Biomechanical comparison of acetabular fracture fixation with stand-alone THA or in combination with plating

Biomechanical analysis of a short femoral stem used in revision total hip replacement of a standard femoral stem

Short-stem total hip arthroplasty (SHA) has become popular because it preserves femoral bone stock and enables the use of short femoral stems in revision total hip arthroplasty (THA). However, no study has evaluated whether a short stem in revision THA, replacing a standard stem, can provide adequate primary stability to facilitate osseous integration. In this biomechanical study, a metaphyseal anchoring SHA (Tri-Lock BPS) stem and a standard THA (Corail) stem were implanted into ten composite femurs and loaded dynamically from 300 to 1700 N with 1 Hz. Primary stability was estimated using three-dimensional (3D) micromotions at five points around the bone-implant interface. A revision scenario was then established by removing the standard stem and implanting the same Tri-Lock BPS stem, with subsequent measurements of 3D micromotions. In the primary scenario, no significant differences in 3D micromotions were noted between the short and standard stems at most of the test points. Compared with the Corail group, the Tri-Lock BPS group presented significantly greater 3D micromotions only at the lateral point of the distal femur (P5: Tri-Lock BPS 32.9 ± 7.54 μm vs. Corail 25.1 ± 4.32 μm; p = 0.011). In the revision scenario, no significant differences in the 3D micromotions were noted between the primary and revision Tri-Lock BPS stems at all test points. Our results show that the SHA (Tri-Lock BPS) offers good primary stability, which is similar to that of the standard THA (Corail). The Tri-Lock BPS stem obtained comparable stability in this revision scenario as in the primary scenario; therefore, it can be assumed that the Corail standard stem can safely be revised with a Tri-Lock BPS short stem.

Antegrade Posterior Column Acetabulum Fracture Screw Fixation via Posterior Approach: A Biomechanical Comparative Study

Background and Objectives: Minimally invasive surgeries for acetabulum fracture fixation are gaining popularity due to their known advantages versus open reduction and internal fixation. Antegrade or retrograde screw fixation along the long axis of the posterior column of the acetabulum is increasingly applied in surgical practice. While there is sufficient justification in the literature for the application of the anterior approach, there is a deficit of reports related to the posterior approach. The aim of this study was to evaluate the biomechanical competence of posterior column acetabulum fracture fixation through antegrade screw placement using either a standard cannulated screw or a cannulated compression headless screw (CCHS) via posterior approach. Materials and Methods: Eight composite pelvises were used, and a posterior column acetabulum fracture according to the Letournel Classification was simulated on both their left and right sides via an osteotomy. The sixteen hemi-pelvic specimens were assigned to two groups (n = 8) for either posterior column standard screw (group PCSS) or posterior column CCHS (group PCCH) fixation. Biomechanical testing was performed by applying steadily increased cyclic load until failure. Interfragmentary movements were investigated by means of motion tracking. Results: Initial stiffness demonstrated significantly higher values in PCCH (163.1 ± 14.9 N/mm) versus PCSS (133.1 ± 27.5 N/mm), p = 0.024. Similarly, cycles and load at failure were significantly higher in PCCH (7176.7 ± 2057.0 and 917.7 ± 205.7 N) versus PCSS (3661.8 ± 1664.5 and 566.2 ± 166.5 N), p = 0.002. Conclusion: From a biomechanical perspective, CCHS fixation demonstrates superior stability and could be a valuable alternative option to the standard cannulated screw fixation of posterior column acetabulum fractures, thus increasing the confidence in postoperative full weight bearing for both the patient and treating surgeon. Whether uneventful immediate postoperative full weight bearing can be achieved with CCHS fixation should primarily be investigated in further human cadaveric studies with a larger sample size.

Simulated full weight bearing following posterior column acetabular fracture fixation: a biomechanical comparability study

PURPOSE

The incidence of acetabular fractures (AFs) is increasing in all industrial nations, with posterior column fractures (PCFs) accounting for 18.5-22% of these cases. Treating displaced AFs in elderly patients is a known challenge. The optimal surgical strategy implementing open reduction and internal fixation (ORIF), total hip arthroplasty (THA), or percutaneous screw fixation (SF), remains debated. Additionally, with either of these treatment methods, the post-surgical weight bearing protocols are also ambiguous. The aim of this biomechanical study was to evaluate construct stiffness and failure load following a PCF fixation with either standard plate osteosynthesis, SF, or using a screwable cup for THA under full weight bearing conditions.

METHODS

Twelve composite osteoporotic pelvises were used. A PCF according to the Letournel Classification was created in 24 hemi-pelvis constructs stratified into three groups (n = 8) as follows: (i) posterior column fracture with plate fixation (PCPF); (ii) posterior column fracture with SF (PCSF); (iii) posterior column fracture with screwable cup fixation (PCSC). All specimens were biomechanically tested under progressively increasing cyclic loading until failure, with monitoring of the interfragmentary movements via motion tracking.

RESULTS

Initial construct stiffness (N/mm) was 154.8 ± 68.3 for PCPF, 107.3 ± 41.0 for PCSF, and 133.3 ± 27.5 for PCSC, with no significant differences among the groups, p = 0.173. Cycles to failure and failure load were 7822 ± 2281 and 982.2 ± 428.1 N for PCPF, 3662 ± 1664 and 566.2 ± 366.4 N for PCSF, and 5989 ± 3440 and 798.9 ± 544.0 N for PCSC, being significantly higher for PCPF versus PCSF, p = 0.012.

CONCLUSION

Standard ORIF of PCF with either plate osteosynthesis or using a screwable cup for THA demonstrated encouraging results for application of a post-surgical treatment concept with a full weight bearing approach. Further biomechanical cadaveric studies with larger sample size should be initiated for a better understanding of AF treatment with full weight bearing and its potential as a concept for PCF fixation.

Managing periprosthetic fractures: perspectives on periprosthetic pelvic fractures

Periacetabular periprosthetic fractures are rare but potentially disastrous for the longevity of the adjacent implants, leading to multiple revision surgeries. It is of paramount importance to identify and treat intraoperative fractures, which will lead to satisfactory results. Postoperative fractures may be managed operatively or nonoperatively depending on the patient's pain and function, the fracture pattern, and the stability of the acetabular component.

[Techniques and results of primary hip arthroplasty in geriatric acetabular fractures]

As a result of demographic changes, there is an increase in geriatric acetabular fractures [1, 2]. Geriatric patients often have comorbidities, such as pre-existing coxarthritis, reduced bone quality or limited compliance, which makes injury-adapted follow-up treatment difficult [3]. As a result joint-preserving interventions often fail at an early stage, so that hip arthroplasty is necessary in the short term. The 1‑year mortality after surgically stabilized acetabular fractures is 8.1%, a significant increase by a factor of 4 compared to the age group [4]. This illustrates that differentiated criteria for the indication of joint-preserving surgery versus arthroplasty are necessary to avoid reoperations and complications. Criteria for the indications for primary arthroplasty are fracture type, pre-existing coxarthritis, poor bone quality, limited compliance and patient age (> 75 years) [5, 6].In the following article, three treatment strategies for geriatric acetabular fractures and periprosthetic acetabular fractures are presented; the 1‑stage prosthesis implantation without osteosynthesis, the 1‑stage prosthesis implantation with osteosynthesis and the 2‑stage approach with limited osteosynthesis and early total arthroplasty. The advantages and disadvantages of these options are presented based on cases and the various aspects of the treatment. The treatment of geriatric acetabular fractures is an operative challenge for the surgeon and requires a high level of expertise in both special trauma surgery and revision arthroplasty and thus represents a special interface in the fields of orthopedics and trauma surgery.

Effects of Different Surgical Procedures on the Therapeutic Effects, Prognosis, and Major Complications of Acetabular Fractures in the Elderly of China: A Systematic Review and Meta-Analysis

Objective. Different surgical approaches were systematically evaluated to provide an evidence-based medical rationale for the application and promotion of acetabular fractures in the elderly of China. Methods. Randomized controlled trials (RCT) of different surgical methods in the treatment of elderly acetabular fractures were searched in the PubMed, EMBASE, ScienceDirect, Cochrane Library, China Knowledge Network Database (CNKI), China VIP Database, Wanfang Database, and China Biomedical Literature Database (CBM). The search time threshold was set from the time the database was created to the current time. Investigators obtained data independently, and the bias risk of each included writing was reviewed using the Cochrane Manual 5.1.0 criterion. The meta data was analyzed using RevMan 5.4 statistical package. Results. 6 RCT articles were included in the end. A total of 445 samples were analyzed by meta. All the six RCT literatures included in this meta-analysis reported the baseline status of patients, only 3 RCT mentioned “random assignment” without any explanation, and the rest did not mention “random” information. The five studies included all gave detailed intervention measures. The number and reasons of blind method and lost follow-up or withdrawal were not described in detail in 6 RCT articles. Through the meta-analysis excellent and good rate between the experimental group and the control group through 6 RCT studies, the heterogeneity test results were $\text{ch}{\text{i}}^2=6.11$ , $\text{df}=4$ , $\text{P}=0.19>0.05$ , and ${\text{I}}^2=35\%$ , without obvious heterogeneity at $Z=2.68$ and $P=0.007$ . These results suggested that the total hip arthroplasty application has the same excellent rate as other surgical treatment methods, indicating that total hip arthroplasty has a significant effect on the treatment of elderly acetabular fractures. Through the meta-analysis hip-joint function score, the heterogeneity test results were $\text{ch}{\text{i}}^2=56.16$ , $\text{df}=4$ , $P<0.00001$ , and $I^2=93\%$ , with obvious heterogeneity. The great difference was discovered in hip function score between total hip arthroplasty and other surgical methods, showing that total hip arthroplasty can greatly improve hip-joint function. Then, the incidence of hip complications between the experimental cases and the control cases was calculated by meta. The heterogeneity test results were $\text{ch}{\text{i}}^2=3.17$ , $\text{df}=4$ , $P=0.53>0.05$ , and $I^2=0\%$ , without remarkable heterogeneity at $Z=3.05$ and $P=0.002$ . This demonstrated that a significant difference was observed in the complication incidence, indicating that total hip arthroplasty displayed a lower incidence of hip-joint functional complications. Conclusion. Total hip arthroplasty has a good prognosis and a low complication rate in the treatment of acetabular fractures in the elderly. However, more studies and longer follow-ups are needed to further validate the findings of this study.