Aims

Patient dissatisfaction is not uncommon following primary total knee arthroplasty. One proposed method to alleviate this is by improving knee kinematics. Therefore, we aimed to answer the following research question: are there significant differences in knee kinematics based on the design of the tibial insert (cruciate-retaining (CR), ultra-congruent (UC), or medial congruent (MC))?

Aims

Current guidelines consider analyses of joint aspirates, including leucocyte cell count (LC) and polymorphonuclear percentage (PMN%) as a diagnostic mainstay of periprosthetic joint infection (PJI). It is unclear if these parameters are subject to a certain degree of variability over time. Therefore, the aim of this study was to evaluate the variation of LC and PMN% in patients with aseptic revision total knee arthroplasty (TKA).

Aims

To explore the clinical relevance of joint space width (JSW) narrowing on standardized-flexion (SF) radiographs in the assessment of cartilage degeneration in specific subregions seen on MRI sequences in knee osteoarthritis (OA) with neutral, valgus, and varus alignments, and potential planning of partial knee arthroplasty.

Aims

To compare patients undergoing total knee arthroplasty (TKA) with ≤ 80° range of movement (ROM) operated with a 2 mm increase in the flexion gap with matched non-stiff patients with at least 100° of preoperative ROM and balanced flexion and extension gaps.

Objectives

The monitoring of fracture healing is a complex process. Typically, successive radiographs are performed and an emerging calcification of the fracture area is evaluated. The aim of this study was to investigate whether different bone healing patterns can be distinguished using a telemetric instrumented femoral internal plate fixator.

We studied whether the presence of lateral osteophytes on plain radiographs was a predictor for the quality of cartilage in the lateral compartment of patients with varus osteoarthritic of the knee (Kellgren and Lawrence grade 2 to 3).

The baseline MRIs of 344 patients from the Osteoarthritis Initiative (OAI) who had varus osteoarthritis (OA) of the knee on hip-knee-ankle radiographs were reviewed. Patients were categorised using the Osteoarthritis Research Society International (OARSI) osteophyte grading system into 174 patients with grade 0 (no osteophytes), 128 grade 1 (mild osteophytes), 28 grade 2 (moderate osteophytes) and 14 grade 3 (severe osteophytes) in the lateral compartment (tibia). All patients had Kellgren and Lawrence grade 2 or 3 arthritis of the medial compartment. The thickness and volume of the lateral cartilage and the percentage of full-thickness cartilage defects in the lateral compartment was analysed.

There was no difference in the cartilage thickness or cartilage volume between knees with osteophyte grades 0 to 3. The percentage of full-thickness cartilage defects on the tibial side increased from < 2% for grade 0 and 1 to 10% for grade 3.

The lateral compartment cartilage volume and thickness is not influenced by the presence of lateral compartment osteophytes in patients with varus OA of the knee. Large lateral compartment osteophytes (grade 3) increase the likelihood of full-thickness cartilage defects in the lateral compartment.

Cite this article: Bone Joint J 2015;97-B:1634–9.

In an interdisciplinary project involving electronic engineers and clinicians, a telemetric system was developed to measure the bending load in a titanium internal femoral fixator. As this was a new device, the main question posed was: what clinically relevant information could be drawn from its application? As a first clinical investigation, 27 patients (24 men, three women) with a mean age of 38.4 years (19 to 66) with femoral nonunions were treated using the system. The mean duration of the nonunion was 15.4 months (5 to 69). The elasticity of the plate-callus system was measured telemetrically until union. Conventional radiographs and a CT scan at 12 weeks were performed routinely, and healing was staged according to the CT scans. All nonunions healed at a mean of 21.5 weeks (13 to 37). Well before any radiological signs of healing could be detected, a substantial decrease in elasticity was recorded. The relative elasticity decreased to 50% at a mean of 7.8 weeks (3.5 to 13) and to 10% at a mean of 19.3 weeks (4.5 to 37). At 12 weeks the mean relative elasticity was 28.1% (0% to 56%). The relative elasticity was significantly different between the different healing stages as determined by the CT scans.

Incorporating load measuring electronics into implants is a promising option for the assessment of bone healing. Future application might lead to a reduction in the need for exposure to ionising radiation to monitor fracture healing.

Purpose of the study: Implants with multidirectional locking screws theoretically have many advantages for the treatment of periprosthetic fractures. In the event of osteoporotic bone, this system of plate fixation ensures stability and better bone fixation. Using screws anchored in the different angles, we proposed rigid fixation around the prosthesis. We conducted a retrospective analysis of outcomes obtained after treatment of perprosthetic femoral fractures, Vancouver B1 and C, comparing two types of implants with angular stability (straight plate and folded plate).

Material and methods: From June 1999 to December 2007, we treated 58 patients with periprothetic fractures of the femur using locking plates. Mean age was 72.4 years, 40 patients were female. Thirty-two patients (55.2%) had a total hip prosthesis, 21 a total knee prosthesis and 5 both types of prosthesis (8.6%). We noted: peri- and postoperative complications, degree of bone healing, degree of mobility (Barthel Mobility index and stand up and go test) as well as the social status of the patients.

Results: Bone healing was obtained in 56 cases (96.5%). In two patients, the implant was dislocated and in four others there were general complications. The mean time necessary to obtain total weight-bearing two-leg stance was 8.6 weeks. Forty-six patients (78%) had the same social status as before the fracture. For mobility, 52 patients (89%) achieved the same level as before fracture. Four other patients required a crutch for walking and two needed a walker. Mean Barthel index was 85 points (max 100) and improved 35 points at onset of rehabilitation. Mean stand up and go was 22 s.

Conclusion: According to the review of the literature, 35% of plates dislocate after osteosynthesis of periprosthetic fractures. In our study, the rate was 3.5%, with 7% general complications. We can thus conclude that the methods presented here enable good bone healing in the majority of cases.

Implants with multidirectional locked screws have theoretical advantages in the treatment of periprosthetic fractures. In osteoporotic bone those locked plate systems with multidirectional applicable screws give a high stability. With the possibility of fixing screws in various angles, a rigid fixation in the presence of a prosthetic implant can be achieved. We concluded a retrospective study of a consecutive series of the outcome of Vancouver B1 and C femoral injuries using two specific locked implants (Straight and wave plate).

From June 1996 to December 2004 we treated 58 patients with a periprosthetic fracture of the femur with a locked plate. The mean age at the index procedure was 72.4 years, 40 patients were female (69%). In 32 cases (55.2%) we saw a hip endoprosthesis, in 21 cases (36.2%) a knee endoprosthesis and in 5 cases both (8.6%). Outcome measures were intra- and postoperative complications, bony union, degree of mobility and social status, Barthel mobility index and “stand up and go” test.

Union occurred in 56 cases (96.5%) after the index procedure. Twice the implant failed, we saw 4 general complications. The mean duration until full weight bearing status in these patients was 8.6 weeks.

At follow up 46 patients (78%) had maintained the same social status as before the fracture. Regarding the mobility status 52 patients (89%) had regained their previous level, 4 patients walking without aid before now required a cane and two patients a walking frame. The mean Barthel Index was 85 points of possible 100 and improved from 35 points at point of beginning of the rehabilitation. The mean stand-up& go time was measured as 22 seconds.

Conclusion: Overall failure rates of osteosynthesis after periprosthetic fractures of up to 35% are reported (20). With 3.5% implant related failures and 7% general complications, the presented Methods: achieve bony union and mobility in a high percentage of cases.

Introduction: Trauma surgeons are often less exposed to large caseloads of primary osteoarthritis, compared to purely “elective”orthopaedic surgeons. The experience in total knee arthroplasty is thereby markedly On the other hand, posttraumatic knee arthrosis is often accompanied by severe deformity and axis deviation. In theory, navigated arthroplasty can overcome some of the problems in this setting.

Aim: Evaluation of the navigated technique of total knee arthroplasty (TKA), including the technical difficulties, the learning curve and the feasibility in severe bony deformity. Setting is a level I trauma center. Study setup was prospective, follow up period on average 14.5 months (11–25 months).

Patients: Between 7/04–6/05 we treated 36 patients with arthritis of the knee related to trauma. 18 patients were male. Average age at TKA was 59 (32–77) years. On average patients had 2.83 previous operations.

Methods: The navigational system used is manufactured by PRAXIM (La Tronche/France). It uses infrared-tracking and bone-morphing software. The implant was a mobile bearing LCS knee (DePuy/USA). Follow up included radiographs, clinical examination and the knee society scores.

Results: In three cases the procedure was finished in a conventional technique, reasons were suspicion of the surgeon about the cuts recommended by the system, a missing femoral cut block and a broken screw of the tracker-fixation. There was no failure of the navigational system. There was a clear learning curve regarding procedure time. Preop mean extension deficit was improved from av. 7.1° (0–30°) to 1.67° (0°–10°) postop., flexion contracture improved from av. 95° to 103°. The combined knee society score (max. 200 pts) improved from 77 pts preop to 156 pts at follow up.

Conclusions: Navigated knee endoprosthesis is reliable tool for the trauma surgeon with few technical problems. Especially for surgeons with less experience in TKA, planning of implant size and position is very helpful. With posttraumatic deformity the surgeon can gain valuable information and assistance to improve alignment and ligamentous balancing.