The mechanisms controlling and limiting movement and serving to transmit load between the femur and the tibia are discussed. Having accounted for the transmission of all components of force and couple across the joint and noted the load-bearing role of the menisci, some principles which might guide the design of knee prostheses are deduced. It is shown that current designs transgress some of these principles. An experimental prosthesis is then described, which incorporates analogues of the natural menisci. The possible practical application of this novel principle has been studied in cadaveric human joints and in living patients.
The aim of this study was to identify the effect of the manufacturing characteristics of polyethylene acetabular liners on the survival of cementless and hybrid total hip arthroplasty (THA). Prospective cohort study using linked National Joint Registry (NJR) and manufacturer data. The primary endpoint was revision for aseptic loosening. Cox proportional hazard regression was the primary analytical approach. Manufacturing variables included resin type, crosslinking radiation dose, terminal sterilization method, terminal sterilization radiation dose, stabilization treatment, total radiation dose, packaging, and face asymmetry. Total radiation dose was further divided into G1 (no radiation), G2 (> 0 Mrad to < 5 Mrad), G3 (≥ 5 Mrad to < 10 Mrad), and G4 (≥ 10 Mrad).Aims
Methods
The aim of this study was to conduct the largest low contact stress (LCS) retrieval study to elucidate the failure mechanisms of the Porocoat and Duofix femoral component. The latter design was voluntarily recalled by the manufacturer. Uncemented LCS explants were divided into three groups: Duofix, Porocoat, and mixed. Demographics, polyethylene wear, tissue ingrowth, and metallurgical analyses were performed.Aims
Materials and Methods
The aim of this study was to compare the survivorship and radiographic
outcomes at ten-year follow-up of three prospective consecutive
series of patients each of which received a different design of
cementless femoral components for total hip arthroplasty (THA). In Cohort 1, 91 consecutive patients (100 hips) underwent THA
with a cementless porous-coated anatomic femoral stem (PCA) between
October 1983 and January 1986. In Cohort 2, 86 consecutive patients
(100 hips) underwent THA with an extensively porous-coated cementless
femoral stem (Prodigy) between June 1994 and October 1997. In Cohort
3, 88 consecutive patients (100 hips) underwent THA with a proximally
porous-coated triple-tapered cementless stem (Summit) between April
2002 and October 2003. All three groups underwent prospective clinical
and radiographic evaluation.Aims
Patients and Methods
Progressive retroversion of a cemented stem is
predictive of early loosening and failure. We assessed the relationship
between direct post-operative stem anteversion, measured with CT,
and the resulting rotational stability, measured with repeated radiostereometric
analysis over ten years. The study comprised 60 cemented total hip
replacements using one of two types of matt collared stem with a
rounded cross-section. The patients were divided into three groups
depending on their measured post-operative anteversion (<
10°,
10° to 25°, >
25°). There was a strong correlation between direct
post-operative anteversion and later posterior rotation. At one
year the <
10° group showed significantly more progressive retroversion
together with distal migration, and this persisted to the ten-year
follow-up. In the <
10° group four of ten stems (40%) had been
revised at ten years, and an additional two stems (20%) were radiologically
loose. In the ‘normal’ (10° to 25°) anteversion group there was
one revised (3%) and one loose stem (3%) of a total of 30 stems,
and in the >
25° group one stem (5%) was revised and another loose (5%)
out of 20 stems. This poor outcome is partly dependent on the design
of this prosthesis, but the results strongly suggest that the initial
rotational position of cemented stems during surgery affects the
subsequent progressive retroversion, subsidence and eventual loosening.
The degree of retroversion may be sensitive to prosthetic design
and stem size, but <
10° of anteversion appears deleterious to
the long-term outcome for cemented hip prosthetic stems. Cite this article:
Aims. Instability continues to be a troublesome complication after total hip arthroplasty (THA). Patient-related risk factors associated with a higher dislocation risk include the preoperative diagnosis, an age of 75 years or older, high body mass index (BMI), a history of alcohol abuse, and neurodegenerative diseases. The goal of this study was to assess the dislocation rate, radiographic outcomes, and complications of patients stratified as high-risk for dislocation who received a dual mobility (DM) bearing in a primary THA at a minimum follow-up of two years. Materials and Methods. We performed a retrospective review of a consecutive series of DM THA performed between 2010 and 2014 at our institution (Hospital for Special Surgery, New York, New York) by a single, high-volume orthopaedic surgeon employing a single
Literature surrounding artificial intelligence (AI)-related applications for hip and knee arthroplasty has proliferated. However, meaningful advances that fundamentally transform the practice and delivery of joint arthroplasty are yet to be realized, despite the broad range of applications as we continue to search for meaningful and appropriate use of AI. AI literature in hip and knee arthroplasty between 2018 and 2021 regarding image-based analyses, value-based care, remote patient monitoring, and augmented reality was reviewed. Concerns surrounding meaningful use and appropriate methodological approaches of AI in joint arthroplasty research are summarized. Of the 233 AI-related orthopaedics articles published, 178 (76%) constituted original research, while the rest consisted of editorials or reviews. A total of 52% of original AI-related research concerns hip and knee arthroplasty (n = 92), and a narrative review is described. Three studies were externally validated. Pitfalls surrounding present-day research include conflating vernacular (“AI/machine learning”), repackaging limited registry data, prematurely releasing internally validated prediction models, appraising model architecture instead of inputted data, withholding code, and evaluating studies using antiquated regression-based guidelines. While AI has been applied to a variety of hip and knee arthroplasty applications with limited clinical impact, the future remains promising if the question is meaningful, the methodology is rigorous and transparent, the data are rich, and the model is externally validated. Simple checkpoints for meaningful AI adoption include ensuring applications focus on: administrative support over clinical evaluation and management; necessity of the advanced model; and the novelty of the question being answered. Cite this article:
This study compared patient-reported outcomes of three total knee arthroplasty (TKA) designs from one manufacturer: one cruciate-retaining (CR) design, and two cruciate-sacrificing designs, anterior-stabilized (AS) and posterior-stabilized (PS). Patients scheduled for primary TKA were included in a single-centre, prospective, three-armed, blinded randomized trial (n = 216; 72 per group). After intraoperative confirmation of posterior cruciate ligament (PCL) integrity, patients were randomly allocated to receive a CR, AS, or PS design from the same TKA system. Insertion of an AS or PS design required PCL resection. The primary outcome was the mean score of all five subscales of the Knee injury and Osteoarthritis Outcome Score (KOOS) at two-year follow-up. Secondary outcomes included all KOOS subscales, Oxford Knee Score, EuroQol five-dimension health questionnaire, EuroQol visual analogue scale, range of motion (ROM), and willingness to undergo the operation again. Patient satisfaction was also assessed.Aims
Methods
The aim of this study was to estimate the clinical and economic burden of dislocation following primary total hip arthroplasty (THA) in England. This retrospective evaluation used data from the UK Clinical Practice Research Datalink database. Patients were eligible if they underwent a primary THA (index date) and had medical records available 90 days pre-index and 180 days post-index. Bilateral THAs were excluded. Healthcare costs and resource use were evaluated over two years. Changes (pre- vs post-THA) in generic quality of life (QoL) and joint-specific disability were evaluated. Propensity score matching controlled for baseline differences between patients with and without THA dislocation.Aims
Methods
The aim of this study was to investigate the outcome of periprosthetic fractures of the humerus and to assess the uniformity of the classifications used for these fractures (including those around elbow and/or shoulder arthroplasties) by performing a systematic review of the literature. A systematic search was conducted using the National Institute for Health and Care Excellence Healthcare Databases Advance Search. For inclusion, studies had to report clinical outcomes following the management of periprosthetic fractures of the humerus. The protocol was registered on the PROSPERO database.Aims
Methods
The aim of this study was to investigate the feasibility of application of a 3D-printed megaprosthesis with hemiarthroplasty design for defects of the distal humerus or proximal ulna following tumour resection. From June 2018 to January 2020, 13 patients with aggressive or malignant tumours involving the distal humerus (n = 8) or proximal ulna (n = 5) were treated by en bloc resection and reconstruction with a 3D-printed megaprosthesis with hemiarthroplasty, designed in our centre. In this paper, we summarize the baseline and operative data, oncological outcome, complication profiles, and functional status of these patients.Aims
Methods
We present a patient who underwent delayed sub-periosteal hemipelvectomy for control of infection and to enable soft-tissue cover after trauma. At four months after amputation, clinical examination and radiographs demonstrated almost complete re-ossification of the hemipelvis. This has allowed the patient to regain sitting balance and to use a walking
The use and variety of stemless humeral components in anatomical total shoulder arthroplasty (TSA) have proliferated since their advent in 2004. Early outcomes are reassuring but independent mid-term results are scarce. This independent study reports a consecutive series of 143 Eclipse stemless shoulder prostheses with a minimum five-year (5 to 10) follow-up. Outcomes of 143 procedures undertaken for all indications in 131 patients were reviewed, with subset analysis of those for osteoarthritis (OA) (n = 99). The primary outcome was the Oxford Shoulder Score (OSS) at a minimum of five years. Secondary outcomes were ranges of motion and radiological analysis of humeral radiolucency, rotator cuff failure, and glenoid loosening.Aims
Methods
Reverse total shoulder arthroplasty (RTSA) using trabecular metal (TM)-backed glenoid implants has been introduced with the aim to increase implant survival. Only short-term reports on the outcomes of TM-RTSA have been published to date. We aim to present the seven-year survival of TM-backed glenoid implants along with minimum five-year clinical and radiological outcomes. All consecutive elective RTSAs performed at a single centre between November 2008 and October 2014 were reviewed. Patients who had primary TM-RTSA for rotator cuff arthropathy and osteoarthritis with deficient cuff were included. A total of 190 shoulders in 168 patients (41 male, 127 female) were identified for inclusion at a mean of 7.27 years (SD 1.4) from surgery. The primary outcome was survival of the implant with all-cause revision and aseptic glenoid loosening as endpoints. Secondary outcomes were clinical, radiological, and patient-related outcomes with a five-year minimum follow-up.Aims
Methods
This systematic review asked which patterns of complications are associated with the three reverse total shoulder arthroplasty (RTSA) prosthetic designs, as classified by Routman et al, in patients undergoing RTSA for the management of cuff tear arthropathy, massive cuff tear, osteoarthritis, and rheumatoid arthritis. The three implant design philosophies investigated were medial glenoid/medial humerus (MGMH), medial glenoid/lateral humerus (MGLH), and lateral glenoid/medial humerus (LGMH). A systematic review of the literature was performed via a search of MEDLINE and Embase. Two reviewers extracted data on complication occurrence and patient-reported outcome measures (PROMs). Meta-analysis was conducted on the reported proportion of complications, weighted by sample size, and PROMs were pooled using the reported standardized mean difference (SMD). Quality of methodology was assessed using Wylde’s non-summative four-point system. The study was registered with PROSPERO (CRD42020193041).Aims
Methods
The results of proximal humeral replacement following trauma are substantially worse than for osteoarthritis or rheumatoid arthritis. The stable reattachment of the lesser and greater tuberosity fragments to the rotator cuff and the restoration of shoulder biomechanics are difficult. In 1992 we developed a
Modern total knee arthroplasty (TKA) prostheses are designed to restore near normal kinematics including high flexion. Kneeling is a high flexion, kinematically demanding activity after TKA. The debate about design choice has not yet been informed by six-degrees-of-freedom in vivo kinematics. This prospective randomized clinical trial compared kneeling kinematics in three TKA designs. In total, 68 patients were randomized to either a posterior stabilized (PS-FB), cruciate-retaining (CR-FB), or rotating platform (CR-RP) design. Of these patients, 64 completed a minimum one year follow-up. Patients completed full-flexion kneeling while being imaged using single-plane fluoroscopy. Kinematics were calculated by registering the 3D implant models onto 2D-dynamic fluoroscopic images and exported for analysis.Aims
Methods
The combination of an irreparable tear of the rotator cuff and destructive arthritis of the shoulder joint may cause severe pain, disability and loss of independence in the aged. Standard anatomical shoulder replacements depend on a functioning rotator cuff, and hence may fail in the presence of tears in the cuff. Many designs of non-anatomical constrained or semi-constrained prostheses have been developed for cuff tear arthropathy, but have proved unsatisfactory and were abandoned. The DePuy Delta III reverse
The objective of this study was to compare the two-year migration pattern and clinical outcomes of a total knee arthroplasty (TKA) with an asymmetrical tibial design (Persona PS) and a well-proven TKA with a symmetrical tibial design (NexGen LPS). A randomized controlled radiostereometric analysis (RSA) trial was conducted including 75 cemented posterior-stabilized TKAs. Implant migration was measured with RSA. Maximum total point motion (MTPM), translations, rotations, clinical outcomes, and patient-reported outcome measures (PROMs) were assessed at one week postoperatively and at three, six, 12, and 24 months postoperatively.Aims
Methods
Many knee replacement prostheses, embodying various principles of design, are now available and there is need for a method by which valid comparisons of results can be made. An important criterion of success is durability, so the length of time the prostheses have been in situ must be taken into account. Such a method is proposed here and is applied to the results of 673 knee replacements, of nine different types, implanted at the same hospital between 1970 and 1983. A prosthesis was considered to have failed if it had been removed or persistently caused severe pain. Two types of prosthesis were found to be significantly less successful than the other seven, between which none consistently showed significant superiority. Results for the seven types were similar despite the facts that they had been used for knees with different degrees of damage, some as secondary implants, and that they were of different design and at different stages of technical development. The more recently introduced types of
Periprosthetic fractures (PPFs) around cemented taper-slip femoral prostheses often result in a femoral component that is loose at the prosthesis-cement interface, but where the cement-bone interface remains well-fixed and bone stock is good. We aim to understand how best to classify and manage these fractures by using a modification of the Vancouver classification. We reviewed 87 PPFs. Each was a first episode of fracture around a cemented femoral component, where surgical management consisted of revision surgery. Data regarding initial injury, intraoperative findings, and management were prospectively collected. Patient records and serial radiographs were reviewed to determine fracture classification, whether the bone cement was well fixed (B2W) or loose (B2L), and time to fracture union following treatment.Aims
Methods
Enhanced perioperative protocols have significantly improved patient recovery following primary total knee arthroplasty (TKA). Little has been investigated the effectiveness of these protocols for revision TKA (RTKA). We report on a matched group of aseptic revision and primary TKA patients treated with an identical pain and rehabilitation programmes. Overall, 40 aseptic full-component RTKA patients were matched (surgical date, age, sex, and body mass index (BMI)) to a group of primary cemented TKA patients. All RTKAs had new uncemented stemmed femoral and tibial components with metaphyseal sleeves. Both groups were treated with an identical postoperative pain protocol. Patients were followed for at least two years. Knee Society Scores (KSS) at six weeks and at final follow-up were recorded for both groups.Aims
Methods
The aim of this meta-analysis was to compare the outcome of total elbow arthroplasty (TEA) undertaken for rheumatoid arthritis (RA) with TEA performed for post-traumatic conditions with regard to implant failure, functional outcome, and perioperative complications. We completed a comprehensive literature search on PubMed, Web of Science, Embase, and the Cochrane Library and conducted a systematic review and meta-analysis. Nine cohort studies investigated the outcome of TEA between RA and post-traumatic conditions. The preferred reporting items for systematic reviews and meta-analysis (Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA)) guidelines and Newcastle-Ottawa scale were applied to assess the quality of the included studies. We assessed three major outcome domains: implant failures (including aseptic loosening, septic loosening, bushing wear, axle failure, component disassembly, or component fracture); functional outcomes (including arc of range of movement, Mayo Elbow Performance Score (MEPS), and the Disabilities of the Arm, Shoulder and Hand (DASH) questionnaire), and perioperative complications (including deep infection, intraoperative fracture, postoperative fracture, and ulnar neuropathy).Aims
Materials and Methods
The purpose of this study was to report the long-term results of extendable endoprostheses of the humerus in children after the resection of a bone sarcoma. A total of 35 consecutive patients treated with extendable endoprosthetic replacement of the humerus in children were included. There were 17 boys and 18 girls in the series with a median age at the time of initial surgery of nine years (interquartile range (IQR) 7 to 11).Aims
Methods
We describe two cases of fracture of Corin Taper-Fit stems used for cement-in-cement revision of congenital dysplasia of the hip. Both prostheses were implanted in patients in their 50s, with high offsets (+7.5 mm and +3.5 mm), one with a large diameter (48 mm) head and one with a constrained acetabular component. Fracture of the stems took place at nine months and three years post-operatively following low-demand activity. Both fractures occurred at the most medial of the two stem introducer holes in the neck of the
The Denham knee replacement is a relatively simple unconstrained
We report our early experience with a new peri-acetabular reconstruction endoprosthesis used for pelvic reconstruction after tumour resection. The outcome of 21 patients who underwent limb salvage following type II pelvic resection and reconstruction using the peri-acetabular reconstruction prosthesis between 2000 and 2006 was retrospectively reviewed. This
We present a study of 67 Oxford bicompartmental total knee replacements performed at a district general hospital. In this general orthopaedic unit, 57 of the knees (85%) had significant relief of pain with a mean flexion range of 95 degrees and a mean flexion deformity of only 9 degrees. There was a noticeable difference between osteoarthritic and rheumatoid knees. Poor results could be directly related to an avoidable postoperative complication. The results of this independent assessment may be compared favourably with the previously published series from the specialist centre at which the
Various prostheses for total replacement of the first metatarsophalangeal joint for painful hallux valgus and hallux rigidus are briefly discussed. Altogether, the results of eighty-six replacements in sixty-nine patients have been recorded after an average interval of two years. In seventy-eight operations a Silastic*
Aims
Patients and Methods
As the population ages, there is projected to be an increase in the level of demand for total knee arthroplasty (TKA) in octogenarians. We aimed to explore whether those aged ≥ 80 years achieved similar improvements in physical function to younger patients while also comparing the rates of length of stay (LOS), discharge to rehabilitation, postoperative complications, and mortality following TKA in older and younger patients. Patients from one institution who underwent primary elective TKA between 1 January 2006 and 31 December 2014 were dichotomized into those ≥ 80 years old (n = 359) and those < 80 years old (n = 2479) for comparison. Multivariable regression was used to compare the physical status component of the 12-Item Short-Form Health Survey (SF-12), LOS, discharge to rehabilitation, complications, and mortality between the two groups.Aims
Patients and Methods
The aim of this study was to identify patient- and surgery-related
risk factors for sustaining an early periprosthetic fracture following
primary total hip arthroplasty (THA) performed using a double-tapered
cementless femoral component (Bi-Metric femoral stem; Biomet Inc.,
Warsaw, Indiana). A total of 1598 consecutive hips, in 1441 patients receiving
primary THA between January 2010 and June 2015, were retrospectively
identified. Level of pre-operative osteoarthritis, femoral Dorr
type and cortical index were recorded. Varus/valgus placement of
the stem and canal fill ratio were recorded post-operatively. Periprosthetic
fractures were identified and classified according to the Vancouver
classification. Regression analysis was performed to identify risk
factors for early periprosthetic fracture.Aims
Patients and Methods
The aim of this to study was to compare the previously unreported
long-term survival outcome of the Oxford medial unicompartmental
knee arthroplasty (UKA) performed by trainee surgeons and consultants. We therefore identified a previously unreported cohort of 1084
knees in 947 patients who had a UKA inserted for anteromedial knee
arthritis by consultants and surgeons in training, at a tertiary
arthroplasty centre and performed survival analysis on the group
with revision as the endpoint.Aims
Patients and Methods
Heterotopic ossification (HO) occurs after arthroplasty, especially
total hip arthroplasty. In this study we describe the incidence,
evolution, morphology and clinical consequences of HO following
reverse shoulder arthroplasty. This is a single-centre retrospective study of 132 consecutive
patients who received a Delta III or Delta Xtend reverse total shoulder
arthroplasty between 2006 and 2013 for the treatment of cuff tear
arthropathy. There were 96 women and 36 men. Their mean age at the
time of surgery was 69 years (49 to 89) and the mean follow-up was
36 months (12 to 84). The incidence, evolution, morphology and clinical
consequences of HO using the Constant-Murley score (CS) were analysed.
A modified Brooker classification of HO of the hip was used.Aims
Patients and Methods
The early failure and revision of bimodular primary
total hip arthroplasty prostheses requires the identification of the
risk factors for material loss and wear at the taper junctions through
taper wear analysis. Deviations in taper geometries between revised
and pristine modular neck tapers were determined using high resolution
tactile measurements. A new algorithm was developed and validated
to allow the quantitative analysis of material loss, complementing
the standard visual inspection currently used. The algorithm was applied to a sample of 27 retrievals ( Cite this article:
The purpose of this study was to investigate
whether a gender-specific high-flexion posterior-stabilised (PS)
total knee replacement (TKR) would offer advantages over a high-flex
PS TKR regarding range of movement (ROM), ‘feel’ of the knee, pain
and satisfaction, as well as during activity. A total of 24 female
patients with bilateral osteoarthritis entered this prospective,
blind randomised trial in which they received a high-flex PS TKR
in one knee and a gender-specific high-flexion PS TKR in the other
knee. At follow-up, patients were assessed clinically measuring
ROM, and questioned about pain, satisfaction and daily ‘feel’ of
each knee. Patients underwent gait analysis pre-operatively and
at one year, which yielded kinematic, kinetic and temporospatial
parameters indicative of knee function during gait. At final follow-up
we found no statistically significant differences in ROM (p = 0.82).
The median pain score was 0 (0 to 8) in both groups (p = 0.95).
The median satisfaction score was 9 (4 to 10) in the high-flex group
and 8 (0 to 10) in the gender-specific group (p = 0.98). The median
‘feel’ score was 9 (3 to 10) in the high-flex group and 8 (0 to
10) in the gender-specific group (p = 0.66). Gait analysis showed
no statistically significant differences between the two prosthetic
designs in any kinematic, kinetic or temporospatial parameters. Both designs produced good clinical results with
Rarely, the extent of a malignant bone tumour
may necessitate resection of the complete humerus to achieve adequate
oncological clearance. We present our experience with reconstruction
in such cases using a total humeral endoprosthesis (THER) in 20
patients (12 male and eight female) with a mean age of 22 years
(6 to 59). We assessed the complications, the oncological and functional
outcomes and implant survival. Surgery was performed between June
2001 and October 2009. The diagnosis included osteosarcoma in nine,
Ewing’s sarcoma in eight and chondrosarcoma in three. One patient
was lost to follow-up. The mean follow-up was 41 months (10 to 120)
for all patients and 56 months (25 to 120) in survivors. There were
five local recurrences (26.3%) and 11 patients were alive at time
of last follow-up, with overall survival for all patients being
52% (95% confidence interval (CI) 23.8 to 74) at five years. The
mean Musculoskeletal Tumor Society score for the survivors was 22
(73%; 16 to 23). The implant survival was 95% (95% CI 69.5 to 99.3)
at five years. The use of a THER in the treatment of malignant tumours of bone
is oncologically safe; it gives consistent and predictable results
with low rates of complication.
We report a case of spontaneous physeal growth arrest of the distal femur in a nine-year-old child with Ewing’s sarcoma of the proximal femur treated with chemotherapy and endoprosthetic replacement. Owing to the extent of disuse osteoporosis at the time of surgery, the entire intramedullary canal up to the distal femoral physis was filled with cement. Three years later, the femur remained at its pre-operative length of 19 cm. Pre-operative calculations of further growth failed to account for the growth arrest, and the initial expandable growing prosthesis inserted has been revised to a longer one in order to address the leg-length discrepancy. To our knowledge, this is the only reported case of distal femoral physeal growth arrest following cemented endoprosthetic replacement of the proximal femur.
A clinical and radiological study was conducted on 97 total hip replacements performed for congenital hip dislocation in 79 patients between 1989 and 1998 using a three-dimensional custom-made cementless stem. The mean age at operation was 48 years (17 to 72) and the mean follow-up was for 123 months (83 to 182). According to the Crowe classification, there were 37 class I, 28 class II, 13 class III and 19 class IV hips. The mean leg lengthening was 25 mm (5 to 58), the mean pre-operative femoral anteversion was 38.6° (2° to 86°) and the mean correction in the prosthetic neck was −23.6° (−71° to 13°). The mean Harris hip score improved from 58 (15 to 84) to 93 (40 to 100) points. A revision was required in six hips (6.2%). The overall survival rate was 89.5% (95% confidence interval 89.2 to 89.8) at 13 years when two hips were at risk. This custom-made cementless femoral component, which can be accommodated in the abnormal proximal femur and will correct the anteversion and frontal offset, provided good results without recourse to proximal femoral corrective osteotomy.
Endoprosthetic replacement of the pelvis is one of the most challenging types of limb-salvage surgery, with a high rate of complications. In an attempt to reduce this and build greater versatility into the reconstruction process, a new type of pelvic endoprosthesis was developed in 2003, based on the old McKee-Farrar prosthesis. This study reviews the outcomes in 27 patients who had an ice-cream cone pelvic prosthesis inserted at two different specialist bone tumour centres in the United Kingdom over the past six years. The indications for treatment included primary bone tumours in 19 patients and metastatic disease in two, and six implants were inserted following failure of a previous pelvic reconstruction. Most of the patients had a P2+P3 resection as classified by Enneking, and most had resection of the ilium above the sciatic notch. The mean age of the patients at operation was 49 years (13 to 81). Complications occurred in ten patients (37.0%), of which dislocation was the most common, affecting four patients (14.8%). A total of three patients (11.1%) developed a deep infection around the prosthesis but all were successfully controlled by early intervention and two patients (7.4%) developed a local recurrence, at the same time as widespread metastases appeared. In one patient the prosthesis was removed for severe pain. This method of treatment is still associated with high morbidity, but early results are promising. Complications are diminishing with increasing experience.
We report the use of the reverse shoulder prosthesis in the revision of a failed shoulder hemiarthroplasty in 19 shoulders in 18 patients (7 men, 11 women) with severe pain and loss of function. The primary procedure had been undertaken for glenohumeral arthritis associated with severe rotator cuff deficiency. Statistically significant improvements were seen in pain and functional outcome. After a mean follow-up of 44 months (24 to 89), mean forward flexion improved by 26.4° and mean abduction improved by 35°. There were six prosthesis-related complications in six shoulders (32%), five of which had severe bone loss of the glenoid, proximal humerus or both. Three shoulders (16%) had non-prosthesis related complications. The use of the reverse shoulder prosthesis provides improvement in pain and function for patients with failure of a hemiarthroplasty for glenohumeral arthritis and rotator cuff deficiency. However, high rates of complications were associated with glenoid and proximal humeral bone loss.
We studied 33 third generation, alumina ceramic-on-ceramic bearings retrieved from cementless total hip replacements after more than six months in situ. Wear volume was measured with a Roundtest machine, and acetabular orientation from the anteroposterior pelvic radiograph. The overall median early wear rate was 0.1 mm3/yr for the femoral heads, and 0.04 mm3/yr for the acetabular liners. We then excluded hips where the components had migrated. In this stable subgroup of 22 bearings, those with an acetabular anteversion of <
15° (seven femoral heads) had a median femoral head wear rate of 1.2 mm3/yr, compared with 0 mm3/yr for those with an anteversion of ≥15° (15 femoral heads, p <
0.001). Even under edge loading, wear volumes with ceramic-on-ceramic bearings are small in comparison to other bearing materials. Low acetabular anteversion is associated with greater wear.
Peri-prosthetic bone loss caused by stress shielding may be associated with aseptic loosening of femoral components. In order to increase primary stability and to reduce stress shielding, a three-dimensional, cementless individual femoral (Evolution K) component was manufactured using pre-operative CT scans. Using dual energy x-ray absorptiometry, peri-prosthetic bone density was measured in 43 patients, three months, six months, 3.6 and 4.6 years after surgery. At final follow-up there was a significant reduction in mean bone density in the proximal Gruen zones of −30.3% (zone 7) and −22.8% (zone 1). The density in the other zones declined by a mean of between −4% and −16%. We conclude that the manufacture of a three-dimensional, custom-made femoral component could not prevent a reduction in peri-prosthetic bone density.
We reviewed 39 patients with displaced three- and four-part fractures of the humerus. In 21 patients (group A) we had used an anatomical prosthesis for the humeral head and in 18 (group B) an implant designed for fractures. When followed up at a mean of 29.3 months after surgery the overall Constant score was 51.9 points; in group A it was 51.5 and in group B 52.4 points. The subjective satisfaction of the patients was assessed using a numerical rating scale and was similar in both groups. In group A complete healing of the tuberosities was found in 29% and 50% in group B. Partial integration was seen in 29% of group A and in only one patient in group B, while resorption was noted in 43% of group A and 44% of group B. The functional outcome was significantly better in patients with complete or partial healing of the tuberosities (p = 0.022). The specific trauma prosthesis did not lead to better healing of the tuberosities. The difference in clinical outcome obtained by the two designs did not reach statistical significance.
The use of a navigation system in musculoskeletal tumour surgery enables the integration of pre-operative CT and MRI images to generate a precise three-dimensional anatomical model of the site and the extent of the tumour. We carried out six consecutive resections of musculoskeletal tumour in five patients using an existing commercial computer navigation system. There were three women and two men with a mean age of 41 years (24 to 47). Reconstruction was performed using a tumour prosthesis in three lesions and a vascularised fibular graft in one. No reconstruction was needed in two cases. The mean follow-up was 6.9 months (3.5 to 10). The mean duration of surgery was 28 minutes (13 to 50). Examination of the resected specimens showed clear margins in all the tumour lesions and a resection that was exactly as planned.
We compared the results of 146 patients who received an anatomic modular knee fixed-bearing total knee replacement (TKR) in one knee and a low contact stress rotating platform mobile-bearing TKR in the other. There were 138 women and eight men with a mean age of 69.8 years (42 to 80). The mean follow-up was 13.2 years (11.0 to 14.5). The patients were assessed clinically and radiologically using the rating systems of the Hospital for Special Surgery and the Knee Society at three months, six months, one year, and annually thereafter. The assessment scores of both rating systems pre-operatively and at the final review did not show any statistically significant differences between the two designs of implant. In the anatomic modular knee group, one knee was revised because of aseptic loosening of the tibial component and one because of infection. In addition, three knees were revised because of wear of the polyethylene tibial bearing. In the low contact stress group, two knees were revised because of instability requiring exchange of the polyethylene insert and one because of infection. The radiological analysis found no statistical difference in the incidence of radiolucent lines at the final review (Student’s We found no evidence of the superiority of one design over the other at long-term follow-up.
When performing the Scandinavian Total Ankle Replacement (STAR), the positioning of the talar component and the selection of mobile-bearing thickness are critical. A biomechanical experiment was undertaken to establish the effects of these variables on the range of movement (ROM) of the ankle. Six cadaver ankles containing a specially-modified STAR prosthesis were subjected to ROM determination, under weight-bearing conditions, while monitoring the strain in the peri-ankle ligaments. Each specimen was tested with the talar component positions in neutral, as well as 3 and 6 mm of anterior and posterior displacement. The sequence was repeated with an anatomical bearing thickness, as well as at 2 mm reduced and increased thicknesses. The movement limits were defined as 10% strain in any ligament, bearing lift-off from the talar component or limitations of the hardware. Both anterior talar component displacement and bearing thickness reduction caused a decrease in plantar flexion, which was associated with bearing lift-off. With increased bearing thickness, posterior displacement of the talar component decreased plantar flexion, whereas anterior displacement decreased dorsiflexion.