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:
Most hip fractures treated with modern internal
fixation techniques will heal. However, failures occasionally occur and
require revision procedures. Salvage strategies employed during
revision are based on whether the fixation failure occurs in the
femoral neck, or in the intertrochanteric region. Patient age and
remaining bone stock also influence decision making. For fractures
in young patients, efforts are generally focused on preserving the
native femoral head via osteotomies and repeat internal fixation.
For failures in older patients, some kind of hip replacement is
usually selected. Disuse osteopenia, deformity, bone loss, and stress-risers
from previous internal fixation devices all pose technical challenges
to successful reconstruction. Attention to detail is important in
order to minimise complications. In the majority of cases, good
outcomes have been reported for the various salvage strategies. Cite this article:
Pelvic discontinuity represents a rare but challenging
problem for orthopaedic surgeons. It is most commonly encountered
during revision total hip replacement, but can also result from
an iatrogentic acetabular fracture during hip replacement. The general
principles in management of pelvic discontinuity include restoration
of the continuity between the ilium and the ischium, typically with
some form of plating. Bone grafting is frequently required to restore
pelvic bone stock. The acetabular component is then impacted, typically
using an uncemented, trabecular metal component. Fixation with multiple
supplemental screws is performed. For larger defects, a so-called
‘cup–cage’ reconstruction, or a custom triflange implant may be
required. Pre-operative CT scanning can greatly assist in planning
and evaluating the remaining bone stock available for bony ingrowth.
Generally, good results have been reported for constructs that restore
stability to the pelvis and allow some form of biologic ingrowth. Cite this article:
We hypothesised that cells obtained via a Reamer–Irrigator–Aspirator
(RIA) system retain substantial osteogenic potential and are at
least equivalent to graft harvested from the iliac crest. Graft
was harvested using the RIA in 25 patients (mean age 37.6 years
(18 to 68)) and from the iliac crest in 21 patients (mean age 44.6
years (24 to 78)), after which ≥ 1 g of bony particulate graft material
was processed from each. Initial cell viability was assessed using Trypan
blue exclusion, and initial fluorescence-activated cell sorting
(FACS) analysis for cell lineage was performed. After culturing
the cells, repeat FACS analysis for cell lineage was performed and
enzyme-linked immunosorbent assay (ELISA) for osteocalcin, and Alizarin
red staining to determine osteogenic potential. Cells obtained via
RIA or from the iliac crest were viable and matured into mesenchymal
stem cells, as shown by staining for the specific mesenchymal antigens
CD90 and CD105. For samples from both RIA and the iliac crest there
was a statistically significant increase in bone production (both
p <
0.001), as demonstrated by osteocalcin production after induction. Medullary autograft cells harvested using RIA are viable and
osteogenic. Cell viability and osteogenic potential were similar
between bone grafts obtained from both the RIA system and the iliac
crest. Cite this article:
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:
Options for the treatment of subcapital femoral
neck fractures basically fall into two categories: internal fixation
or arthroplasty (either hemiarthroplasty or total hip arthroplasty).
Historically, the treatment option has been driven by a diagnosis-related approach
(non-displaced neck fractures versus displaced neck fractures).
More recently, the traditional paradigm has changed. Instead of
a diagnosis-related approach, it has become more of a patient-related
approach. Treatment options take in to consideration the patient’s age,
functional demands, and individual risk profile. A simple algorithm
can be helpful in terms of directing the treatment. Non-displaced
fractures, regardless of age of the patient, should be treated with
closed reduction and internal fixation. For displaced femoral neck fractures,
the treatment differs depending on the age of the patient. The younger
patient should be treated with urgent ORIF with the goal of an anatomic
reduction. For displaced femoral neck fractures in the elderly,
cognitive function should be determined. For those who are cognitively
functioning, total hip arthroplasty appears to be the best option.
In the cognitively dysfunctional, a bipolar hemiarthroplasty or
a total hip arthroplasty with use of larger heads (32 mm or 36 mm)
and/or constrained sockets are a viable option.
There are no recent studies comparing cable with
wire for the fixation of osteotomies or fractures in total hip replacement
(THR). Our objective was to evaluate the five-year clinical and
radiological outcomes and complication rates of the two techniques.
We undertook a review including all primary and revision THRs performed
in one hospital between 1996 and 2005 using cable or wire fixation.
Clinical and radiological evaluation was performed five years post-operatively.
Cables were used in 51 THRs and wires in 126, and of these, 36 THRs
with cable (71%) and 101 with wire (80%) were evaluated at follow-up.
The five-year radiographs available for 33 cable and 91 wire THRs
revealed rates of breakage of fixation of 12 of 33 (36%) and 42
of 91 (46%), respectively. With cable there was a significantly
higher risk of metal debris (68% In conclusion, we found a higher incidence of complications and
a trend towards increased infection and foreign-body reaction with
the use of cables.
Many tumors metastasise to bone, therefore, pathologic
fracture and impending pathologic fractures are common reasons for
orthopedic consultation. Having effective treatment strategies is
important to avoid complications, and relieve pain and preserve
function. Thorough pre-operative evaluation is recommended for medical
optimization and to ensure that the lesion is in fact a metastasis
and not a primary bone malignancy. For impending fractures, various scoring
systems have been proposed to determine the risk of fracture, and
therefore the need for prophylactic stabilisation. Lower score lesions
can often be treated with radiation, while more problematic lesions
may require internal fixation. Intramedullary fixation is generally
preferred due to favorable biomechanics. Arthroplasty may be required
for lesions with massive bony destruction where internal fixation
attempts are likely to fail. Radiation may also be useful postoperatively
to minimise construct failure due to tumor progression.
Osteolysis remains a common reason for revision
after total hip arthroplasty (THA). For osteolysis associated with loose
cups, revision is indicated. For osteolysis around a well-fixed
cup, the decision is more controversial. The data available data
support retention of the cupwith lesional treatment, working through
screw holes and access channels for debridement and grafting. The
choice of graft material to fill defects, if any, remains controversial. Several
studies demonstrate good survivorship with cup retention strategies.
Complete revision allows more complete debridement of the lesion
and better graft fill, and allows implantation of a modern cup,
typically with a full line of liners and bearing surfaces available.
Additionally, revision allows fine tuning of the orientation of
the cup, which may be advantageous for optimising hip stability.
The author prefers to retain a well-fixed cup if it meets the following
criteria: it is well-fixed to intra-operative testing, it is well-positioned,
it is of sufficient size to allow insertion of a new liner with
a reasonable head size, new liners are available, and the hip is
stable to intra-operative trialing after liner insertion.
The coronoid and collateral ligaments are key elbow stabilizers. When repair of comminuted coronoid fractures is not possible, prosthetic replacement may restore elbow stability. A coronoid prosthesis has been designed with an extended tip in an effort to augment elbow stability in the setting of residual collateral ligament insufficiency. The purpose of this biomechanical study, therefore, was to compare an anatomic coronoid replacement with an extended tip implant both with and without ligament insufficiency. Two coronoid prostheses were designed and developed based on CT-derived images adjusted for cartilage thickness: an anatomical implant and an extended-tip implant. Passive elbow extension was performed in 7 cadaveric arms in the varus and valgus positions. Varus-valgus laxity of the ulna relative to the humerus was quantified with a tracking system with an intact coronoid, a 40% coronoid deficiency, an anatomical prosthesis, and an extended prosthesis, with the collateral ligaments sectioned and repaired.Purpose
Method
Limited information is available regarding the functional outcomes of radial head fractures managed with open reduction and internal fixation (ORIF). The purpose of this study was to determine the functional outcomes of radial head fractures treated with ORIF. Fifty-two patients, with a mean age of 4412 years, who were treated with radial head ORIF were evaluated at a mean of 4.42.4 years. Thirty were isolated radial head fractures (Group A), 13 (Group B) were associated with a complex fracture-dislocation (terrible triad variants), and 5 (Group C) were associated with a proximal ulnar fracture (Monteggia/trans-olecranon variants). Fourty-four were partial articular fractures and 8 were complete articular fractures. Outcomes were assessed with physical and radiographic examination, and validated self-reported questionnaires.Purpose
Method
Radial head implant over-lengthening, a common cause of capitellar wear and clinical failure, is difficult to diagnose using radiographs of the injured elbow. The purpose of this study was to determine if a novel measurement technique based on contralateral elbow radiographs, termed the RACER method, could be used to accurately estimate the magnitude of radial head implant over-lengthening. Part I of this study examined the side-to-side consistency of radiographic landmarks used in the measurement technique. Part II of this study validated the technique using simulated radial head implant over-lengthening in a cadaveric model. Part I: A side-to-side comparison of elbow joint dimensions was performed in 50 patients (100 radiographs). Part II: Radial head prostheses of varying lengths (0,+2mm,+4mm,+6mm,+8mm) were implanted in 4 paired cadaveric specimens (8 elbows). Radiographs were obtained and measurements were performed by 2 examiners blinded to implant size to determine if contralateral radiographs could diagnose and provide a valid estimate of the magnitude of implant over-lengthening. Intra and inter-rater reliability was determined.Purpose
Method
There have been a number of described techniques for sizing the diameter of radial head implants. All of these techniques, however, are dependent on measurements of the excised native radial head. When accurate sizing is not possible due to extensive comminution or due to a previous radial head excision, it has been postulated that the proximal radioulnar joint (PRUJ) may be used as an intraoperative landmark for correct sizing. The purpose of this study was to: 1) determine if the PRUJ could be used as a reliable landmark for radial head implant diameter sizing when the native radial head in unavailable, and (2) determine the reliability of measurements of the excised radial head. Twenty-seven fresh-frozen denuded ulnae and their corresponding radial heads (18 males, 9 females) were examined. The maximum diameter (MaxD), minimum diameter (MinD) and dish diameter (DD) of the radial heads were measured twice, 3–5 weeks apart, using digital calipers. Two fellowship-trained upper extremity surgeons, an upper extremity fellow and a senior orthopedic resident were then asked to independently select a radial head implant diameter based on the congruency of the radius of curvature of the PRUJ to that of the radial head trial implants. The examiners were blinded to the native radial head dimensions. This selection was repeated 3–5 weeks later by two of the investigators. Correlation between radial head measurements and radial head implant diameter sizes was assessed using Pearsons correlation coefficient (PCC) and inter and intra-observer reliability were assessed using intra-class correlation coefficient (ICC).Purpose
Method
Current coronoid fracture classification systems are based on fragment size and configuration using plain radiographs and/or CT. During surgery, coronoid fracture fragments appear much larger than anticipated because cartilage is radiolucent and therefore not taken into account with preoperative imaging. The purpose of this study was to quantify the articular cartilage thickness of the coronoid process, with reference to coronoid fracture classifications. Twenty-four cadaveric ulnae were dissected, imaged, and analyzed using the OsiriX software program (3.6–64 bit, Geneva). Thirteen identifiable landmarks were chosen on the coronoid, olecranon and proximal radioulnar joint to measure articular cartilage thickness. Intra-observer and inter-observer reliability were calculated.Purpose
Method
The coronoid process is an integral component for elbow stability. In the setting of a comminuted coronoid fracture, where repair is not possible, a prosthetic device may be beneficial in restoring elbow stability. The hypothesis of this in-vitro biomechanical study was that an anatomic coronoid prosthesis would restore stability to the coronoid deficient elbow. A metal coronoid prosthesis was designed and developed based on CT-derived images adjusted for cartilage thickness. The kinematics and stability of eight fresh-frozen male cadaveric arms (mean age 77.4 years, range 69–92 years) were quantified in the intact state; after collateral ligament sectioning and repair (control state); after a simulated 40% transverse coronoid fracture; and after implantation of a coronoid prosthesis. Elbow flexion was simulated passively with the arm oriented in the varus position and the forearm in pronation. Varus-valgus angulation (VV) and internal-external rotation (IE) of the ulna relative to the humerus were quantified with an electromagnetic tracking system (Flock of Birds, Ascension Technologies, Burlington, VT, static accuracy: 1.8mm position, 0.5 orientation).Purpose
Method
Capitellum hemiarthroplasty is an emerging concept. The current metallic capitellar implants have spherical surface shapes, but the native capitellum is not spherical. This study evaluated the effect of capitellar implant shape on the contact mechanics of the radiocapitellar joint when articulating with the native radial head. Eight paired radii and humeri were potted in a custom jig. Articular casts were made with medium-viscosity resin while 85 N of axial load was applied to the reduced radiocapitellar joint at 0, 45, and 90 of elbow flexion, and at neutral, 50 pronation and 50 supination at each flexion angle. The native radiocapitellar articulation was compared to capitellar hemiarthroplasties of two surface designs (anatomical and spherical). Contact area and shape (circularity) were determined. Circularity was defined as the ratio of the minor axis and major axis of the shape.Purpose
Method
Release of tight lateral structures is an integral part of balancing the valgus knee during knee replacement surgery. The posterolateral capsule is released through an inside-out technique. The common peroneal nerve is in close proximity to the capsule during this step. This study was undertaken to determine the distance of the nerve and the safe level for the posterolateral release. MR scans of the knee of 100 patients were evaluated. The age range of selected patients was 50 to 70 years. The distance of the nerve was measured to the closest point on the posterolateral capsule. Two separate measurements were taken - one 9mm above the joint line indicating the distal femoral resection level and the other 9mm distal to the joint line indicating the level of tibial resection. A third point was at the joint line level. The position of the nerve was also recorded in relation to the cross section of the femur/tibia on a ‘clock-like’ reference.Purpose of the study
Methods
Rapid prototyping (RP), especially useful in surgical specialities involving critical three-dimensional relationships, has recently become cheaper to access both in terms of file processing and commercially available printing resources. One potential problem has been the accuracy of models generated. We performed computed tomography on a cadaveric human patella followed by data conversion using open source software through to selective-laser-sintering of a polyamide model, to allow comparative morphometric measurements (bone No significant differences in the dimensional measurements could be demonstrated. These data provide us with optimism as to the accuracy of the technology, and the feasibility of using RP cheaply to generate appropriate models for operative rehearsal of intricate orthopaedic procedures.
Hip resurfacing arthroplasty is an established and effective intervention for osteoarthritis of the hip in the young active patient, relying on the principle of femoral bone-stock preservation. A recognised mode of failure is neck thinning leading to radiological evidence of neck collapse and clinical failure. We report on a series of these slow-neck-failure patients and highlight the increased incidence of this phenomenon in post-menopausal female patients. This is a single operator, single implant series; 172 cases were identified from databases at our institution. 76 were female, mean (SD) age 52 (7) years. 96 were male, mean (SD) age 51(12) years. 15 (8.7%) patients required revision. 12 (80%) were female, 9 (75%) of these were due to slow neck failure. In the men one patient developed ALVAL requiring removal of his bilateral hip resurfacings, the other failure mode was early femoral neck failure. Mean time to failure was 6 months in men and 37 months in women. This difference in failure rates is also seen in the NJR figures. This review confirms the relatively high incidence of premature failure in post-menopausal females. NICE guidance in 2003, currently under review, stated that resurfacing is indicated in male patients up to 65 and female patients up to 60. As a result of this study we are currently advising post-menopausal patients that this risk of early failure may make total hip replacement a preferable option to resurfacing arthroplasty.
Osteonecrosis (ON) is a disease that ultimately results in bone collapse. We investigated the correlation between SNPs and osteonecrosis. In this study, 109 patients with systematic lupus erythematosus (SLE) (21 with and 88 without osteonecrosis) were collected for genotype analysis of 7 genes including Introduction
Methods