Total knee replacement (TKR) design aims to restore normal kinematics with emphasis on flexion range. The survivorship of a TKR is dependent on the kinematics in six-degrees-of-freedom (6-DoF). Stepping up, such as stair ascent is a kinematically demanding activity after TKR. The debate about design choice has not yet been informed by 6-DoF in vivo kinematics. This prospective randomised controlled trial (RCT) compared kneeling kinematics in three TKR designs.

68 participants were randomised to receive either cruciate retaining (CR-FB), rotating platform (CR-RP) or posterior stabilised (PS-FB) prostheses. Image quality was sufficient for 49 of these patients to be included in the final analysis following a minimum 1-year follow-up. Patients completed a step-up task while being imaged using single-plane fluoroscopy. Femoral and tibial computer-aided design (CAD) models for each of the TKR designs were registered to the fluoroscopic images using bespoke software OrthoVis to generate six-degree-of-freedom kinematics. Differences in kinematics between designs were compared as a function of flexion.

There were no differences in terminal extension between the groups. The CR-FB was further posterior and the CR-RP was more externally rotated at terminal extension compared to the other designs. Furthermore, the CR-FB designs was more posteriorly positioned at each flexion angle compared to both other designs. Additionally, the CR-RP design had more external femoral rotation throughout flexion when compared with both fixed bearing designs. However, there were no differences in total rotation for either step-up or down. Visually, it appears there was substantial variability between participants in each group, indicating unique patient-specific movement patterns.

While use of a specific implant design does influence some kinematic parameters, the overall patterns are similar. Furthermore, there is high variability indicating patient-specific kinematic patterns. At a group level, none of these designs appear to provide markedly different step-up kinematic patterns. This is important for patient expectations following surgery. Future work should aim to better understand the unique patient variability.

Summary Statement

Using the latest Next Generation Sequencing technologies, we have investigated miRNA expression profiles in human trabecular bone from total hip replacement (THR) revision surgery where wear particle associated osteolysis was evident.

Thoracic kyphosis increases with age. The resultant increase in compression forces on the anterior vertebral bodies leads to further kyphotic deformity and, an increased likelihood of vertebral collapse. This study aimed to determine the relative efficacy of two therapeutic strategies commonly used to treat hyperkyphosis.

69 subjects (26 male: 43 female) were randomised into 4 groups: strengthening, postural re-education (PEd), both and control. The strengthening group attended a gym 3 times a week for 12 weeks to perform seated extension exercises. The PEd group had 3 physiotherapy sessions within a 12 week period in which they received postural assessment and a home exercise programme. The combined group received both interventions while the control group received neither. Outcome measurements were assessed at baseline and 12 weeks. They included static (inclinometer) and 6-hour angular measurements (using flexible electrogoniometer (FEG)) and physical function tests.

There were no significant differences between the marginal means of the angular measurements for any of the intervention groups. However, the group which received both interventions demonstrated reduced kyphosis as measured by the FEG angles (apex of the curve between T3 and T11), while the strengthening group showed reduced inclinometer angles (between T1 and T12). The strengthening group showed improvement in back extensor strength (BES) (0.6 +/− 0.2 N/kg, p < 0.01), time to walk 10 metres (−0.3 +/− 0.6 s, p < 0.05), and time to stand and sit 5 times (−0.9 +/− 0.6 s, p < 0.05). However, there was no relationship between change in BES and change in kyphotic angle. The PEd group showed the greatest improvement in the timed up and go test but this was not significant. Improvement in inclinometer angle over the 12 weeks was associated with degree of kyphosis at baseline (upright inclinometer r = −0.47, p=0.0001) but this relationship was not apparent in the FEG measurements. Both the FEG and inclinometer angles showed a marked decrease in degree of improvement in subjects aged >70.

(50/50). A combination of strengthening and PEd was most effective at reducing hyperkyphosis. BES was improved with resisted strengthening but not with home-based postural exercises. However, increased BES was not associated with decreased kyphosis. Larger baseline kyphosis was associated with greater angular improvement. Subjects aged >70 were less likely to improve.

The Biometrics Flexible Electrogoniometer (FEG) is a lightweight device which when attached over joints can record angular displacements for periods of up to 10 hours.

The aim of this study was to examine the validity of the FEG for measuring the thoracic spine using the Cobb angle and functional activities.

12 subjects (6 F, 71±11years; 6 M, 65±11) were X-rayed in upright and “slumped” standing with the FEG attached to their thoracic spine. Three Cobb angles were obtained from the vertebrae underlying the FEG at the outer margins (OEB); the inner margins (IEB), and the mid points (MEB), of the FEG end blocks.

Comparisons of FEG and Cobb angles were derived with intraclass correlation coefficients (ICC).

In a separate experiment, 12 subjects (8F, 43±13; 4M, 35±17) performed 7 functional activities one week apart in order to assess day-to-day reliability of the FEG. Time 1 and time 2 angles were compared with an ICC.

The mean FEG angles for upright and “slumped standing” were 31±7° and 39±8° (mean ± SD) respectively. The corresponding mean OEB Cobb angles were 48±13° and 52±12°; the mean IEB Cobb angles were 24±11° and 29±10°; and the MEB Cobb angles were 36±13° and 41±10°.

The correlation between the FEG and OEB Cobb was ICC(2,1)=0.85; between FEG and IEB Cobb was ICC(2,1)=0.77 and between FEG and MEB Cobb was ICC(2,1)=0.87.

The second experiment compared day-to day reliability of the FEG when used over the thoracic spine. For the 7 activities performed: standing erect, standing slumped, reaching up, reaching down, and walking on-the-spot, the mean correlation between the measures on day 1 and day 2 was ICC(2,1)=0.96 (range 0.94 to 0.98).

This study has shown that the FEG demonstrates excellent internal and external validity in the thoracic spine. Further, it has demonstrated that the FEG measures the segment of the spine between the mid-endblocks. Future studies are planned which will use the FEG to evaluate interventions aimed at treating thoracic kyphosis

Intramedullary reaming causes elevation in intramedullary pressure (IP) and extravasation of intramedullary contents into the venous blood system. This study was to evaluate the effect of an intramedullary suction system (ISS), recently developed in our laboratory, on the IP and fat extravasation in a sheep model.

Twelve skeletal mature sheep were assigned randomly to 2 experimental groups of 6 sheep: instrumentation and reamed intramedullary nailing without the ISS application and instrumentation and reamed intramedullary nailing with ISS application. During reaming, the IP was recorded at each step of the procedure. Haemo-dynamic parameters were monitored at pre-reaming, 10 min post-reaming, and 50 min post-reaming, including, mean arterial blood pressure (MABP), pulmonary artery pressure (PAP), pulmonary arterial CO2 (Paco2), heart rate (HR), and saturated oxygen (SaO2). Blood and lung tissue samples were collected for the examination of medullary fat intravasations.

Dramatic increases in IP were observed in non-ISS group at the six defined measuring times: before drilling, guide wire, reaming 8 mm (reamer size), 9 mm, reaming 10 mm, and reaming 11 mm. The IP during reaming was significantly lower in ISS group (guide wire, 15 mmHg; 8 mm, 13 mmHg; 9 mm, -1 mmHg; 10 mm, 3 mmHg; 11 mm, 16 mmHg) than in non-ISS group (guide wire, 28, 8 mm, 185 mmHg; 9 mm, 168 mmHg; 10 mm, 146 mmHg; 11 mm, 150 mmHg). These reductions were significant with the P values < 0.05 or 0.01. Paco2, was lower in ISS group than non-ISS group (32 and 40 mmHg, respectively), while SaO2 was higher in ISS group than non-ISS group (99 and 91 mmHg, respectively). Histological data revealed fat emboli in sheep lung tissue in non-ISS group. Total lipids in lung specimen was lower in ISS group (7.6 mg/g tissue) than in non-ISS group (13.6 mg/g, P=0.04).

We demonstrate the ISS in controlling the increase in IP occurring in long bone reaming. The ISS allows real time pressure recording and feedback to the operator. With this feedback, the operating surgeon is able to control the rate of forward reaming to prevent major increases in IP