Aims. The aim of this study was to investigate whether wear and backside deformation of polyethylene (PE) tibial inserts may influence the cement cover of tibial trays of explanted total knee arthroplasties (TKAs). Methods. At our retrieval centre, we measured changes in the wear and deformation of PE inserts using coordinate measuring machines and light microscopy. The amount of cement cover on the backside of tibial trays was quantified as a percentage of the total surface. The study involved data from the explanted fixed-bearing components of four widely used contemporary designs of TKA (Attune, NexGen, Press Fit Condylar (PFC), and Triathlon), revised for any indication, and we compared them with components that used previous generations of PE. Regression modelling was used to identify variables related to the amount of cement cover on the retrieved trays. Results. A total of 114 explanted fixed-bearing TKAs were examined. This included 76 used with contemporary PE inserts which were compared with 15 used with older generation PEs. The Attune and NexGen (central locking) trays were found to have significantly less cement cover than Triathlon and PFC trays (peripheral locking group) (p = 0.001). The median planicity values of the PE inserts used with central locking trays were significantly greater than of those with peripheral locking inserts (205 vs 85 microns; p < 0.001). Attune and NexGen inserts had a characteristic pattern of backside deformation, with the outer edges of the PE deviating inferiorly, leaving the PE margins as the primary areas of articulation. Conclusion. Explanted TKAs with central locking mechanisms were significantly more likely to debond from the cement mantle. The PE inserts of these designs showed characteristic patterns of deformation, which appeared to relate to the manufacturing process and may be exacerbated in vivo. This pattern of deformation was associated with PE wear occurring at the outer edges of the articulation, potentially increasing the frictional
Aims. Varus-valgus constrained (VVC) implants are often used during revision total knee arthroplasty (TKA) to gain coronal plane stability. However, the increased mechanical
We have compared the time to recovery of isokinetic
quadriceps strength after total knee replacement (TKR) using three
different lengths of incision in the quadriceps. We prospectively
randomised 60 patients into one of the three groups according to
the length of incision in the quadriceps above the upper border
of the patella (2 cm, 4 cm or 6 cm). The strength of the knees was
measured pre-operatively and every month post-operatively until
the peak quadriceps
Total knee arthroplasty (TKA) may provoke ankle symptoms. The aim of this study was to validate the impact of the preoperative mechanical tibiofemoral angle (mTFA), the talar tilt (TT) on ankle symptoms after TKA, and assess changes in the range of motion (ROM) of the subtalar joint, foot posture, and ankle laxity. Patients who underwent TKA from September 2020 to September 2021 were prospectively included. Inclusion criteria were primary end-stage osteoarthritis (Kellgren-Lawrence stage IV) of the knee. Exclusion criteria were missed follow-up visit, post-traumatic pathologies of the foot, and neurological disorders. Radiological angles measured included the mTFA, hindfoot alignment view angle, and TT. The Foot Function Index (FFI) score was assessed. Gait analyses were conducted to measure mediolateral changes of the gait line and ankle laxity was tested using an ankle arthrometer. All parameters were acquired one week pre- and three months postoperatively.Aims
Methods
Loosening of components after total knee arthroplasty (TKA) can be associated with the development of radiolucent lines (RLLs). The aim of this study was to assess the rate of formation of RLLs in the cemented original design of the ATTUNE TKA and their relationship to loosening. A systematic search was undertaken using the Cochrane methodology in three online databases: MEDLINE, Embase, and CINAHL. Studies were screened against predetermined criteria, and data were extracted. Available National Joint Registries in the Network of Orthopaedic Registries of Europe were also screened. A random effects model meta-analysis was undertaken.Aims
Methods
The aim of this study was to compare any differences in the primary outcome (biphasic flexion knee moment during gait) of robotic arm-assisted bi-unicompartmental knee arthroplasty (bi-UKA) with conventional mechanically aligned total knee arthroplasty (TKA) at one year post-surgery. A total of 76 patients (34 bi-UKA and 42 TKA patients) were analyzed in a prospective, single-centre, randomized controlled trial. Flat ground shod gait analysis was performed preoperatively and one year postoperatively. Knee flexion moment was calculated from motion capture markers and force plates. The same setup determined proprioception outcomes during a joint position sense test and one-leg standing. Surgery allocation, surgeon, and secondary outcomes were analyzed for prediction of the primary outcome from a binary regression model.Aims
Methods
The aim of this study was to compare the clinical outcomes of robotic arm-assisted bi-unicompartmental knee arthroplasty (bi-UKA) with conventional mechanically aligned total knee arthroplasty (TKA) during the first six weeks and at one year postoperatively. A per protocol analysis of 76 patients, 43 of whom underwent TKA and 34 of whom underwent bi-UKA, was performed from a prospective, single-centre, randomized controlled trial. Diaries kept by the patients recorded pain, function, and the use of analgesics daily throughout the first week and weekly between the second and sixth weeks. Patient-reported outcome measures (PROMs) were compared preoperatively, and at three months and one year postoperatively. Data were also compared longitudinally and a subgroup analysis was conducted, stratified by preoperative PROM status.Aims
Methods
The loss of full muscle activation contributes to weakness of the quadriceps muscle in patients with deficiency of the anterior cruciate ligament (ACL). We examined whether a deficit of voluntary activation (VA) of the quadriceps muscle can be reversed by reconstruction of the ACL and assessed its influence on muscle strength and clinical parameters. We evaluated 12 male subjects with an isolated tear of the ACL and 12 matched control subjects before operation and two years after reconstruction of the ACL. Assessment included measurements of isometric knee-extension
The removal of the cruciate ligaments in total knee arthroplasty (TKA) has been suggested as a potential contributing factor to patient dissatisfaction, due to alteration of the in vivo biomechanics of the knee. Bicruciate retaining (BCR) TKA allows the preservation of the cruciate ligaments, thus offering the potential to reproduce healthy kinematics. The aim of this study was to compare in vivo kinematics between the operated and contralateral knee in patients who have undergone TKA with a contemporary BCR design. A total of 29 patients who underwent unilateral BCR TKA were evaluated during single-leg deep lunges and sit-to-stand tests using a validated computer tomography and fluoroscopic imaging system. In vivo six-degrees of freedom (6DOF) kinematics were compared between the BCR TKA and the contralateral knee.Aims
Methods
The aim of this study was to determine whether closed suction drain (CSD) use influences recovery of quadriceps strength and to examine the effects of drain use on secondary outcomes: quadriceps activation, intra-articular effusion, bioelectrical measure of swelling, range of movement (ROM), pain, and wound healing complications. A total of 29 patients undergoing simultaneous bilateral total knee arthroplasty (TKA) were enrolled in a prospective, randomized blinded study. Patients were randomized to receive a CSD in one limb while the contralateral limb had the use of a subcutaneous drain (SCDRN) without the use of suction (‘sham drain’). Isometric quadriceps strength was collected as the primary outcome. Secondary outcomes consisted of quadriceps activation, intra-articular effusion measured via ultrasound, lower limb swelling measured with bioelectrical impendence and limb girth, knee ROM, and pain. Outcomes were assessed preoperatively and postoperatively at day two, two and six weeks, and three months. Differences between limbs were determined using paired Student’s Aims
Patients and Methods
Our aim was to compare kinematic with mechanical alignment in
total knee arthroplasty (TKA). We performed a prospective blinded randomised controlled trial
to compare the functional outcome of patients undergoing TKA in
mechanical alignment (MA) with those in kinematic alignment (KA).
A total of 71 patients undergoing TKA were randomised to either
kinematic (n = 36) or mechanical alignment (n = 35). Pre- and post-operative
hip-knee-ankle radiographs were analysed. The knee injury and osteoarthritis
outcome score (KOOS), American Knee Society Score, Short Form-36,
Euro-Qol (EQ-5D), range of movement (ROM), two minute walk, and timed
up and go tests were assessed pre-operatively and at six weeks,
three and six months and one year post-operatively.Aims
Patients and Methods
The aim of this study was to evaluate the long-term inducible
displacement of cemented tibial components ten years after total
knee arthroplasty (TKA). A total of 15 patients from a previously reported prospective
trial of fixation using radiostereometric analysis (RSA) were examined
at a mean of 11 years (10 to 11) postoperatively. Longitudinal supine
RSA examinations were acquired at one week, one year, and two years
postoperatively and at final follow-up. Weight-bearing RSA examinations
were also undertaken with the operated lower limb in neutral and
in maximum internal rotation positions. Maximum total point motion
(MTPM) was calculated for the longitudinal and inducible displacement examinations
(supine Aims
Patients and Methods
The aim of this study was to compare the outcome of revision
total knee arthroplasty (TKA) with and without proximalisation of
the tibial tubercle in patients with a failed primary TKA who have
pseudo patella baja. All revision TKAs, performed between January 2008 and November
2013 at a tertiary referral University Orthopaedic Department were
retrospectively reviewed. Pseudo patella baja was defined using
the modified Insall-Salvati and the Blackburne-Peel ratios. A proximalisation
of the tibial tubercle was performed in 13 patients with pseudo
patella baja who were matched with a control group of 13 patients
for gender, age, height, weight, body mass index, length of surgery
and Blackburne-Peel ratio. Outcome was assessed two years post-operatively
using the Knee Society Score (KSS).Aims
Patients and Methods
To assess the effect of high tibial and distal femoral osteotomies
(HTO and DFO) on the pressure characteristics of the ankle joint. Varus and valgus malalignment of the knee was simulated in human
cadaver full-length legs. Testing included four measurements: baseline
malalignment, 5° and 10° re-aligning osteotomy, and control baseline
malalignment. For HTO, testing was rerun with the subtalar joint
fixed. In order to represent half body weight, a 300 N force was applied
onto the femoral head. Intra-articular sensors captured ankle pressure.Aims
Materials and Methods
There have been differing descriptions of the
anterolateral structures of the knee, and not all have been named
or described clearly. The aim of this study was to provide a clear
anatomical interpretation of these structures. We dissected 40 fresh-frozen
cadaveric knees to view the relevant anatomy and identified a consistent
structure in 33 knees (83%); we termed this the anterolateral ligament
of the knee. This structure passes antero-distally from an attachment
proximal and posterior to the lateral femoral epicondyle to the
margin of the lateral tibial plateau, approximately midway between
Gerdy’s tubercle and the head of the fibula. The ligament is superficial
to the lateral (fibular) collateral ligament proximally, from which
it is distinct, and separate from the capsule of the knee. In the
eight knees in which it was measured, we observed that the ligament
was isometric from 0° to 60° of flexion of the knee, then slackened
when the knee flexed further to 90° and was lengthened by imposing
tibial internal rotation. Cite this article:
The clinical diagnosis of a partial tear of the
anterior cruciate ligament (ACL) is still subject to debate. Little
is known about the contribution of each ACL bundle during the Lachman
test. We investigated this using six fresh-frozen cadaveric lower
limbs. Screws were placed in the femora and tibiae as fixed landmarks
for digitisation of the bone positions. The femur was secured horizontally
in a clamp. A metal hook was screwed to the tibial tubercle and
used to apply a load of 150 N directed anteroposteriorly to the
tibia to simulate the Lachman test. The knees then received constant
axial compression and 3D knee kinematic data were collected by digitising
the screw head positions in 30° flexion under each test condition.
Measurements of tibial translation and rotation were made, first with
the ACL intact, then after sequential cutting of the ACL bundles,
and finally after complete division of the ACL. Two-way analysis
of variance analysis was performed. During the Lachman test, in all knees and in all test conditions,
lateral tibial translation exceeded that on the medial side. With
an intact ACL, both anterior and lateral tibial landmarks translated
significantly more than those on the medial side (p <
0.001).
With sequential division of the ACL bundles, selective cutting of
the posterolateral bundle (PLB) did not increase translation of
any landmark compared with when the ACL remained intact. Cutting the
anteromedial bundle (AMB) resulted in an increased anterior translation
of all landmarks. Compared to the intact ACL, when the ACL was fully
transected a significant increase in anterior translation of all
landmarks occurred (p <
0.001). However, anterior tibial translation
was almost identical after AMB or complete ACL division. We found that the AMB confers its most significant contribution
to tibial translation during the Lachman test, whereas the PLB has
a negligible effect on anterior translation. Section of the PLB
had a greater effect on increasing the internal rotation of the
tibia than the AMB. However, its contribution of a mean of 2.8°
amplitude remains low. The clinical relevance of our investigation
suggests that, based on anterior tibial translation only, one cannot distinguish
between a full ACL and an isolated AMB tear. Isolated PLB tears
cannot be detected solely by the Lachman test, as this bundle probably
contributes more resistance to the pivot shift.
We assessed the functional outcome following fracture of the tibial plateau in 63 consecutive patients. Fifty-one patients were treated by internal fixation, five by combined internal and external fixation and seven non-operatively. Measurements of joint movement and muscle function were made using a muscle dynamometer at three, six and 12 months following injury. Thirteen patients (21%) had a residual flexion contracture at one year. Only nine (14%) patients achieved normal quadriceps muscle strength at 12 months, while 19 (30%) achieved normal hamstring muscle strength. Recovery was significantly slower in patients older than 40 years of age. We conclude that there is significant impairment of movement and muscle function after fracture of the tibial plateau and that the majority of patients have not fully recovered one year after injury.
We have investigated the changes in anterior laxity of the knee in response to direct electrical stimulation of eight normal and 45 reconstructed anterior cruciate ligaments (ACLs). In the latter, the mean time from reconstruction was 26.7 months (24 to 32). The ACL was stimulated electrically using a bipolar electrode probe during arthroscopy. Anterior laxity was examined with the knee flexed at 20° under a force of 134 N applied anteriorly to the tibia using the KT-2000 knee arthrometer before, during and after electrical stimulation. Anterior tibial translation in eight normal and 17 ACL-reconstructed knees was significantly decreased during stimulation, compared with that before stimulation. In 28 knees with reconstruction of the ACL, in 22 of which the grafts were found to have detectable somatosensory evoked potentials during stimulation, anterior tibial translation was not decreased. These findings suggest that the ACL-hamstring reflex arc in normal knees may contribute to the functional stability and that this may not be fully restored after some reconstructions of the ACL.
We have developed a new tensor for total knee replacements which is designed to assist with soft-tissue balancing throughout the full range of movement with a reduced patellofemoral joint. Using this tensor in 40 patients with osteoarthritis we compared the intra-operative joint gap in cruciate-retaining and posterior-stabilised total knee replacements at 0°, 10°, 45°, 90° and 135° of flexion, with the patella both everted and reduced. While the measurement of the joint gap with a reduced patella in posterior-stabilised knees increased from extension to flexion, it remained constant for cruciate-retaining joints throughout a full range of movement. The joint gaps at deep knee flexion were significantly smaller for both types of prosthetic knee when the patellofemoral joint was reduced (p <
0.05).
Between 2003 and 2007, 99 knees in 77 patients
underwent opening wedge high tibial osteotomy. We evaluated the effect
of initial stable fixation combined with an artificial bone substitute
on the mid- to long-term outcome after medial opening-wedge high
tibial osteotomy (HTO) for medial compartmental osteoarthritis or
spontaneous osteonecrosis of the knee in 78 knees in 64 patients
available for review at a minimum of five years (mean age 68 years;
49 to 82). The mean follow-up was 6.5 years (5 to 10). The mean
Knee Society knee score and function score improved from 49.6 ( Opening-wedge HTO using a stable plate fixation system combined
with a bone substitute is a reliable procedure that provides excellent
results. Although this treatment might seem challenging for older
patients, our results strongly suggest that the results are equally
good. Cite this article: