We present a series of 35 patients (19 men and
16 women) with a mean age of 64 years (36.7 to 75.9), who underwent
total hip replacement using the ESKA dual-modular short stem with
metal on-polyethylene bearing surfaces. This implant has a modular
neck section in addition to the modular head. Of these patients,
three presented with increasing post-operative pain due to pseudotumour
formation that resulted from corrosion at the modular neck-stem
junction. These patients underwent further surgery and aseptic lymphocytic
vaculitis associated lesions were demonstrated on histological analysis. Retrieval analysis of two modular necks showed corrosion at the
neck-stem taper. Blood cobalt and chromium levels were measured
at a mean of nine months (3 to 28) following surgery. These were
compared with the levels in seven control patients (three men and
four women) with a mean age of 53.4 years (32.1 to 64.1), who had
an identical prosthesis and articulation but with a prosthesis that
had no modularity at neck-stem junction. The mean blood levels of
cobalt in the study group were raised at 50.75 nmol/l (5 to 145)
compared with 5.6 nmol/l (2 to 13) in control patients. Corrosion at neck-stem tapers has been identified as an important
source of metal ion release and pseudotumour formation requiring
revision surgery. Finite element modelling of the dual modular stem
demonstrated high stresses at the modular stem-neck junction. Dual
modular cobalt-chrome hip prostheses should be used with caution
due to these concerns.
Systemic mastocytosis is a rare condition that often involves the bone marrow. We report the case of a patient with systemic mastocytosis who underwent total hip replacement. Technical difficulties encountered during the procedure included a narrow medullary canal and abnormally hard bone, later confirmed by laboratory measurements. Follow-up at five years showed a good clinical and radiological outcome.
Polymethylmethacrylate remains one of the most enduring materials in orthopaedic surgery. It has a central role in the success of total joint replacement and is also used in newer techniques such as percutaneous vertebroplasty and kyphoplasty. This article describes the current uses and limitations of polymethylmethacrylate in orthopaedic surgery. It focuses on its mechanical and chemical properties and links these to its clinical performance. The behaviour of antibiotic-loaded bone cement are discussed, together with areas of research that are now shedding light upon the behaviour of this unique biomaterial.
The National Institute for Clinical Excellence (NICE) produces recommendations on appropriate treatment within the National Health Service (NHS) in England and Wales. The NICE guidelines on prophylaxis for venous thromboembolism in orthopaedic surgery recommend that all patients be offered a low molecular weight heparin (LMWH). The linked hospital episode statistics of 219 602 patients were examined to determine the rates of complications following lower limb arthroplasty for the 12-month periods prior to and following the publication of these guidelines. These were compared with data from the National Joint Registry (England and Wales) regarding the use of LMWH during the same periods. There was a significant increase in the reported use of LMWH (59.5% to 67.6%, p <
0.001) following the publication of the guidelines. However, the 90-day venous thromboembolism events actually increased slightly following total hip replacement (THR, 1.69% to 1.84%, p = 0.06) and remained unchanged following total knee replacement (TKR, 1.99% to 2.04%). Return to theatre in the first 30 days for infection did not show significant changes. There was an increase in the number of patients diagnosed with thrombocytopenia, which was significant following THR (0.11% to 0.16%, p = 0.04). The recommendations from NICE are based on predicted reductions in venous thromboembolism events, reducing morbidity, mortality and costs to the NHS. The early results in orthopaedic patients do not support these predictions, but do show an increase in complications.
Between June 1991 and January 1995, 42 hydroxyapatite-coated CAD-CAM femoral components were inserted in 25 patients with inflammatory polyarthropathy, 21 of whom had juvenile idiopathic arthritis. Their mean age was 21 years (11 to 35). All the patients were reviewed clinically and radiologically at one, three and five years. At the final review at a mean of 11.2 years (8 to 13) 37 hips in 23 patients were available for assessment. A total of four femoral components (9.5%) had failed, of which two were radiologically loose and two were revised. The four failed components were in patients aged 16 years or less at the time of surgery. Hydroxyapatite-coated customised femoral components give excellent medium- to long-term results in skeletally-mature young adults with inflammatory polyarthropathy. Patients aged less than 16 years at the time of surgery have a risk of 28.5% of failure of the femoral component at approximately ten years.
Heterotopic ossification following joint replacement in the lower limb occurs in 3% to 90% of cases. Higher grades of heterotopic ossification can result in significant limitation of function and can negate the benefits of joint replacement. The understanding of the pathophysiology of this condition has improved in recent years. It would appear to be related to a combination of systemic and local factors, including over-expression of bone morphogenetic protein-4. There is currently little evidence to support the routine use of prophylaxis for heterotopic ossification in arthroplasty patients, but prophylaxis is recommended by some for high-risk patients. Radiotherapy given as one dose of 7 Gy to 8 Gy, either pre-operatively (<
four hours before) or post-operatively (within 72 hours of surgery), appears to be more effective than indometacin therapy (75 mg daily for six weeks). In cases of prophylaxis against recurrent heterotopic ossification following excision, recent work has suggested that a combination of radiotherapy and indometacin is effective. Advances in our understanding of this condition may permit the development of newer, safer treatment modalities.
United Kingdom National Institute for Health
and Clinical Excellence guidelines recommend the use of total hip replacement
(THR) for displaced intracapsular fractures of the femoral neck
in cognitively intact patients, who were independently mobile prior
to the injury. This study aimed to analyse the risk factors associated
with revision of the implant and mortality following THR, and to
quantify risk. National Joint Registry data recording a THR performed
for acute fracture of the femoral neck between 2003 and 2010 were
analysed. Cox proportional hazards models were used to investigate
the extent to which risk of revision was related to specific covariates.
Multivariable logistic regression was used to analyse factors affecting
peri-operative mortality (<
90 days). A total of 4323 procedures
were studied. There were 80 patients who had undergone revision
surgery at the time of censoring (five-year revision rate 3.25%, 95%
confidence interval 2.44 to 4.07) and 137 patients (3.2%) patients
died within 90 days. After adjusting for patient and surgeon characteristics,
an increased risk of revision was associated with the use of cementless
prostheses compared with cemented (hazard ratio (HR) 1.33, p = 0.021).
Revision was independent of bearing surface and head size. The risk
of mortality within 90 days was significantly increased with higher
American Society of Anesthesiologists (ASA) grade (grade 3: odds
ratio (OR) 4.04, p <
0.001; grade 4/5: OR 20.26, p <
0.001;
both compared with grades 1/2) and older age (≥ 75 years: OR 1.65,
p = 0.025), but reduced over the study period (9% relative risk reduction
per year). THR is a good option in patients aged <
75 years and with
ASA 1/2. Cementation of the femoral component does not adversely
affect peri-operative mortality but improves survival of the implant
in the mid-term when compared with cementless femoral components.
There are no benefits of using head sizes >
28 mm or bearings other
than metal-on-polyethylene. More research is required to determine
the benefits of THR over hemiarthroplasty in older patients and
those with ASA grades >
2.
We carried out a prospective randomised study to evaluate the blood loss in 60 patients having a total knee arthroplasty and divided randomly into two equal groups, one having a computer-assisted procedure and the other a standard operation. The surgery was carried out by a single surgeon at one institution using a uniform approach. The only variable in the groups was the use of intramedullary femoral and tibial alignment jigs in the standard group and single tracker pins of the imageless navigation system in the tibia and femur in the navigated group. The mean drainage of blood was 1351 ml (715 to 2890; 95% confidence interval (CI) 1183 to 1518) in the computer-aided group and 1747 ml (1100 to 3030; CI 1581 to 1912) in the conventional group. This difference was statistically significant (p = 0.001). The mean calculated loss of haemoglobin was 36 g/dl in the navigated group There was a highly significant reduction in blood drainage and the calculated Hb loss between the computer-assisted and the conventional techniques. This allows the ordering of less blood before the operation, reduces risks at transfusion and gives financial saving. Computer-assisted surgery may also be useful for patients in whom blood products are not acceptable.
An international faculty of orthopaedic surgeons
presented their work on the current challenges in hip surgery at
the London Hip Meeting which was attended by over
400 delegates. The topics covered included femoroacetabular impingement, thromboembolic
phenomena associated with hip surgery, bearing surfaces (including metal-on-metal
articulations), outcomes of hip replacement surgery and revision
hip replacement. We present a concise report of the current opinions
on hip surgery from this meeting with appropriate references to
the current literature.
An experimental rabbit model was used to test the null hypothesis,
that there is no difference in new bone formation around uncoated
titanium discs compared with coated titanium discs when implanted
into the muscles of rabbits. A total of three titanium discs with different surface and coating
(1, porous coating; 2, porous coating + Bonemaster (Biomet); and
3, porous coating + plasma-sprayed hydroxyapatite) were implanted
in 12 female rabbits. Six animals were killed after six weeks and
the remaining six were killed after 12 weeks. The implants with
surrounding tissues were embedded in methyl methacrylate and grinded
sections were stained with Masson-Goldners trichrome and examined
by light microscopy of coded sections.Objectives
Methods
We assessed the short- to mid-term survival of
metallic press-fit radial head prostheses in patients with radial
head fractures and acute traumatic instability of the elbow. The medical records of 42 patients (16 males, 26 females) with
a mean age of 56 years (23 to 85) with acute unstable elbow injuries,
including a fracture of the radial head requiring metallic replacement
of the radial head, were reviewed retrospectively. Survival of the
prosthesis was assessed from the radiographs of 37 patients after
a mean follow-up of 50 months (12 to 107). The functional results
of 31 patients were assessed using range-of-movement, Mayo elbow
performance score (MEPS), Disabilities of the Arm, Shoulder and
Hand (DASH) score and the RAND 36-item health survey. At the most recent follow-up 25 prostheses were still well fixed,
nine had been removed because of loosening, and three remained implanted
but were loose. The mean time from implantation to loosening was
11 months (2 to 24). Radiolucent lines that developed around the
prosthesis before removal were mild in three patients, moderate
in one and severe in five. Range of movement parameters and mass
grip strength were significantly lower in the affected elbow than
in the unaffected side. The mean MEPS score was 86 (40 to 100) and
the mean DASH score was 23 (0 to 81). According to RAND-36 scores,
patients had more pain and lower physical function scores than normal population
values. Loosening of press-fit radial head prostheses is common, occurs
early, often leads to severe osteolysis of the proximal radius,
and commonly requires removal of the prosthesis.
Peri-prosthetic patellar fracture following resurfacing
as part of total knee replacement (TKR) is an infrequent yet challenging
complication. This case-control study was performed to identify
clinical, radiological and surgical factors that increase the risk
of developing a spontaneous patellar fracture after TKR. Patellar
fractures were identified in 74 patients (88 knees) from a series
of 7866 consecutive TKRs conducted between 1998 and 2009. After excluding
those with a previous history of extensor mechanism realignment
or a clear traumatic event, a metal-backed patella, any uncemented
component or subsequent infection, the remaining 64 fractures were
compared with a matched group of TKRs with an excellent outcome
defined by the Knee Society score. The mean age of patients with
a fracture was 70 years (51 to 81) at the time of TKR. Patellar
fractures were detected at a mean of 13.4 months (2 to 84) after
surgery. The incidence of patellar fracture was found to be strongly
associated with the number of previous knee operations, greater
pre-operative mechanical malalignment, smaller post-operative patellar
tendon length, thinner post-resection patellar thickness, and a
lower post-operative Insall-Salvati ratio. An understanding of the risk factors associated with spontaneous
patellar fracture following TKR provides a valuable insight into
prevention of this challenging complication.
Inflammatory pseudotumours occasionally occur after metal-on-metal hip resurfacing and often lead to revision. Our aim was to determine the severity of this complication by assessing the outcome of revision in these circumstances and by comparing this with the outcome of other metal-on-metal hip resurfacing revisions as well as that of matched primary total hip replacements. We identified 53 hips which had undergone metal-on-metal hip resurfacing and required revision at a mean of 1.59 years (0.01 to 6.69) after operation. Of these, 16 were revised for pseudotumours, 21 for fracture and 16 for other reasons. These were matched by age, gender and diagnosis with 103 patients undergoing primary total hip replacement with the Exeter implant. At a mean follow-up of three years (0.8 to 7.2) the outcome of metal-on-metal hip resurfacing revision for pseudotumour was poor with a mean Oxford hip score of 20.9 ( The outcome of revision for pseudotumour is poor and consideration should be given to early revision to limit the extent of the soft-tissue destruction. The outcome of resurfacing revision for other causes is good.
The use of plate-and-cable constructs to treat periprosthetic fractures around a well-fixed femoral component in total hip replacements has been reported to have high rates of failure. Our aim was to evaluate the results of a surgical treatment algorithm to use these lateral constructs reliably in Vancouver type-B1 and type-C fractures. The joint was dislocated and the stability of the femoral component was meticulously evaluated in 45 type-B1 fractures. This led to the identification of nine (20%) unstable components. The fracture was considered to be suitable for single plate-and-cable fixation by a direct reduction technique if the integrity of the medial cortex could be restored. Union was achieved in 29 of 30 fractures (97%) at a mean of 6.4 months (3 to 30) in 29 type-B1 and five type-C fractures. Three patients developed an infection and one construct failed. Using this algorithm plate-and-cable constructs can be used safely, but indirect reduction with minimal soft-tissue damage could lead to shorter times to union and lower rates of complications.
We randomised 62 knees to receive either cemented or cementless versions of the Oxford unicompartmental knee replacement. The implants used in both arms of the study were similar, except that the cementless components were coated with porous titanium and hydroxyapatite. The tibial interfaces were studied with fluoroscopically-aligned radiographs. At one year there was no difference in clinical outcome between the two groups. Narrow radiolucent lines were seen at the bone-implant interfaces in 75% of cemented tibial components. These were partial in 43%, and complete in 32%. In the cementless implants, partial radiolucencies were seen in 7% and complete radiolucencies in none. These differences are statistically significant (p <
0.0001) and imply satisfactory bone ingrowth into the cementless implants.
The Bologna–Oxford (BOX) total ankle replacement
(TAR) was developed with the aim of achieving satisfactory pain-free
movement of the ankle. To date, only one single multicentre study
has reported its clinical results. The aim of this study was to
conduct an independent review of its mid-term results. We retrospectively reviewed a total of 60 prospectively followed
patients in whom 62 BOX TARs had been implanted between 2004 and
2008. We used the American Orthopedic Foot and Ankle Society (AOFAS)
score to assess the clinical results. Standardised radiographs taken
at the time of final follow-up were analysed by two observers. The
overall survival was 91.9% at a mean follow-up of 42.5 months (24
to 71). The mean AOFAS score had improved from 35.1 points (
Periprosthetic fracture of the femur is an uncommon complication after total hip replacement, but appears to be increasing. We undertook a nationwide observational study to determine the risk factors for failure after treatment of these fractures, examining patient- and implant-related factors, the classification of the fractures and the outcome. Between 1979 and 2000, 1049 periprosthetic fractures of the femur were reported to the Swedish National Hip Arthroplasty Register. Of these, 245 had a further operation after failure of their initial management. Data were collected from the Register and hospital records. The material was analysed by the use of Poisson regression models. It was found that the risk of failure of treatment was reduced for Vancouver type B2 injuries (p = 0.0053) if revision of the implant was undertaken (p = 0.0033) or revision and open reduction and internal fixation (p = 0.0039) were performed. Fractures classified as Vancouver type B1 had a significantly higher risk of failure (p = 0.0001). The strongest negative factor was the use of a single plate for fixation (p = 0.001). The most common reasons for failure in this group were loosening of the femoral prosthesis, nonunion and re-fracture. It is probable that many fractures classified as Vancouver type B1 (n = 304), were in reality type B2 fractures with a loose stem which were not recognised. Plate fixation was inadequate in these cases. The difficulty in separating type B1 from type B2 fractures suggests that the prosthesis should be considered as loose until proven otherwise.
In this prospective study we studied the effect
of the inclination angle of the acetabular component on polyethylene wear
and component migration in cemented acetabular sockets using radiostereometric
analysis. A total of 120 patients received either a cemented Reflection
All-Poly ultra-high-molecular-weight polyethylene or a cemented
Reflection All-Poly highly cross-linked polyethylene acetabular
component, combined with either cobalt–chrome or Oxinium femoral
heads. Femoral head penetration and migration of the acetabular
component were assessed with repeated radiostereometric analysis
for two years. The inclination angle was measured on a standard
post-operative anteroposterior pelvic radiograph. Linear regression
analysis was used to determine the relationship between the inclination
angle and femoral head penetration and migration of the acetabular component. We found no relationship between the inclination angle and penetration
of the femoral head at two years’ follow-up (p = 0.9). Similarly,
our data failed to reveal any statistically significant correlation
between inclination angle and migration of these cemented acetabular
components (p = 0.07 to p = 0.9).
We compared the clinical and radiological outcomes
of two cementless femoral stems in the treatment of patients with
a Garden III or IV fracture of the femoral neck. A total of 70 patients At final follow-up there were no statistically significant differences
between the short anatomical and the conventional stems with regard
to the mean Harris hip score (85.7 (66 to 100) Our study demonstrated that despite the poor bone quality in
these elderly patients with a fracture of the femoral neck, osseo-integration
was obtained in all hips in both groups. However, the incidence
of thigh pain, pulmonary microemboli and peri-prosthetic fracture
was significantly higher in the conventional stem group than in
the short stem group.