Superior Survivorship of Cementless vs Cemented Diaphyseal Fixed Modular Rotating-Hinged Knee Megaprosthesis at 7 Years' Follow-Up

Background

Total knee arthroplasty in the presence of a huge bone and soft-tissue defect is always a challenge. A rotating-hinged (RH) megaprosthesis is indicated for extensive soft-tissue loss with a huge bone defect such as a primary or metastatic neoplasm of the bone, repeat periprosthetic joint infection, or extensive trauma of the knee. However, the reported survivorship of RH megaprostheses is unsatisfactory. The aim of this study was to evaluate the survivorship of megaprostheses and the factors that contribute to implant survival.

Effects of Different Substrates on the Formability and Densification Behaviors of Cemented Carbide Processed by Laser Powder Bed Fusion

Cemented carbide materials are widely applied in cutting tools, drill tools, and mold fabrication due to their superior hardness and wear resistance. Producing cemented carbide parts via the laser powder bed fusion (L-PBF) method has the advantage of fabricating complex structures with a rapid manufacturing speed; however, they were underdeveloped due to their low density and crack formation on the blocks. This work studied the effect of different substrates including 316L substrates, Ni200 substrates, and YG15 substrates on the forming quality of WC-17Co parts fabricated by L-PBF, with the aim of finding the optimal substrate for fabrication. The results revealed that the Ni200 substrates had a better wettability for the single tracks formation than other substrates, and bonding between the built block and the Ni200 substrate was firm without separation during processing with a large range of laser energy inputs. This guaranteed the fabrication of a relatively dense block with fewer cracks. Although the high laser energy input that led to fine crack formation on the blocks formed on the Ni200 substrate, it was found to be better suited to restricting cracks than other substrates.     

骨水泥型加长柄髋关节置换结合股骨近端重建治疗老年不稳定性股骨转子间骨折的临床效果

目的探讨骨水泥型加长柄髋关节置换结合股骨近端重建治疗老年不稳定性股骨转子间骨折的临床效果。方法将40例老年不稳定性股骨转子间骨折患者随机分为骨水泥型加长柄髋关节置换结合股骨近端重建治疗组(研究组,n=20)和股骨近端防旋髓内钉治疗组(对照组,n=20)。分析两组临床疗效。结果研究组手术时间、切口长度长于对照组,术中出血量多于对照组,独立负重时间短于对照组,术后并发症总发生率低于对照组(P<0.05)。术后,研究组Harris评分高于对照组(P<0.05)。结论骨水泥型加长柄髋关节置换结合股骨近端重建治疗老年不稳定性股骨转子间骨折的临床效果较股骨近端防旋髓内钉显著。     

Cementation of a Dual Mobility Cup Into an Existing Well-Fixed Metal Shell: A Reliable Option to Manage Wear-Related Recurrent Dislocation in Patients With High Surgical Risk

BackgroundDuring revision total hip arthroplasty (THA), the “double-socket” technique has been proposed as a straightforward solution in order to reduce the overall perioperative morbidity in patients with high surgical risk. However, the option of cementing a dual mobility cup into an existing well-fixed metal shell was sparsely reported. Therefore, this study aimed to evaluate the outcome of a “double-socket” technique performed with a cemented dual mobility cup in revision THA for late instability.MethodsTwenty-eight revision THAs (28 patients) were performed for wear-related recurrent dislocation using a “double-socket” technique with a cemented dual mobility cup and retrospectively reviewed. The age at revision averaged 82 years (range 74-93). According to the American Society of Anesthesiologists (ASA) physical status classification, 12 patients (43%) were ASA II and 16 patients (57%) were ASA III before revision.ResultsAt a mean follow-up of 3.5 years (range 2-5), the mean preoperative to postoperative functional outcome improved significantly (P < .01). The mean operative time was 107 minutes (range 75-140). The mean intraoperative bleeding was 200 mL (range 110-420). No postoperative complication, reoperation, or re-revision was reported. Importantly, no dislocation, dissociation of the cemented dual mobility cup construct, or aseptic loosening of the retained metal shell was observed.ConclusionThe “double-socket” technique with a dual mobility cup cemented into an existing well-fixed and well-positioned metal shell ensured a straightforward and blood-sparing revision technique that was efficient to restore stability and provide a secure acetabular construct in frail patients with high surgical risk and/or older than their natural life expectancy.     

Prosthesis displacement as a complication of reduction of a dislocated total hip arthroplasty

Acute displacement at the cement—prosthesis interface of the femoral component of a hip arthroplasty that occurred as a consequence of attempted reduction of a dislocation is described. Although this complication is theoretically possible with a polished tapered stem design, it is previously unrecognized, and may be avoidable if fluoroscopic control is used during closed reduction of a dislocation.     

Short vs Standard-Length Femoral Stems Cemented According to the “French Paradox”: A Matched Paired Prospective Study Using Ein Bild Roentgen Analyze Femoral Component at Two-Year Follow-Up

BackgroundThe purpose of this prospective matched paired study is to compare the in vivo migration patterns using Ein Bild Roentgen Analyze femoral component of shortened vs standard-length stems cemented line-to-line in primary total hip arthroplasty (THA) at 2-year follow-up.MethodsWe prospectively included the first 50 consecutive primary cemented THAs in 50 patients using a 12% shortened stem (AmisK group) of which design was derived from the original Charnley-Kerboull (CK) femoral components. These 50 patients were matched paired to 50 patients from a historical series of patients who underwent primary THAs using standard-length CK stems (CK group) with available long-term results, including Ein Bild Roentgen Analyze femoral component data at 2-year follow-up.ResultsBody mass index was significantly higher (P = .007) in the AmisK vs the CK group. At the 2-year follow-up, the mean subsidence was 0.65 mm (0-1.40) in the AmisK group vs 0.68 mm (0.07-1.43) in the CK group (P = .73). When using a 1.5-mm threshold, none of the stems in either group was considered to have subsided. Femoral cortical thickening in zones 3 and 5 occurred in 6 of the 50 hips (12%) in the AmisK group vs 20 (40%) of the 50 hips in the CK group (P = .003).ConclusionOur study showed that a shortened highly polished double-tapered stem cemented line-to-line provided similar results including minimal subsidence as its standard-length counterpart, with significantly less distal femoral cortical thickening. However, longer term survival analysis still needs to be determined.     

Are Cemented Endoprosthetic Reconstructions Superior to Uncemented Endoprostheses in Terms of Postoperative Outcomes and Complications in Patients with Extremity-Located Bone Metastasis Scheduled for Adjuvant Radiotherapy?

BackgroundAdjuvant radiotherapy frequently is used for prevention of recurrence following resection and endoprosthetic reconstruction of bone metastases. Besides this positive effect, radiotherapy can negatively affect both cemented and uncemented endoprostheses.MethodsWe retrospectively analyzed 130 extremities of 115 patients who underwent resection and cemented or uncemented endoprosthetic reconstruction for bone metastasis, followed by postoperative radiation therapy. The functional improvement was assessed by Karnofsky Performance Scale and Musculoskeletal Tumor Society (MSTS) scoring. The radiological evaluation mainly included analysis of “loosening areas” which were defined as the regions of osteolysis between the stem of the endoprostheses and the cement or cortex. The complications resulting in reconstruction failure and patient survival were recorded.ResultsA survival analysis revealed that 21 (18.3%) patients were alive with disease and 94 (81.7%) died of disease at the time of study. The mean last follow-up Karnofsky Performance Scale and MSTS scores of the whole study cohort were 78.69 ± 8.66 and 82.15 ± 9.06, respectively. There were 8 (6.15%) complications resulting in reconstruction failure, including aseptic loosening (2), femoral stem breakage (2), periprosthetic fracture (2), and infection (2). The number and time of complications did not show a significant difference between the cemented and uncemented groups (P > .05).ConclusionThis study demonstrated that there was no significant difference in complication rates of cemented or uncemented endoprosthetic reconstructions in patients with extremity-located bone metastases scheduled for adjuvant radiotherapy. The only result in favor of cemented prostheses was significantly higher MSTS functional scores at last follow-up.