Treatment of periprosthetic knee infection and coexistent periprosthetic fracture:A case report and literature review

BACKGROUND Periprosthetic joint infection(PJI) and periprosthetic fracture(PPF) are among the most serious complications following total knee arthroplasty. Herein, we present one patient with these two complications with details on the characteristics, treatment strategy, and outcome.CASE SUMMARY A 69-year-old female patient who suffered from PJI and PPF following total knee arthroplasty was treated by a two-stage revision surgery. After thorough foreign material removal and debridement, we used a plate that was covered with antibiotic-loaded bone cement to link with a hand-made cement spacer to occupy the joint space and fix the fracture. Although the infection was cured, the fracture did not heal and caused bone defect due to the long interval between debridement and revision. In the revision surgery, a cemented stem and cortical allogenic splints were used to reconstruct the fracture and bone defect. At the final followup 27 mo after revision, the patient was satisfied with postoperative knee functions with satisfactory range of motion(104°) and Hospital for Special Surgery knee score(82 points). The radiographs showed no loosening of the prosthesis and that the bone grafts healed well with the femur.CONCLUSION Our two-stage revision surgery has proved to be successful and may be considered in other patients with PJI and PPF.

Modified fixation for periprosthetic supracondylar femur fractures:Two case reports and review of the literature

BACKGROUND Periprosthetic supracondylar femoral fractures(PSFs)present a challenge in terms of optimizing fixation in patients with poor bone quality.Surgical treatment and peri-operative management of PSFs in the elderly remain a burden for orthopedic surgeons.Among different treatment options,locking plate(LP)and retrograde intramedullary nail(RIMN)have shown favorable results.However,reduced mobility and protected weight-bearing are often present in the postoperative older population.With a purpose of allowing for early weight-bearing,a modified nail plate combination(NPC)was redesigned for PSF management.CASE SUMMARY In our cases,two elderly osteoporotic female underwent total knee arthroplasty(TKA),and then suffered from low energy trauma onto their knees after falling to the floor.Plain radiographs or computed tomography scans demonstrated oblique or transverse PSFs,both of which occurred at the distal femur above TKA.The modified NPC technique was performed for treatment of PSFs.The patient was made foot flat weight bearing in 1 wk.At 6-mo follow-up,the union was ultimately achieved using modified NPC with satisfactory implant outcomes.CONCLUSION Neither LP nor RIMN alone may provide adequate support to allow for union in circumstances where the patient has severely osteopenic bone.Therefore,developing a modified implant offer an alternative choice for treating PSFs.These two cases revealed that this technique is a viable option for the geriatric osteoporotic PSFs,offering safe,early weight bearing and favorable clinical outcomes.

Prediction of Intraoperative Fracture by Hammering Sound Frequency Analysis and Stress Estimation during Total Hip Arthroplasty

When a stem is inserted into the femur during total hip arthroplasty, sufficient fixation depends on the surgeon’s experience. An objective method of evaluating whether the stem has been correctly fixed may aid clinicians in their decision. We examined the relationship between the sound frequency caused by hammering the stem and the internal stress in artificial femurs, and evaluated the utility of sound frequency analysis to prevent intraoperative fracture. Surgeons inserted one of two types of cementless stems (SL-PLUS and modified CLS) using routine operational procedures into 13 artificial femurs. These are the standard Zweymüllers used in Europe. The difference is the lateral shape;SL-PLUS has holes for removal and the modified CLS has fins to prevent rotation. We estimated stress in the femur via finite element analysis, measured the hammering force, and recorded the sound of hammering for frequency analysis. Finite element analysis revealed that the hammering sound frequency decreased as the maximum stress increased. A decrease in frequency suggested that fixation was sufficient and that continued hammering would increase the risk of fracture. Thus, evaluation of the change in sound frequency during stem insertion may indicate when the hammering force should be reduced, thereby preventing intraoperative periprosthetic fractures. Further frequency change may also predict fractures prior to visual confirmation. We concluded that sound frequency analysis has potential as an objective evaluation method to help prevent intraoperative periprosthetic fractures during stem insertion.

Investigation of Hammering Sound Frequency to Prevent Intraoperative Fracture during Total Hip Arthroplasty

Background: The 1st peak frequency of the hammering sound in total hip arthroplasty may serve as an evaluation index to prevent intraoperative fracture. Fixation of the stem and femur cannot be acquired unless the 1st peak frequency of hammering the stem into the femur stabilizes, and fixation can be judged as acquired when the 1st peak frequency becomes constant. To investigate whether the environmental sound in the operating room can be differentiated from the hammering sound of total hip arthroplasty, the 1st peak frequency of the hammering sound when impacting the stem into the femur with a hammer was identified. Method: The hammering sound of impacting the stem into a biomechanical test material through an impactor was analyzed using a fast Fourier transform analyzer. Environmental sound in the operating room was simulated and the 1st peak frequency of the sound on collision between the operator’s voice and the surgical instrument was measured. The 1st peak frequency of hammering sound was compared between patients indicated for total hip arthroplasty and healthy individuals to investigate whether there is a difference due to bone quality. Results: The natural frequency of the impactor was 3.41 ± 0.05 kHz, and the 1st peak frequency of the femur, stem, and impactor was 2.43 ± 1.45 kHz. The 1st peak frequency of hammering sound on simulated femur in patients indicated for total hip arthroplasty was 2.98 ± 0.73 kHz and that in healthy individuals was 2.15 ± 0.32 kHz. This suggested that the hammering sound in total hip arthroplasty-indicated patients overlaps with the frequency of the collision sound of surgical instruments. Conclusion: To develop a system to prevent intraoperative fracture, countermeasures, such as noise canceling, are necessary to prevent false detection of hammering sounds.

Ankle Arthrodesis Nail Combined with Locking Compression Plate to Stabilize Two-Level Pathologic Tibial Fractures

Treatment of fragility fractures of the distal tibia in the elderly is demanding because of osteopenic bone quality, the delicate soft tissue cuff and frequent critical circulation. We report the case of two-level tibial pseudarthroses in an 83- year-old woman caused by multiple myeloma successfully stabilized by a long ankle arthrodesis nail combined with locking compression plate osteosynthesis. This case is unique, as to our best knowledge, herein diaphyseal fractures were treated for the first time using a technique reported hitherto primarily for fragility ankle and pilon fractures.

一位98岁高龄男性接受假体周围骨折手术的麻醉思路（英文）

A 98-year-old male patient with history of hemiarthroplasty suffered periprosthetic fracture of right femoral shaft and developed acute coronary event in three days after hospitalization.Femoral nerve and lateral femoral cutaneous nerve blocks combined with general anesthesia were implemented for the internal fixation surgery.The recovery was uneventful after discharge.In this case report,we discussed the main considerations of anesthesia specifically for this complicated case.

Combined use of extensively porous coated femoral components with onlay cortical strut allografts in revision of Vancouver B2 and B3 periprosthetic femoral fractures

Background Periprosthetic femoral fractures following total hip arthroplasty are getting more prevalent. The aim of this study was to evaluate the clinical results of combined use of uncemented extensively porous coated femoral components with onlay cortical strut allografts in revision of Vancouver type B2 and B3 periprosthetic femoral fractures. Methods Thirteen hips after total hip arthroplasty in 13 patients who suffered a Vancouver B2 or B3 periprosthetic fracture were treated with an uncemented extensively porous coated femoral component combined with onlay cortical strut allografts. Each patient was assigned a Harris hip score, and a visual analog scale （VAS） score for pain and satisfaction. Radiographs were examined for component stability, fracture site and allograft-host union and allograft reconstruction. Results At an average of 5.3-year follow-up, no patient required repeat revision. The average Harris hip score was （71.8±6.3） points, the pain VAS score was （16.6±4.3） points, and the patient satisfaction VAS score was （81.5±5.7） points Radiographic examination showed no detectable loosening of the prostheses, and 12 cases were presented fixation by osseointegration and the other one was stable fibrous ingrown fixation. All fractures united for （5.2±1.4） months in average. And all onlay strut allografts united to host bone for about （11.5±2.6） months. Conclusions Combined use of uncemented, long stemmed, extensively porous coated implant with cortical onlay strut allografts can achieve good clinic results and high rate of union for both fracture site and allograft-host bone junction. This technique could be used routinely to augment fixation and healing of Vancouver B2 and B3 periprosthetic fractures.