Periprosthetic fracture (PF) after primary total hip arthroplasty
(THA) is an uncommon but potentially devastating complication. This
study aims to investigate the influence of cemented stem designs
on the risk of needing a revision for a PF. We analysed data on 257 202 primary THAs with cemented stems
and 390 linked first revisions for PF recorded in the National Joint
Registry (NJR) of England, Wales and Northern Ireland to determine
if a cemented femoral stem brand was associated with the risk of
having revision for a PF after primary THA. All cemented femoral
stem brands with more than 10 000 primary operations recorded in
the NJR were identified. The four most commonly used cemented femoral
stems were the Exeter V40 (n = 146 409), CPT (n = 24 300), C-Stem
(n = 15 113) and Charnley (n = 20 182). We compared the revision risk ratios due to PF amongst the stems
using a Poisson regression model adjusting for patient factors.
Compared with the Exeter V40, the age, gender and ASA grade adjusted
revision rate ratio was 3.89 for the cemented CPT stem (95% confidence
interval (CI) 3.07 to 4.93), 0.89 for the C-Stem (95% CI 0.57 to
1.41) and 0.41 for the Charnley stem (95% CI 0.24 to 0.70).Aims
Patients and Methods
Inherent disadvantages of reverse shoulder arthroplasty
designs based on the Grammont concept have raised a renewed interest
in less-medialised designs and techniques. The aim of this study
was to evaluate the outcome of reverse shoulder arthroplasty (RSA)
with the fully-constrained, less-medialised, Bayley–Walker prosthesis performed
for the treatment of rotator-cuff-deficient shoulders with glenohumeral
arthritis. A total of 97 arthroplasties in 92 patients (53 women
and 44 men, mean age 67 years (standard deviation ( The Bayley–Walker prosthesis provides reliable pain relief and
reasonable functional improvement for patients with symptomatic
cuff-deficient shoulders. Compared with other designs of RSA, it
offers a modest improvement in forward elevation, but restores external
rotation to some extent and prevents scapular notching. A longer
follow-up is required to assess the survival of the prosthesis and
the clinical performance over time. Cite this article:
There are three basic concepts that are important to the biomechanics of pedicle screw-based instrumentation. First, the outer diameter of the screw determines pullout strength, while the inner diameter determines fatigue strength. Secondly, when inserting a pedicle screw, the dorsal cortex of the spine should not be violated and the screws on each side should converge and be of good length. Thirdly, fixation can be augmented in cases of severe osteoporosis or revision. A trajectory parallel or caudal to the superior endplate can minimise breakage of the screw from repeated axial loading. Straight insertion of the pedicle screw in the mid-sagittal plane provides the strongest stability. Rotational stability can be improved by adding transverse connectors. The indications for their use include anterior column instability, and the correction of rotational deformity.
The aim of this study was to quantify the stability
of fracture-implant complex in fractures after fixation. A total
of 15 patients with an undisplaced fracture of the femoral neck,
treated with either a dynamic hip screw or three cannulated hip
screws, and 16 patients with an AO31-A2 trochanteric fracture treated
with a dynamic hip screw or a Gamma Nail, were included. Radiostereometric
analysis was used at six weeks, four months and 12 months post-operatively
to evaluate shortening and rotation. Migration could be assessed in ten patients with a fracture of
the femoral neck and seven with a trochanteric fracture. By four
months post-operatively, a mean shortening of 5.4 mm (-0.04 to 16.1)
had occurred in the fracture of the femoral neck group and 5.0 mm
(-0.13 to 12.9) in the trochanteric fracture group. A wide range
of rotation occurred in both types of fracture. Right-sided trochanteric
fractures seem more rotationally stable than left-sided fractures. This prospective study shows that migration at the fracture site
occurs continuously during the first four post-operative months,
after which stabilisation occurs. This information may allow the
early recognition of patients at risk of failure of fixation. Cite this article:
We investigated a new intramedullary locking
nail that allows the distal interlocking screws to be locked to
the nail. We compared fixation using this new implant with fixation
using either a conventional nail or a locking plate in a laboratory
simulation of an osteoporotic fracture of the distal femur. A total
of 15 human cadaver femora were used to simulate an AO 33-A3 fracture
pattern. Paired specimens compared fixation using either a locking
or non-locking retrograde nail, and using either a locking retrograde
nail or a locking plate. The constructs underwent cyclical loading
to simulate single-leg stance up to 125 000 cycles. Axial and torsional
stiffness and displacement, cycles to failure and modes of failure
were recorded for each specimen. When compared with locking plate
constructs, locking nail constructs had significantly longer mean
fatigue life (75 800 cycles ( The new locking retrograde femoral nail showed better stiffness
and fatigue life than locking plates, and superior fatigue life
to non-locking nails, which may be advantageous in elderly patients. Cite this article:
The leading indication for revision total hip
arthroplasty (THA) remains aseptic loosening owing to wear. The younger,
more active patients currently undergoing THA present unprecedented
demands on the bearings. Ceramic-on-ceramic (CoC) bearings have
consistently shown the lowest rates of wear. The recent advances,
especially involving alumina/zirconia composite ceramic, have led
to substantial improvements and good results Alumina/zirconia composite ceramics are extremely hard, scratch
resistant and biocompatible. They offer a low co-efficient of friction
and superior lubrication and lower rates of wear compared with other
bearings. The major disadvantage is the risk of fracture of the
ceramic. The new composite ceramic has reduced the risk of fracture
of the femoral head to 0.002%. The risk of fracture of the liner
is slightly higher (0.02%). Assuming that the components are introduced without impingement,
CoC bearings have major advantages over other bearings. Owing to
the superior hardness, they produce less third body wear and are
less vulnerable to intra-operative damage. The improved tribology means that CoC bearings are an excellent
choice for young, active patients requiring THA. Cite this article:
The August 2014 Shoulder &
Elbow Roundup360 looks at: Myofibroblasts perhaps not implicated in post-traumatic elbow stiffness; olecranon tip biomechanically sound for coranoid reconstruction; obesity and elbow replacement don’t mix; single column plating successful for extra-articular distal humeral fractures; satisfaction not predictable in frozen shoulder; tenodesis and repair both acceptable in Grade II SLAP tears; glenoid bone grafting is effective and glenohumeral articular lesions best seen with an arthroscope.
Bioengineering reasons for increased wear and failure of metal-on-metal (MoM) bearings in hip prostheses have been described. Low wear occurs in MoM hips when the centre of the femoral head is concentric with the centre of the acetabular component and the implants are correctly positioned. Translational or rotational malpositioning of the components can lead to the contact-patch of the femoral component being displaced to the rim of the acetabular component, resulting in a ten- to 100-fold increase in wear and metal ion levels. This may cause adverse tissue reactions, loosening of components and failure of the prosthesis.
High failure rates of metal-on-metal hip arthroplasty implants have highlighted the need for more careful introduction and monitoring of new implants and for the evaluation of the safety of medical devices. The National Joint Registry and other regulatory services are unable to detect failing implants at an early enough stage. We aimed to identify validated surrogate markers of long-term outcome in patients undergoing primary total hip arthroplasty (THA). We conducted a systematic review of studies evaluating surrogate markers for predicting long-term outcome in primary THA. Long-term outcome was defined as revision rate of an implant at ten years according to National Institute of Health and Care Excellence guidelines. We conducted a search of Medline and Embase (OVID) databases. Separate search strategies were devised for the Cochrane database and Google Scholar. Each search was performed to include articles from the date of their inception to June 8, 2015.Objectives
Methods
Lengthening of the conjoined tendon of the gastrocnemius
aponeurosis and soleus fascia is frequently used in the treatment
of equinus deformities in children and adults. The Vulpius procedure
as described in most orthopaedic texts is a division of the conjoined
tendon in the shape of an inverted V. However, transverse division
was also described by Vulpius and Stoffel, and has been reported
in some clinical studies. We studied the anatomy and biomechanics of transverse division
of the conjoined tendon in 12 human cadavers (24 legs). Transverse
division of the conjoined tendon resulted in predictable, controlled
lengthening of the gastrocsoleus muscle-tendon unit. The lengthening
achieved was dependent both on the level of the cut in the conjoined
tendon and division of the midline raphé. Division at a proximal
level resulted in a mean lengthening of 15.2 mm ( Cite this article:
The October 2015 Foot &
Ankle Roundup360 looks at: TightRope in Weber C fractures; A second look at the TightRope; Incisional VAC comes of age?; Platelet-derived growth factor and ankle fusions; Achilles tendon rehab in the longer term following surgery; Telemedicine for diabetic foot ulcer
The February 2014 Shoulder &
Elbow Roundup360 looks at: whether arthroscopic acromioplasty is a cost-effective intervention; shockwave therapy in cuff tear; whether microfracture relieves short-term pain in cuff repair; the promising early results from L-PRF augmented cuff repairs; rehabilitation following cuff repair; supination strength following biceps tendon rupture; whether longer is better in humeral components; fatty degeneration in a rodent model; and the controversial acromioclavicular joint dislocation.
The October 2015 Hip &
Pelvis Roundup360 looks at: Smoking and complications in arthroplasty; Smoking cessation beneficial in arthroplasty; Intermediate care and arthroplasty; Do we still need cell salvage?; Femoroacetabular impingement in the Japanese population; Trunnionosis or taperosis and geometry; Decontamination for staphylococcus aureus works!; Policeman or opportunity? Quality improvement with registries; Death rates higher in readmission to other hospitals
Most published randomised controlled trials which
compare the rates of wear of conventional and cross-linked (XL) polyethylene
(PE) in total hip arthroplasty (THA) have described their use with
a cementless acetabular component. We conducted a prospective randomised study to assess the rates
of penetration of two distinct types of PE in otherwise identical
cemented all-PE acetabular components. A total of 100 consecutive patients for THA were randomised to
receive an acetabular component which had been either highly XL
then remelted or moderately XL then annealed. After a minimum of eight years follow-up, 38 hips in the XL group
and 30 hips in the annealed group had complete data (mean follow-up
of 9.1 years (7.6 to 10.7) and 8.7 years (7.2 to 10.2), respectively).
In the XL group, the steady state rate of penetration from one year
onwards was -0.0002 mm/year ( These results show that the yearly linear rate of femoral head
penetration can be significantly reduced by using a highly XLPE
cemented acetabular component. Cite this article:
We biomechanically investigated whether the standard dynamic hip screw (DHS) or the DHS blade achieves better fixation in bone with regard to resistance to pushout, pullout and torsional stability. The experiments were undertaken in an artificial bone substrate in the form of polyurethane foam blocks with predefined mechanical properties. Pushout tests were also repeated in cadaveric femoral heads. The results showed that the DHS blade outperformed the DHS with regard to the two most important characteristics of implant fixation, namely resistance to pushout and rotational stability. We concluded that the DHS blade was the superior implant in this study.
Many different lengths of stem are available
for use in primary total hip replacement, and the morphology of
the proximal femur varies greatly. The more recently developed shortened
stems provide a distribution of stress which closely mimics that
of the native femur. Shortening the femoral component potentially
comes at the cost of decreased initial stability. Clinical studies
on the performance of shortened cemented and cementless stems are promising,
although long-term follow-up studies are lacking. We provide an
overview of the current literature on the anatomical features of
the proximal femur and the biomechanical aspects and clinical outcomes
associated with the length of the femoral component in primary hip
replacement, and suggest a classification system for the length
of femoral stems. 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.