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))? Overall, 15 cadaveric knee joints were examined with a CR implant with three different tibial inserts (CR, UC, and MC) using an established knee joint simulator. The effects on coronal alignment, medial and lateral femoral roll back, femorotibial rotation, bony rotations (femur, tibia, and patella), and patellofemoral length ratios were determined.Aims
Methods
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). We conducted a prospective, double-centre study of 40 patients with 40 knee joints. Patients underwent joint aspiration at two different time points with a maximum period of 120 days in between these interventions and without any events such as other joint aspirations or surgeries. The main indications for TKA revision surgery were aseptic implant loosening (n = 24) and joint instability (n = 11).Aims
Methods
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. We retrospectively reviewed 639 subjects, aged 45 to 79 years, in the Osteoarthritis Initiative (OAI) study, who had symptomatic knees with Kellgren and Lawrence grade 2 to 4. Knees were categorized as neutral, valgus, and varus knees by measuring hip-knee-angles on hip-knee-ankle radiographs. Femorotibial JSW was measured on posteroanterior SF radiographs using a special software. The femorotibial compartment was divided into 16 subregions, and MR-tomographic measurements of cartilage volume, thickness, and subchondral bone area were documented. Linear regression with adjustment for age, sex, body mass index, and Kellgren and Lawrence grade was used.Aims
Methods
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. In a retrospective cohort study, 98 TKAs (91 patients) with a preoperative ROM of ≤ 80° were examined. Mean follow-up time was 53 months (24 to 112). All TKAs in stiff knees were performed with a 2 mm increased flexion gap. Data were compared to a matched control group of 98 TKAs (86 patients) with a mean follow-up of 43 months (24 to 89). Knees in the control group had a preoperative ROM of at least 100° and balanced flexion and extension gaps. In all stiff and non-stiff knees posterior stabilized (PS) TKAs with patellar resurfacing in combination with adequate soft tissue balancing were used.Aims
Methods
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. An electronic telemetric system was developed to assess bone healing mechanically. The system consists of a telemetry module which is applied to an internal locking plate fixator, an external reader device, a sensor for measuring externally applied load and a laptop computer with processing software. By correlation between externally applied load and load measured in the implant, the elasticity of the osteosynthesis is calculated. The elasticity decreases with ongoing consolidation of a fracture or nonunion and is an appropriate parameter for the course of bone healing. At our centre, clinical application has been performed in 56 patients suffering nonunion or fracture of the femur.Objectives
Materials and Methods
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:
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.
