Reduced rates of non-union with modified periacetabular osteotomy using peracetic-acid sterilized cancellous allografts

Periacetabular Osteotomy with a Modified Fixation Technique Using K-Wires Shows Clinical Results Comparable to Screw Fixation at Mid-Term Follow-Up

BACKGROUND

The optimal fixation technique in periacetabular osteotomy (PAO) remains controversial. Modified fixation with Kirschner wires (K-wires) was described as a feasible and safe alternative. However, clinical follow-up of patients treated with this technique is lacking.

AIMS

To assess patient-reported outcomes (PROMs) in patients treated with PAO with the K-wire fixation technique and to compare it with the screw fixation technique.

METHODS

We conducted an analysis of 202 consecutive PAOs at a single university center between January 2015 and June 2017. A total of 120 cases with complete datasets were included in the final analysis. PAOs with K-wire fixation (n = 63) were compared with screw fixation (n = 57). Mean follow-up was 63 ± 10 months. PROMs assessed included the International Hip Outcome Tool (iHOT 12), Subjective Hip Value (SHV), and UCLA activity score (UCLA). Pain and patient satisfaction (NRS) were evaluated. Joint preservation was defined as non-conversion to total hip arthroplasty (THA).

RESULTS

Preoperative baseline PROMs in both fixation groups were similar. In both groups, PROMs (p = <0.001) and pain (p = <0.001) improved significantly. Postoperative functional outcome was similar in both groups: iHOT 12 (71.8 ± 25.1 vs. 73 ± 21.1; p = 0.789), SHV (77.9 ± 21.2 vs. 82.4 ± 13.1; p = 0.192), UCLA (6.9 ± 1.6 vs. 6.9 ± 1.9; p = 0.909), and pain (2.4 ± 2.1 vs. 2.0 ± 2.1; p = 0.302). Patient satisfaction did not differ significantly (7.6 ± 2.6 vs. 8.2 ± 2.2; p = 0.170). Conversion to THA was low in both groups (two vs. none; p = 0.497).

CONCLUSION

Periacetabular osteotomy with K-wire fixation provided good clinical results at mid-term follow-up, comparable to those of screw fixation. The technique can therefore be considered a viable option when deciding on the fixation technique in PAO.

[Fixation techniques in periacetabular osteotomy : Stability and clinical aspects of established and new fixation techniques]

Periacetabular osteotomy according to Ganz (PAO) is an established technique for the surgical treatment of hip dysplasia with the aim of biomechanically optimizing the dysplastic hip joint. Through multidimensional reorientation, the deficient coverage of the femoral head can be improved and physiological values can be achieved. Until bony consolidation is reached, adequate fixation of the acetabulum in the corrected position achieved is necessary. Various fixation techniques are available for this purpose. Alternatively to screws, Kirschner wires can also be used for fixation. The different fixation techniques show comparable stability. Differences exist in the occurrence of implant-associated complications. However, there is no difference in patient satisfaction and joint-specific function.

Fixation stability and implant-associated complications in periacetabular osteotomy: a comparison of screw and K-wire fixation

AIMS

The aim of this study was to compare the fixation stability and complications in patients undergoing periacetabular osteotomy (PAO) with either K-wire or screw fixation.

PATIENTS AND METHODS

We performed a retrospective study to analyze a consecutive series of patients who underwent PAO with either screw or K-wire fixation. Patients who were treated for acetabular retroversion or had previous surgery on the ipsilateral hip joint were excluded. 172 patients (191 hips: 99 K-wire/92 screw fixation) were included. The mean age at the time of PAO was 29.3 years (16-48) in the K-wire group and 27.3 (15-45) in the screw group and 83.9% were female. Clinical parameters including duration of surgery, minor complications (soft tissue irritation and implant migration) and major complications (implant failure and non-union) were evaluated. Radiological parameters including LCE, TA and FHEI were measured preoperatively, postoperatively and at 3-months follow-up.

RESULTS

Duration of surgery was significantly reduced in the K-wire group with 88.2 min (53-202) compared to the screw group with 119.7 min (50-261) (p < 0.001). Soft tissue irritation occurred significantly more often in the K-wire group (72/99) than in the screw group (36/92) (p < 0.001). No group showed significantly more implant migration than the other. No major complications were observed in either group. Postoperative LCE, TA and FHEI were improved significantly in both groups for all parameters (p = < 0.0001). There was no significant difference for initial or final correction for the respective parameters between the two groups. Furthermore, no significant difference in loss of correction was observed between the two groups for the respective parameters.

CONCLUSION

K-wire fixation is a viable and safe option for fragment fixation in PAO with similar stability and complication rates as screw fixation. An advantage of the method is the significantly reduced operative time. A disadvantage is the significantly higher rate of implant-associated soft tissue irritation, necessitating implant removal.

LEVEL OF EVIDENCE

III, retrospective trial.

Periacetabular Osteotomy and Postoperative Pregnancy—Is There an Influence on the Mode of Birth?

As a surgical treatment option in symptomatic developmental dysplasia of the hip, periacetabular osteotomy (PAO) is often performed in female patients of childbearing age. Yet, to date, little is known about the procedure’s influence on postoperative pregnancies and the mode of delivery. Our study’s aim therefore was to investigate patient and physician decision making in women after PAO. We invited all patients who had undergone PAO in our institution from January 2015 to June 2017 to participate in a paper-based survey. Of these, we included all female patients and performed a retrospective chart review as well as analysis of pre- and postoperative radiological imaging. A total of 87 patients were included, 20 of whom gave birth to 26 children after PAO. The mean overall follow-up was 5.3 ± 0.8 years. Four (20.0%) patients reported that their obstetrician was concerned due to their history of PAO. The mean time before the first child’s birth was 2.9 ± 1.3 years. Eleven (55.0%) patients underwent cesarean section for the first delivery after PAO, three of whom reported their history of PAO as the reason for this type of delivery. Patients with a history of PAO have a higher risk of delivering a child by cesarean section compared with the general population, in which the rate of cesarean section is reported to be 29.7%. As cesarean sections are associated with increased morbidity and mortality compared with vaginal deliveries, evidence-based recommendations for pregnancies after pelvic osteotomy are needed.

[Minimally invasive periacetabular osteotomy for adult hip dysplasia]

OBJECTIVE

Performance of a periacetabular osteotomy (PAO) using a minimally invasive approach for three-dimensional correction of the acetabular position.

INDICATIONS

Symptomatic developmental dysplasia of the hip in adolescents and adults.

CONTRAINDICATIONS

Advanced osteoarthritis of the hip, incongruence of the hip joint surfaces.

SURGICAL TECHNIQUE

A periacetabular osteotomy is performed via a minimally invasive approach.

RESULTS

In total, 39 patients were followed up for 3.5 (3-4.5) years. The lateral center-edge angle of Wiberg increased significantly from 16.1° (7-24°) to 30.5° (25-37°) (p < 0.0001), the acetabular index changed from 13.2° (2-25.3°) to 2.8° (-3-13°; p < 0.0001). Mean duration of surgery was 88 (57-142) minutes. No major complications occurred.

Case Report: Intraarticular Iliopsoas Tendon causes Groin Pain Following Periacetabular Osteotomy

A 43-year-old female patient reported persistent iliopsoas-related groin pain following periacetabular osteotomy (PAO) combined with femoroplasty via a direct anterior approach due to CAM morphology. Concomitantly with the planned removal of screws, hip arthroscopy was performed, and the iliopsoas tendon was found to run intraarticularly, resulting in the tendon being impaired in its mobility and being entrapped. The tendon was arthroscopically released. The patient reported relief of the groin pain after the arthroscopic tendon debridement. During PAO combined with capsulotomy, the postoperatively observed intraarticular position of the iliopsoas tendon should be prevented by careful closure of the joint capsule.

Is transverse screw fixation really necessary in PAO?-A comparative in vivo study

The optimal fixation technique in periacetabular osteotomy (PAO) remains controversial. This study aims to assess the in vivo stability of fixation in PAO with and without the use of a transverse screw. We performed a retrospective study to analyse consecutive patients who underwent PAO between January 2015 and June 2017. Eighty four patients (93 hips) of which 79% were female were included. In 54 cases, no transverse screw was used (group 1) compared with 39 with transverse screw (group 2). Mean age was 26.5 (15–44) in group 1 and 28.4 (16–45) in group 2. Radiological parameters relevant for DDH including lateral center edge angle of Wiberg (LCEA), Tönnis angle (TA) and femoral head extrusion index (FHEI) were measured preoperatively, post-operatively and at 3-months follow-up. All patients were mobilized with the same mobilization regimen. Post-operative LCEA, TA and FHEI were improved significantly in both groups for all parameters (P ≤ 0.0001). Mean initial correction for LCEA (P = 0.753), TA (P = 0.083) and FHEI (P = 0.616) showed no significant difference between the groups. Final correction at follow-up of the respective parameters was also not significantly different between both groups for LCEA (P = 0.447), TA (P = 0.100) and FHEI (P = 0.270). There was no significant difference between initial and final correction for the respective parameters. Accordingly, only minimal loss of correction was measured, showing no difference between the two groups for LCEA (P = 0.227), TA (P = 0.153) and FHEI (P = 0.324). Transverse screw fixation is not associated with increased fragment stability in PAO. This can be taken into account by surgeons when deciding on the fixation technique of the acetabular fragment in PAO.

Peracetic Acid-Ethanol Processed Human Tendon Allograft: A Morphological, Biochemical, and Biomechanical Study In Vitro

OBJECTIVE

To clarify the morphological, biochemical, and biomechanical effects of peracetic acid-ethanol sterilization processing to human hamstring tendon allografts for different time periods.

METHODS

Thirty-two fresh-frozen human hamstring tendon allografts obtained from an allograft supplier were prepared and incubated in peracetic acid-ethanol solution (PES) containing 1% v/v peracetic acid and 24% v/v ethanol. Specimens were randomly classified into four groups according to the PES processing time (untreated as the control group, 30 min as the PES30 group, 120 min as the PES120 group, and 240 min as the PES240group). Light microscopy with hematoxylin-eosin and toluidine blue were performed, along with transmission electron microscopy (TEM) to measure the collagen fibril diameters and their distributions, from which the collagen fibril index (CFI) and mass average diameter (MAD) were calculated. The thermal stability and collagen denaturation were analyzed by differential scanning calorimetry (DSC) and collagen denaturation test by α-chymotrypsin. Cyclic loading and failure testing were applied on five tendons from each group, from which the cyclic creep strain, elastic modulus, maximum stress, maximum strain, and strain energy density were calculated.

RESULTS

Tendons in the control, PES30, PES120 groups showed similar regularly aligned collagen fibers in light microscopy images, while the images from the PES240 group revealed relatively disordered and heterogeneous collagen bundles with larger interfiber spaces. TEM analysis showed that the mean diameter (F = 3.09, P = 0.04) was lower in the PES120 group (87.15 ± 4.76 nm) than it was in the control group (99.39 ± 9.19 nm) but not statistically (P = 0.05). Moreover, the CFI value in the PES30 group (65.37 ± 4.14%) was the lowest among groups (all P ≤ 0.01), while no variance existed in density and MAD among groups (F = 2.09, P = 0.13, and F = 0.27, P = 0.85, respectively). The onset temperature (H = 8.74, P = 0.03) and peak temperature (H = 9.97, P = 0.02) were decreased in the PES30 group compared to the control group (P = 0.02 and P = 0.01, respectively), but there were no differences in enthalpy of denaturation among groups (F = 2.20, P = 0.17). The collagen denaturation test revealed lower hydroxyproline concentrations in PES-treated specimens with no statistical differences among groups (H = 8.86, P = 0.07). The maximum stress showed variance (F = 10.52, P < 0.01) that it was higher in PES30 group (68.29 ± 10.86 MPa) compared to the PES120 and the PES240 group, while it was lower in the PES120 group (19.40 ± 4.94 MPa) compared to the control and the PES30 group (all P < 0.05). The strain energy density (F = 7.34, P < 0.01) was over 4 times higher in the PES30 group (7.39 ± 2.51 MPa) than it was in the PES120 group (1.56 ± 0.64 MPa, P < 0.01).

CONCLUSION

PES treatment for 30 min has no adverse effect on the properties of human hamstring tendon allografts, longer processing time could not promise better properties preservation.

Metal-Specific Biomaterial Accumulation in Human Peri-Implant Bone and Bone Marrow

Metallic implants are frequently used in medicine to support and replace degenerated tissues. Implant loosening due to particle exposure remains a major cause for revision arthroplasty. The exact role of metal debris in sterile peri-implant inflammation is controversial, as it remains unclear whether and how metals chemically alter and potentially accumulate behind an insulating peri-implant membrane, in the adjacent bone and bone marrow (BM). An intensively focused and bright synchrotron X-ray beam allows for spatially resolving the multi-elemental composition of peri-implant tissues from patients undergoing revision surgery. In peri-implant BM, particulate cobalt (Co) is exclusively co-localized with chromium (Cr), non-particulate Cr accumulates in the BM matrix. Particles consisting of Co and Cr contain less Co than bulk alloy, which indicates a pronounced dissolution capacity. Particulate titanium (Ti) is abundant in the BM and analyzed Ti nanoparticles predominantly consist of titanium dioxide in the anatase crystal phase. Co and Cr but not Ti integrate into peri-implant bone trabeculae. The characteristic of Cr to accumulate in the intertrabecular matrix and trabecular bone is reproducible in a human 3D in vitro model. This study illustrates the importance of updating the view on long-term consequences of biomaterial usage and reveals toxicokinetics within highly sensitive organs.

[Bone banks : The state-of-the-art]

Bone banks are responsible for the collection, production, testing, packaging, storage and delivery of osseous grafts. In compliance with legal and quality requirements, it is their main task to ensure the biological properties and the microbiological safety of the transplants as well. German legal requirements for bone banking are explained and current standards with respect to donor selection, laboratory tests and tissue processing, as well as labeling are discussed. Production and preparation procedures should include a validated microbiological inactivation method that largely preserves the biological properties of the tissue.