We performed a retrospective review of a consecutive
series of 178 Mobility total ankle replacements (TARs) performed
by three surgeons between January 2004 and June 2009, and analysed
radiological parameters and clinical outcomes in a subgroup of 129
patients. The mean follow-up was 4 years (2 to 6.3). A total of
ten revision procedures (5.6%) were undertaken. The mean Ankle Osteoarthritis
Scale (AOS) pain score was 17 (0 to 88) and 86% of patients were
clinically improved at follow-up. However, 18 patients (18 TARs,
14%) had a poor outcome with an AOS pain score of >
30. A worse
outcome was associated with a pre-operative diagnosis of post-traumatic degenerative
arthritis. However, no pre- or post-operative radiological parameters
were significantly associated with a poor outcome. Of the patients
with persistent pain, eight had predominantly medial-sided pain.
Thirty TARs (29%) had a radiolucency in at least one zone. The outcome of the Mobility TAR at a mean of four years is satisfactory
in >
85% of patients. However, there is a significant incidence
of persistent pain, particularly on the medial side, for which we
were unable to establish a cause. Cite this article:
Mobile-bearing unicompartmental knee replacements
(UKRs) with a flat tibial plateau have not performed well in the
lateral compartment, owing to a high dislocation rate. This led
to the development of the Domed Lateral Oxford UKR (Domed OUKR)
with a biconcave bearing. The aim of this study was to assess the
survival and clinical outcomes of the Domed OUKR in a large patient
cohort in the medium term. We prospectively evaluated 265 consecutive knees with isolated
disease of the lateral compartment and a mean age at surgery of
64 years (32 to 90). At a mean follow-up of four years ( The Domed Lateral OUKR gives good clinical outcomes, low re-operation
and revision rates and a low dislocation rate in patients with isolated
lateral compartmental disease, in the hands of the designer surgeons. Cite this article:
Bone loss in the proximal tibia and distal femur
is frequently encountered in revision knee replacement surgery.
The various options for dealing with this depend on the extent of
any bone loss. We present our results with the use of cementless
metaphyseal metal sleeves in 103 patients (104 knees) with a mean
follow-up of 43 months (30 to 65). At final follow-up, sleeves in
102 knees had good osseointegration. Two tibial sleeves were revised
for loosening, possibly due to infection. The average pre-operative Oxford Knee Score was 23 (11 to 36)
and this improved to 32 (15 to 46) post-operatively. These early
results encourage us to continue with the technique and monitor
the outcomes in the long term. Cite this article:
We studied the bone mineral density (BMD) and
the bone mineral content (BMC) of the proximal tibia in patients with
a well-functioning uncemented Oxford medial compartment arthroplasty
using the Lunar iDXA bone densitometer. Our hypothesis was that
there would be decreased BMD and BMC adjacent to the tibial base
plate and increased BMD and BMC at the tip of the keel. There were 79 consecutive patients (33 men, 46 women) with a
mean age of 65 years (44 to 84) with a minimum two-year follow-up
(mean 2.6 years (2.0 to 5.0)) after unilateral arthroplasty, who
were scanned using a validated standard protocol where seven regions
of interest (ROI) were examined and compared with the contralateral
normal knee. All had well-functioning knees with a mean Oxford knee
score of 43 (14 to 48) and mean Knee Society function score of 90
(20 to 100), showing a correlation with the increasing scores and
higher BMC and BMD values in ROI 2 in the non-implanted knee relative
to the implanted knee (p = 0.013 and p = 0.015, respectively). The absolute and percentage changes in BMD and BMC were decreased
in all ROIs in the implanted knee compared with the non-implanted
knee, but this did not reach statistical significance. Bone loss
was markedly less than reported losses with total knee replacement. There was no significant association with side, although there
was a tendency for the BMC to decrease with age in men. The BMC
was less in the implanted side relative to the non-implanted side
in men compared with women in ROI 2 (p = 0.027), ROI 3 (p = 0.049)
and ROI 4 (p = 0.029). The uncemented Oxford medial compartment arthroplasty appears
to allow relative preservation of the BMC and BMD of the proximal
tibia, suggesting that the implant acts more physiologically than
total knee replacement. Peri-prosthetic bone loss is an important
factor in assessing long-term implant stability and survival, and
the results of this study are encouraging for the long-term outcome
of this arthroplasty. Cite this article:
Radiological assessment of total and unicompartmental
knee replacement remains an essential part of routine care and follow-up.
Appreciation of the various measurements that can be identified
radiologically is important. It is likely that routine plain radiographs
will continue to be used, although there has been a trend towards
using newer technologies such as CT, especially in a failing knee,
where it provides more detailed information, albeit with a higher
radiation exposure. The purpose of this paper is to outline the radiological parameters
used to evaluate knee replacements, describe how these are measured
or classified, and review the current literature to determine their
efficacy where possible.
Mechanical alignment has been a fundamental tenet of total knee arthroplasty (TKA) since modern knee replacement surgery was developed in the 1970s. The objective of mechanical alignment was to infer the greatest biomechanical advantage to the implant to prevent early loosening and failure. Over the last 40 years a great deal of innovation in TKA technology has been focusing on how to more accurately achieve mechanical alignment. Recently the concept of mechanical alignment has been challenged, and other alignment philosophies are being explored with the intention of trying to improve patient outcomes following TKA. This article examines the evolution of the mechanical alignment concept and whether there are any viable alternatives.
The use of robots in orthopaedic surgery is an
emerging field that is gaining momentum. It has the potential for significant
improvements in surgical planning, accuracy of component implantation
and patient safety. Advocates of robot-assisted systems describe
better patient outcomes through improved pre-operative planning
and enhanced execution of surgery. However, costs, limited availability,
a lack of evidence regarding the efficiency and safety of such systems
and an absence of long-term high-impact studies have restricted
the widespread implementation of these systems. We have reviewed
the literature on the efficacy, safety and current understanding of
the use of robotics in orthopaedics. Cite this article:
Component malalignment can be associated with
pain following total knee replacement (TKR). Using MRI, we reviewed
50 patients with painful TKRs and compared them with a group of
16 asymptomatic controls to determine the feasibility of using MRI
in evaluating the rotational alignment of the components. Using
the additional soft-tissue detail provided by this modality, we
also evaluated the extent of synovitis within these two groups.
Angular measurements were based on the femoral transepicondylar
axis and tibial tubercle. Between two observers, there was very
high interobserver agreement in the measurements of all values.
Patients with painful TKRs demonstrated statistically significant
relative internal rotation of the femoral component (p = 0.030).
There was relative internal rotation of the tibial to femoral component
and combined excessive internal rotation of the components in symptomatic
knees, although these results were significant only with one of
the observers (p = 0.031). There was a statistically significant
association between the presence and severity of synovitis and painful
TKR (p <
0.001). MRI is an effective modality in evaluating component rotational
alignment.
The objective of this study was to compare the early migration
characteristics and functional outcome of the Triathlon cemented
knee prosthesis with its predecessor, the Duracon cemented knee
prosthesis (both Stryker). A total 60 patients were prospectively randomised and tibial
component migration was measured by radiostereometric analysis (RSA)
at three months, one year and two years; clinical outcome was measured
by the American Knee Society score and the Knee Osteoarthritis and
Injury Outcome Score.Objectives
Methods
The Unified Classification System (UCS) was introduced
because of a growing need to have a standardised universal classification
system of periprosthetic fractures. It combines and simplifies many
existing classification systems, and can be applied to any fracture
around any partial or total joint replacement occurring during or
after operation. Our goal was to assess the inter- and intra-observer
reliability of the UCS in association with knee replacement when
classifying fractures affecting one or more of the femur, tibia
or patella. We used an international panel of ten orthopaedic surgeons with
subspecialty fellowship training and expertise in adult hip and
knee reconstruction (‘experts’) and ten residents of orthopaedic
surgery in the last two years of training (‘pre-experts’). They
each received 15 radiographs for evaluation. After six weeks they
evaluated the same radiographs again but in a different order. The reliability was assessed using the Kappa and weighted Kappa
values. The Kappa values for inter-observer reliability for the experts
and the pre-experts were 0.741 (95% confidence interval (CI) 0.707
to 0.774) and 0.765 (95% CI 0.733 to 0.797), respectively. The weighted
Kappa values for intra-observer reliability for the experts and
pre-experts were 0.898 (95% CI 0.846 to 0.950) and 0.878 (95% CI
0.815 to 0.942) respectively. The UCS has substantial inter-observer reliability and ‘near
perfect’ intra-observer reliability when used for periprosthetic
fractures in association with knee replacement in the hands of experienced
and inexperienced users. Cite this article:
The treatment of peri-prosthetic joint infection
(PJI) of the ankle is not standardised. It is not clear whether
an algorithm developed for hip and knee PJI can be used in the management
of PJI of the ankle. We evaluated the outcome, at two or more years
post-operatively, in 34 patients with PJI of the ankle, identified
from a cohort of 511 patients who had undergone total ankle replacement.
Their median age was 62.1 years (53.3 to 68.2), and 20 patients
were women. Infection was exogenous in 28 (82.4%) and haematogenous
in six (17.6%); 19 (55.9%) were acute infections and 15 (44.1%)
chronic. Staphylococci were the cause of 24 infections (70.6%).
Surgery with retention of one or both components was undertaken
in 21 patients (61.8%), both components were replaced in ten (29.4%),
and arthrodesis was undertaken in three (8.8%). An infection-free
outcome with satisfactory function of the ankle was obtained in
23 patients (67.6%). The best rate of cure followed the exchange
of both components (9/10, 90%). In the 21 patients in whom one or
both components were retained, four had a relapse of the same infecting organism
and three had an infection with another organism. Hence the rate
of cure was 66.7% (14 of 21). In these 21 patients, we compared
the treatment given to an algorithm developed for the treatment
of PJI of the knee and hip. In 17 (80.9%) patients, treatment was
not according to the algorithm. Most (11 of 17) had only one criterion against
retention of one or both components. In all, ten of 11 patients
with severe soft-tissue compromise as a single criterion had a relapse-free
survival. We propose that the treatment concept for PJI of the ankle
requires adaptation of the grading of quality of the soft tissues. Cite this article
Total knee replacement (TKR) smart tibial trials
have load-bearing sensors which will show quantitative compartment
pressure values and femoral-tibial tracking patterns. Without smart
trials, surgeons rely on feel and visual estimation of imbalance
to determine if the knee is optimally balanced. Corrective soft-tissue
releases are performed with minimal feedback as to what and how
much should be released. The smart tibial trials demonstrate graphically
where and how much imbalance is present, so that incremental releases
can be performed. The smart tibial trials now also incorporate accelerometers
which demonstrate the axial alignment. This now allows the surgeon
the option to perform a slight recut of the tibia or femur to provide
soft-tissue balance without performing soft-tissue releases. Using
a smart tibial trial to assist with soft-tissue releases or bone
re-cuts, improved patient outcomes have been demonstrated at one
year in a multicentre study of 135 patients (135 knees). Cite this article:
The aims of this retrospective study were to
compare the mid-term outcomes following revision total knee replacement
(TKR) in 76 patients (81 knees) <
55 years of age with those
of a matched group of primary TKRs based on age, BMI, gender and
comorbid conditions. We report the activity levels, functional scores,
rates of revision and complications. Compared with patients undergoing
primary TKR, those undergoing revision TKR had less improvement
in the mean Knee Society function scores (8.14 (–55 to +60) Young patients undergoing revision TKR should be counselled that
they can expect somewhat less improvement and a higher risk of complications
than occur after primary TKR. Cite this article:
Seven stiff total knee arthroplasties are presented
to illustrate the roles of: 1) manipulation under general anesthesia;
2) multiple concurrent diagnoses in addition to stiffness; 3) extra-articular
pathology; 4) pain as part of the stiffness triad (pain and limits
to flexion or extension); 5) component internal rotation; 6) multifactorial
etiology; and 7) surgical exposure in this challenging clinical
problem.
The Cementless Oxford Unicompartmental Knee Replacement
(OUKR) was developed to address problems related to cementation,
and has been demonstrated in a randomised study to have similar
clinical outcomes with fewer radiolucencies than observed with the
cemented device. However, before its widespread use it is necessary
to clarify contraindications and assess the complications. This
requires a larger study than any previously published. We present a prospective multicentre series of 1000 cementless
OUKRs in 881 patients at a minimum follow-up of one year. All patients
had radiological assessment aligned to the bone–implant interfaces
and clinical scores. Analysis was performed at a mean of 38.2 months
(19 to 88) following surgery. A total of 17 patients died (comprising
19 knees (1.9%)), none as a result of surgery; there were no tibial
or femoral loosenings. A total of 19 knees (1.9%) had significant
implant-related complications or required revision. Implant survival
at six years was 97.2%, and there was a partial radiolucency at
the bone–implant interface in 72 knees (8.9%), with no complete radiolucencies.
There was no significant increase in complication rate compared
with cemented fixation (p = 0.87), and no specific contraindications
to cementless fixation were identified. Cementless OUKR appears to be safe and reproducible in patients
with end-stage anteromedial osteoarthritis of the knee, with radiological
evidence of improved fixation compared with previous reports using
cemented fixation. Cite this article:
We report on the long-term results of 163 bicruciate-retaining
Hermes 2C total knee replacements in 130 patients at a mean follow-up
of 22.4 years (20.3 to 23.5). Even when the anterior cruciate ligament
had a partially degenerative appearance it was preserved as long
as the knee had a normal anterior drawer and Lachman’s test pre-operatively. The
description and surgical technique of this minimally constrained
prosthesis were published in 1983 and the ten-year clinical results
in 1999. A total of 12% of the knees (20 of 163) in this study were revised
because of wear of the polyethylene tibial insert. Excellent stability
was achieved and the incidence of aseptic component loosening was
4.3% (seven of 163). The survival rate using revision for any reason
as the endpoint was 82% (95% confidence interval 76.2 to 88.0). Although this series included a relatively small number of replacements,
it demonstrated that the anterior cruciate ligament, even when partially
degenerated at the time of TKR, remained functional and provided
adequate stability at a long-term follow-up. Cite this article:
We report the results of revision total knee
replacement (TKR) in 26 patients with major metaphyseal osteolytic defects
using 29 trabecular metal cones in conjunction with a rotating hinged
total knee prosthesis. The osteolytic defects were types II and
III (A or B) according to the Anderson Orthopaedic Research Institute
(AORI) classification. The mean age of the patients was 72 years
(62 to 84) and there were 15 men and 11 women. In this series patients had
undergone a mean of 2.34 previous total knee arthroplasties. The
main objective was to restore anatomy along with stability and function
of the knee joint to allow immediate full weight-bearing and active
knee movement. Outcomes were measured using Knee Society scores,
Oxford knee scores, range of movement of the knee and serial radiographs.
Patients were followed for a mean of 36 months (24 to 49). The mean
Oxford knee clinical scores improved from 12.83 (10 to 15) to 35.20
(32 to 38) (p <
0.001) and mean American Knee Society scores
improved from 33.24 (13 to 36) to 81.12 (78 to 86) (p <
0.001).
No radiolucent lines suggestive of loosening were seen around the trabecular
metal cones, and by one year all the radiographs showed good osteo-integration.
There was no evidence of any collapse or implant migration. Our
early results confirm the findings of others that trabecular metal
cones offer a useful way of managing severe bone loss in revision
TKR. Cite this article:
The February 2013 Knee Roundup360 looks at: mobile-bearing TKRs; arthroscopic ACL reconstruction; the use of chondrocytes for osteochondral defects; ACL reconstruction and the return to pivoting sports; ACLs and the MOON study; the benefit of knee navigation; and trabecular metal.