergone THA). A multinomial logistic regression model using a general estimating equations approach was used to assess factors associated with failure.
Results
Kaplan-Meier analysis with THA as the endpoint revealed a survival rate (95% confidence interval CI) of 74% (66%–83%) at 18 years. Twenty-six hips (21%) underwent THA at an average of 9 ± 5 years from the surgery. Sixty-four hips (53%) remained asymptomatic and did not meet any failure criteria at most recent followup. Thirty-one hips (26%) were symptomatic and considered failed based on a WOMAC pain score of ≥ 10 with a mean ± SD of 11 ± 4 out of 20 at most recent followup. Although some failed initially by pain, their most recent WOMAC score may have been < 10. Of the 16 symptomatic hips that failed early by pain (reported a WOMAC pain subscale score ≥ 10 in the prior study), two were lost to followup, two underwent THA at 16 and 17 years, four still failed because of pain at most recent followup, and the remaining eight had WOMAC pain scores < 10 at most recent followup. Asymptomatic hips reported better UCLA Activity Scores (asymptomatic: mean ± SD, 7 ± 2; symptomatic: 6 ± 2, p = 0.001), modified Harris hip scores (pain, function, and activity sections; asymptomatic: 80 ± 11; symptomatic: 50 ± 15, p < 0.001), WOMAC (asymptomatic: 2 ± 2, symptomatic: 11 ± 4, p < 0.001), and HOOS (asymptomatic: 87 ± 11, symptomatic: 52 ± 20, p < 0.001) compared with symptomatic hips at long-term followup. Age older than 25 years at the time of PAO (symptomatic: odds ratio OR, 3.6; 95% CI, 1.3–9.8; p = 0.01; replaced: OR, 8.9; 95% CI, 2.6–30.9; p < 0.001) and a preoperative joint space width ≤ 2 mm (replaced: OR, 0.3; 95% CI, 0.12–0.71; p = 0.007) or ≥ 5 mm (replaced: OR, 0.121; 95% CI, 0.03–0.56; p = 0.007) were associated with long-term failure while controlling for poor or fair preoperative joint congruency.
Conclusions
This study demonstrates the durability of the Bernese PAO at long-term followup. In a subset of patients, there was progression to failure over time. Factors of progression to THA or more severe symptoms include age older than 25 years, poor or fair preoperative hip congruency, and a preoperative joint space width that is less than 2 mm or more than 5 mm. Future studies should focus on evaluating the two failure groups that we have identified in our study: those that failed early and went on to THA and those that are symptomatic at long-term followup.
Level of Evidence
Level III, therapeutic study.
Antegrade fixation of posterior column fractures of the acetabulum is challenging due to the narrow corridor and risk of screw misplacement. Although both antegrade and retrograde lag screws have ...been previously described for posterior column fracture fixation, the literature lacks a standardized technique for correct and safe screw placement, especially in an antegrade fashion. This technical note aims to optimize intraoperative images during posterior screw insertion using the antegrade technique, according to predetermined landmarks to save surgical time, decrease radiation exposition, and prevent surgical complications.
Background
Detailed recognition of the three-dimensional (3-D) deformity in acetabular dysplasia is important to help guide correction at the time of reorientation during periacetabular osteotomy ...(PAO). Common plain radiographic parameters of acetabular dysplasia are limited in their ability to characterize acetabular deficiency precisely. The 3-D characterization of such deficiencies with low-dose CT may allow for more precise characterization.
Questions/purposes
The purposes of this study were (1) to determine the variability in 3-D acetabular deficiency in acetabular dysplasia; (2) to define subtypes of acetabular dysplasia based on 3-D morphology; (3) to determine the correlation of plain radiographic parameters with 3-D morphology; and (4) to determine the association of acetabular dysplasia subtype with patient clinical characteristics including sex, range of motion, and femoral version.
Methods
Using our hip preservation database, we identified 153 hips (148 patients) that underwent PAO from October 2013 to July 2015. Among those, we noted 103 hips in 100 patients with acetabular dysplasia (lateral center-edge angle < 20°) and who had a Tönnis grade of 0 or 1. Eighty-six patients (86%) underwent preoperative low-dose pelvic CT scans at our institution as part of the preoperative planning for PAO. It is currently our standard to obtain preoperative low-dose pelvic CT scans (0.75–1.25 mSv, equivalent to three to five AP pelvis radiographs) on all patients before undergoing PAO unless a prior CT scan was performed at an outside institution. Hips with a history of a neuromuscular disorder, prior trauma, prior surgery, radiographic evidence of joint degeneration, ischemic necrosis, or Perthes-like deformities were excluded. Fifty hips in 50 patients met inclusion criteria and had CT scans available for review. These low-dose CT scans of 50 patients with symptomatic acetabular dysplasia undergoing evaluation for surgical planning of PAO were then retrospectively studied. CT scans were analyzed quantitatively for acetabular coverage, relative to established normative data for acetabular coverage, as well as measurement of femoral version. The cohort included 45 females and five males with a mean age of 26 years (range, 13–49 years).
Results
Lateral acetabular deficiency was present in all patients, whereas anterior deficiency and posterior deficiency were variable. Three patterns of acetabular deficiency were common: anterosuperior deficiency (15 of 50 30%), global deficiency (18 of 50 36%), and posterosuperior deficiency (17 of 50 34%). The presence of a crossover sign or posterior wall sign was poorly predictive of the dysplasia subtype. With the numbers available, males appeared more likely to have a posterosuperior deficiency pattern (four of five 80%) compared with females (13 of 45 29%, p = 0.040). Hip internal rotation in flexion was significantly greater in anterosuperior deficiency (23° versus 18°, p = 0.05), whereas external rotation in flexion was significantly greater in posterosuperior deficiency (43° versus 34°, p = 0.018). Acetabular deficiency pattern did not correlate with femoral version, which was variable across all subtypes.
Conclusions
Three patterns of acetabular deficiency commonly occur among young adult patients with mild, moderate, and severe acetabular dysplasia. These patterns include anterosuperior, global, and posterosuperior deficiency and are variably observed independent of femoral version. Recognition of these distinct morphologic subtypes is important for diagnostic and surgical treatment considerations in patients with acetabular dysplasia to optimize acetabular correction and avoid femoroacetabular impingement.
Displaced transverse acetabular fractures are unstable injuries that frequently require repair. Although multiple approaches, techniques, and fixation constructs have been described to treat this ...pattern, achieving an anatomical reduction and applying fixation to maintain this until union remains the goal of treatment. We present a surgical technique for transverse or transverse/posterior wall acetabular fractures repaired using a clamp-assisted reduction through the sciatic notch, followed by anterior column screw fixation and subsequent posterior column plating through a Kocher-Langenbeck exposure. We review a case series of 55 patients treated with this technique and evaluate reduction quality using postoperative computed tomogram scans to assess for any residual step-off.
Background
Numerous factors influence total hip arthroplasty (THA) stability including surgical approach and soft tissue tension, patient compliance, and component position. One long-held tenet ...regarding component position is that cup inclination and anteversion of 40° ± 10° and 15° ± 10°, respectively, represent a “safe zone” as defined by Lewinnek that minimizes dislocation after primary THA; however, it is clear that components positioned in this zone can and do dislocate.
Questions/purposes
We sought to determine if these classic radiographic targets for cup inclination and anteversion accurately predicted a safe zone limiting dislocation in a contemporary THA practice.
Methods
From a cohort of 9784 primary THAs performed between 2003 and 2012 at one institution, we retrospectively identified 206 THAs (2%) that subsequently dislocated. Radiographic parameters including inclination, anteversion, center of rotation, and limb length discrepancy were analyzed. Mean followup was 27 months (range, 0–133 months).
Results
The majority (58% 120 of 206) of dislocated THAs had a socket within the Lewinnek safe zone. Mean cup inclination was 44° ± 8° with 84% within the safe zone for inclination. Mean anteversion was 15° ± 9° with 69% within the safe zone for anteversion. Sixty-five percent of dislocated THAs that were performed through a posterior approach had an acetabular component within the combined acetabular safe zones, whereas this was true for only 33% performed through an anterolateral approach. An acetabular component performed through a posterior approach was three times as likely to be within the combined acetabular safe zones (odds ratio OR, 1.3; 95% confidence interval CI, 1.1–1.6) than after an anterolateral approach (OR, 0.4; 95% CI, 0.2–0.7; p < 0.0001). In contrast, acetabular components performed through a posterior approach (OR, 1.6; 95% CI, 1.2–1.9) had an increased risk of dislocation compared with those performed through an anterolateral approach (OR, 0.8; 95% CI, 0.7–0.9; p < 0.0001).
Conclusions
The historical target values for cup inclination and anteversion may be useful but should not be considered a safe zone given that the majority of these contemporary THAs that dislocated were within those target values. Stability is likely multifactorial; the ideal cup position for some patients may lie outside the Lewinnek safe zone and more advanced analysis is required to identify the right target in that subgroup.
Level of Evidence
Level III, therapeutic study.
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