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Orthopaedic Proceedings
Vol. 106-B, Issue SUPP_13 | Pages 1 - 1
17 Jun 2024
Ahluwalia R Lewis T Musbahi O Reichert I
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Background

Optimal management of displaced intra-articular calcaneal fractures remains controversial. The aim of this prospective cohort study was to compare the clinical and radiological outcomes of minimally invasive surgery (MIS) versus non-operative treatment in displaced intra-articular calcaneal fracture up to 2-years.

Methods

All displaced intra-articular calcaneal fractures between August 2014 and January 2019 that presented to a level 1 trauma centre were considered for inclusion. The decision to treat was made by a multidisciplinary meeting. Operative treatment protocol involved sinus tarsi approach or percutaneous reduction & internal fixation. Non-operative protocol involved symptomatic management with no attempt at closed reduction. All fractures were classified, and the MOXFQ/EQ-5D-5L scores were used to assess foot and ankle and general health-related quality of life outcomes respectively.


Orthopaedic Proceedings
Vol. 106-B, Issue SUPP_10 | Pages 6 - 6
23 May 2024
Lewis T Ray R Gordon D
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Background

There are many different procedures described for the correction of hallux valgus deformity. Minimally invasive surgery has become increasingly popular, with clinical and radiological outcomes comparable to traditional open osteotomy approaches. There is increasing interest in hallux valgus deformity correction using third-generation minimally invasive chevron akin osteotomy (MICA) technique.

Objective

To assess the radiographic correction and 2 year clinical outcomes of third-generation MICA using validated outcome measures.


Orthopaedic Proceedings
Vol. 104-B, Issue SUPP_12 | Pages 31 - 31
1 Dec 2022
Sheridan G Clesham K Greidanus NV Masri B Garbuz D Duncan CP Howard L
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To date, the literature has not yet revealed superiority of Minimally Invasive (MI) approaches over conventional techniques. We performed a systematic review to determine whether minimally invasive approaches are superior to conventional approaches in total hip arthroplasty for (1) clinical and (2) functional outcomes. We performed a meta-analysis of level 1 evidence to determine whether (3) minimally invasive approaches are superior to conventional approaches for clinical outcomes. All studies comparing MI approaches to conventional approaches were eligible for analysis. The PRISMA guidelines were adhered to throughout this study. Registries were searched using the following MeSH terms: ‘minimally invasive’, ‘muscle-sparing’, ‘THA’, ‘THR’, ‘hip arthroplasty’ and ‘hip replacement’. Locations searched included PubMed, the Cochrane Library, ClinicalTrials.gov, the EU clinical trials register and the International Clinical Trials Registry Platform (World Health Organisation). Twenty studies were identified. There were 1,282 MI THAs and 1,351 conventional THAs performed. (1). There was no difference between MI and conventional approaches for all clinical outcomes of relevance including all-cause revision (p=0.959), aseptic revision (p=0.894), instability (p=0.894), infection (p=0.669) and periprosthetic fracture (p=0.940). (2). There was also no difference in functional outcome at early or intermediate follow-up between the two groups (p=0.38). (3). In level I studies exclusively, random-effects meta-analysis demonstrated no difference in the rate of aseptic revision (p=0.461) between both groups. Intermuscular MI approaches are equivalent to conventional THA approaches when considering all-cause revision, aseptic revision, infection, dislocation, fracture rates and functional outcomes. Meta-analysis of level 1 evidence supports this claim


Background

Exebacase, an antistaphylococcal lysin in Phase 3 of development as a treatment for S. aureus bacteremia/right-sided endocarditis has demonstrated antibiofilm activity in vitro and has previously been used as salvage therapy in four patients with relapsing multidrug-resistant (MDR) S. epidermidis knee prosthetic joint infection (PJI) using a procedure called LysinDAIR (administration of the lysin during the performance of an arthroscopic DAIR).

Materials/methods

We performed a single center, exploratory, open-label prospective study using the LysinDAIR procedure in patients with chronic (inoculation >3 months prior to treatment) coagulase-negative staphylococci (CNS) PJI of the knee with two different clinical presentations and treatment paradigms. Cohort A: first episode of CNS knee PJI, for whom the LysinDAIR was followed by clindamycin + levofloxacin planned to be prescribed for three months and then stopped; and Cohort B: relapsing episodes of MDR CNS knee PJI for whom the LysinDAIR was followed by primary antimicrobial therapy for three months, followed by suppressive antimicrobial therapy (SAT). Exebacae susceptibility testing was performed before treatment for each patient. In agreement with the French Health authority, exebacase (2 to 3.5 total mg in 30–50 ml (∼0.067 – 0.075 mg/m) was administered directly into the joint during arthroscopy.


The Bone & Joint Journal
Vol. 103-B, Issue 12 | Pages 1791 - 1801
1 Dec 2021
Bhalekar RM Nargol ME Shyam N Nargol AVF Wells SR Collier R Pabbruwe M Joyce TJ Langton DJ

Aims

The aim of this study was to investigate whether wear and backside deformation of polyethylene (PE) tibial inserts may influence the cement cover of tibial trays of explanted total knee arthroplasties (TKAs).

Methods

At our retrieval centre, we measured changes in the wear and deformation of PE inserts using coordinate measuring machines and light microscopy. The amount of cement cover on the backside of tibial trays was quantified as a percentage of the total surface. The study involved data from the explanted fixed-bearing components of four widely used contemporary designs of TKA (Attune, NexGen, Press Fit Condylar (PFC), and Triathlon), revised for any indication, and we compared them with components that used previous generations of PE. Regression modelling was used to identify variables related to the amount of cement cover on the retrieved trays.


Orthopaedic Proceedings
Vol. 103-B, Issue SUPP_12 | Pages 10 - 10
1 Oct 2021
Zein A Elhalawany AS Ali M Cousins G
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Despite multiple published reviews, the optimum method of correction and stabilisation of Blount's disease remains controversial. The purpose of this study is to evaluate the clinical and radiological outcomes of acute correction of late-onset tibial vara by percutaneous proximal tibial osteotomy with circular external fixation using two simple rings. This technique was developed to minimise cost in a context of limited resources.

This study was conducted between 2016 and 2020. We retrospectively reviewed the clinical notes and radiographs of 30 patients (32tibiae) who had correction of late-onset tibia by proximal tibial osteotomy and Ilizarov external fixator. All cases were followed up to 2 years.

The mean proximal tibial angle was 65.7° (±7.8) preoperatively and 89.8° (±1.7) postoperatively. The mean mechanical axis deviation improved from 56.2 (±8.3) preoperatively to 2.8 (±1.6) mm postoperatively. The mean femoral-tibial shaft angle was changed from – 34.3° (±6.7) preoperatively to 5.7° (±2.8) after correction. Complications included overcorrection (9%) and pin tract infection (25%). At final follow up, all patients had full knee range of motion and normal function. All cases progressed to union and there were no cases of recurrence of deformity.

This simple procedure provides secure fixation allowing early weight bearing and early return to function. It can be used in the context of health care systems with limited resources. It has a relatively low complication rate. Our results suggest that acute correction and simple circular frame fixation is an excellent treatment choice for cases of late-onset tibia vara, especially in severe deformities.


Orthopaedic Proceedings
Vol. 103-B, Issue SUPP_10 | Pages 22 - 22
1 Aug 2021
Stamp G Bhargava K Malviya A
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Periacetabular osteotomy (PAO) has been established as an effective technique to treat symptomatic hip dysplasia in young patients. Its role in treating borderline dysplasia and acetabular retroversion is evolving.

The aim of this study was to:

Examine the prospectively collected outcomes following a minimally invasive PAO in a large cohort of patients

Compare the outcomes of patients with severe dysplasia, borderline dysplasia and acetabular retroversion.

This is a single-surgeon review of patients operated in a high-volume centre with prospectively collected data between 2013 and 2020, and minimal followup of six months. PAO was performed using a minimally invasive modified Smith Peterson approach. 387 patients were operated during the study period and 369 eligible patients included in the final analysis. Radiographic parameters were assessed by two authors (GS and KB) with interrater reliability for 25 patients of 84–95% (IntraClass Coefficient). Patient reported outcome measures (i-HOT 12, NAHS, UCLA and EQ-5D) were collected prospectively. Case note review was also performed to collate complication data and blood transfusion rates.

Radiological parameters improved significantly after surgery with Lateral centre-edge angle (LCEA) improving by 16.4 degrees and Acetabular index (AI) improved by 15.8 degrees.

Patient reported outcome measures showed significant improvement in post-op NAHS, iHOT and EQ5D at 2 years compared to pre-op scores (NAHS=30.45, iHOT=42, EQ5D=0.32, p=0.01). This significance is maintained over 2 years post procedure (p=0.001). There was no significant difference between the three groups (severe dysplasia, borderline dysplasia and acetabular retroversion).

Clinical outcomes showed an overall complication rate n=31, 8.3% (Major complication rate: n=3, 0.81%). Non-union rate: n=11, 2.96% of which 3 required fixation (0.81%). Hip arthroscopy post PAO: n=7, 1.9%. Conversion to THR: n=4, 1.1%. Blood transfusion requirement: n=46, 12.5%. No patient developed a major neurovascular injury.

In this large single-centre study, patients had radiological and reported outcome improvements following surgery. Overall, there was a low complication rate, providing further evidence of the safety and efficacy of PAO for ameliorating pain and long-lasting results in the management of symptomatic hip dysplasia.


Orthopaedic Proceedings
Vol. 103-B, Issue SUPP_4 | Pages 5 - 5
1 Mar 2021
Kumar G Debuka E
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Increasing incidence of osteoporosis, obesity and an aging population have led to an increase in low energy hip fractures in the elderly. Perceived lower blood loss and lower surgical time, media coverage of minimal invasive surgery and patient expectations unsurprisingly have led to a trend towards intramedullary devices for fixation of extracapsular hip fractures. This is contrary to the Cochrane review of random controlled trials of intramedullary vs extramedullary implants which continues recommends the use of a sliding hip screw (SHS) over other devices. Furthermore, despite published literature of minimally invasive surgery (MIS) of SHS citing benefits such as reduced soft tissue trauma, smaller scar, faster recovery, reduced blood loss, reduced analgesia needs; the uptake of these approaches has been poor. We describe a novel technique one which remains minimally invasive, that not only has a simple learning curve but easily reproducible results. All patients who underwent MIS SHS fixation of extracapsular fractures were included in this study. Technique is shown in Figure 1. We collated data on all intertrochanteric hip fractures that were treated by a single surgeon series during period Jan 2014 to July 2015. Data was collected from electronic patient records and radiographs from Picture Archiving and Communication System (PACS). Surgical time, fluoroscopy time, blood loss, surgical incision length, post-operative transfusion, Tip Apex Distance (TAD) were analyzed. There were 10 patients in this study. All fractures were Orthopaedic Trauma Association (OTA) type A1 or A2. Median surgical time was 36 minutes (25–54). Mean fluoroscopy time was similar to standard incision sliding hip screw fixation. Blood loss estimation with MIS SHS can be undertaken safely and expeditiously for extracapsular hip fractures.


Obesity is an increasing public health concern associated with increased perioperative complications and expense in lumbar spine fusions. While open and mini-open fusions such as transforaminal lumbar interbody fusion (TLIF) and minimally invasive TLIF (MIS-TLIF) are more challenging in obese patients, new MIS procedures like oblique lateral lumbar interbody fusion (OLLIF) may improve perioperative outcomes in obese patients relative to TLIF and MIS-TLIF.

The purpose of this study is to determine the effects of obesity on perioperative outcomes in OLLIF, MIS-TLIF, and TLIF. This is a retrospective cohort study.

We included patients who underwent OLLIF, MIS-TLIF, or TLIF on three or fewer spinal levels at a single Minnesota hospital after conservative therapy had failed. Indications included in this study were degenerative disc disease, spondylolisthesis, spondylosis, herniation, stenosis, and scoliosis. We measured demographic information, body mass index (BMI), surgery time, blood loss, and hospital stay. We performed summary statistics to compare perioperative outcomes in MIS-TLIF, OLLIF, and TLIF. We performed multivariate regression to determine the effects of BMI on perioperative outcomes controlling for demographics and number of levels on which surgeries were operated.

OLLIF significantly reduces surgery time, blood loss, and hospital stay compared to MIS-TLIF, and TLIF for all levels. MIS-TLIF and TLIF do not differ significantly except for a slight reduction in hospital stay for two-level procedures. On multivariate analysis, a one-point increase in BMI increased surgery time by 0.56 ± 0.47 minutes (p = 0.24) in the OLLIF group, by 2.8 ± 1.43 minutes (p = 0.06) in the MIS-TLIF group, and by 1.7 ± 0.43 minutes (p < 0.001) in the TLIF group. BMI has positive effects on blood loss for TLIF (p < 0.001) but not for OLLIF (p = 0.68) or MIS-TLIF (p = 0.67). BMI does not have significant effects on length of hospital stay for any procedure.

Obesity is associated with increased surgery time and blood loss in TLIF and with increased surgery time in MIS-TLIF. Increased surgery time may be associated with increased perioperative complications and cost. In OLLIF, BMI does not affect perioperative outcomes. Therefore, OLLIF may reduce the disparity in outcomes and cost between obese and non-obese patients.


Orthopaedic Proceedings
Vol. 102-B, Issue SUPP_1 | Pages 34 - 34
1 Feb 2020
Kim Y Pour AE Lazennec J
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Purpose

Minimally invasive anterolateral approach (ALA) for total hip arthroplasty (THA) has gained popularity in recent years as better postoperative functional recovery and lower risk of postoperative dislocation are claimed. However, difficulties for femur exposure and intraoperative complications during femoral canal preparation and component placement have been reported. This study analyzes the anatomical factors likely to be related with intraoperative complications and the difficulties of access noted by the surgeons through a modified minimally invasive ALA. The aim is to define the profile for patient at risk of intraoperative complications during minimally invasive ALA.

Methods

We retrospectively included 310 consecutive patients (100 males, 210 females) who had primary unilateral THA using the same technique in all cases. The approach was performed between the tensor fascia lata and the gluteus medius and minimus, without incising or detaching muscles and tendons. Posterior translation was combined to external rotation for proximal femur exposure (Fig. 1). All patients were reviewed clinically and radiologically. For the radiological evaluation, all patients underwent pre- and postoperative standing and sitting full-body EOS acquisitions. Pelvic [Sacral slope, Pelvic incidence (PI), Anterior pelvic plane angle] and femoral parameters were measured preoperatively. We assessed all intraoperative and postoperative complications for femoral preparation and implantation. Intraoperative complications included the femoral fractures and difficulties for femoral exposure (limitations for exposure and lateralization of the proximal femur). The patients were divided into two groups: patients with or without intraoperative complications.


Orthopaedic Proceedings
Vol. 102-B, Issue SUPP_1 | Pages 123 - 123
1 Feb 2020
Maeda A Tsuchida M Kusaba A Kondo S
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The anterolateral MIS-THA approach can be divided into the Modified Watson-Jones approach (MWJ) performed in the lateral position and the Anterolateral Supine method (ALS) performed in the supine position. Femoral preparation is flexible in stem selection in the MWJ method. On the other hand, the ALS method is more stable for placement on the acetabular implant.

Now we introduce novel anterolateral MIS approach named AL60, it makes use of the merits of both MWJ and ALS methods.

Technique

The patient is fixed at 30 degrees on the dorsal side from lateral position. That is 60 degrees on the half side from the horizontal plane, and the platform of the operating table is removed just as in the MWJ method. During surgery, the pelvis is fixed by the posterior support, and the stability of the pelvis is very good. Also, if the inclination is accurate at 30 degrees, by holding the holder parallel to the operating table when inserting the cup, the cup is theoretically inserted at Anatomical anteversion 30 degrees. The intraoperative field of view is also visible to the assistant due to the semi-lateral position.

Femoral preparation is easier than the MWJ method because the affected limbs have fallen to the dorsal side already.

Discussion

Since March 2017 to the end of August 2018, the AL60 method was used for 207 primary THA. There were no dislocations or fractures and any other complications.

Full weight bearing was possible from the next day.

The AL60 method has stability of the ALS method for acetabular preparation and the operability of the MWJ method for femoral preparation.

Therefore, it can be said that new AL60 approach method makes use of the merits of both MWJ and ALS methods.


The Bone & Joint Journal
Vol. 101-B, Issue 12 | Pages 1469 - 1471
1 Dec 2019
Haddad FS Horriat S


Orthopaedic Proceedings
Vol. 101-B, Issue SUPP_13 | Pages 12 - 12
1 Nov 2019
Palo N Chandel SS Borgohain B Patel MK Das DS Srivastav T
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Acromioclavicular joint is an integral component of Shoulder Complex and common site of injury particularly for athletes involved in sports such as Football, Cricket, Rugby and Shotput. Acromioclavicular Injuries are often neglected and goes untreated especially in low demand patients. Classic surgical techniques are associated with high complication rates. This is a prospective study from 2015–2017 wherein 32 patients with Acute grade 3, 4, 5, 6 Acromioclavicular joint dislocations, were operated with Minimally Invasive Double Tunnel Anatomical Coraco-clavicular Ligament Reconstruction (DT-ACCLR) with Tightrope Suspensory fixation. Clinical Outcomes were evaluated with Visual Analog Scale, Constant functional scale, Start of Movement, Return to Work, Satisfaction index and Coraco-clavicular distance over 12 months. Mean follow-up was 14 ± 3.8 months. Visual analog scale and Constant scores revealed significant advancements 0 ± 0.5 (range, 0–2) and 95 ± 3 (range, 92–98) scores at 12 months respectively. The coraco-clavicular distance significantly reduced from 23 ± 2.4 mm to 8 ± 0.5 mm. Mean return to work by 7 days. 98.6% patients were satisfied with surgical results. We conclude that DT-ACCLR is simple and creative surgical technique which provides stable, reliable and painless AC joint. The patients can move the shoulder same day and return to Work by 5–7days and Sports 3–4 weeks


Orthopaedic Proceedings
Vol. 101-B, Issue SUPP_13 | Pages 3 - 3
1 Nov 2019
Papachristos IV Dalal RB Rachha R
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Short scarf osteotomy (SSO) retains the versatility of standard scarf in treating moderate and severe hallux valgus deformity with the added benefit of less invasiveness translated into less soft-tissue stripping, reduced exposure, less metalwork, less operative time and reduced cost. We present our medium-term clinical, radiographic and patient satisfaction results.

All patients who underwent SSO between January 2015 and December 2017 were eligible (98). Exclusion criteria were: follow up less than a year, additional 1st ray procedures, inflammatory arthropathy, infection, peripheral vascular disease and hallux rigidus. Eighty-four patients (94 feet) were included: 80 females / 4 males with average age of 51-year-old (24–81). Minimum follow up was 12 months (12–28). Weight-bearing x-rays and AOFAS score were compared pre- and postoperatively. Non-parametric Mann-Whitney U test assessed statistical significance of our results.

Hallux valgus angle (HVA) improved from preoperative mean of 30.8° (17.4°–46.8°) to 12° (4°–30°) postoperatively (p=0.0001). Intermetatarsal angle (IMA) improved from preoperative mean of 15.1° (10.3°–21.1°) to 7.1° (4°–15.1°) postoperatively (p=0.0001). Average sesamoid coverage according to Reynold's tibial sesamoid position improved from average grade 2.18 (1–3) to 0.57 (0–2) (p=0.0001). Average AOFAS score improved from 51.26 (32–88) to 91.1 (72–100) (p=0.0001). Ninety percent of patients were satisfied and 83% wound recommend the surgery. No troughing phenomenon or fractures. Four overcorrections were found 3 of which did not require surgery. One recurrence at 18 months was treated with standard scarf.

We believe that this technique offers a safer, quicker and equally versatile way of dealing with Hallux Valgus.


Orthopaedic Proceedings
Vol. 101-B, Issue SUPP_6 | Pages 3 - 3
1 May 2019
Thiagarajah S Verhaegen J Balijepalli P Bingham J Grammatopoulos G Witt J
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Introduction

The periacetabular osteotomy (PAO) improves hip joint mechanics in patients with symptomatic dysplasia. As a consequence of the multi-planar acetabular re-orientation, the course of the iliopsoas tendon over the hip may be affected, potentially resulting in iliopsoas tendon-related pain. At present, little information regarding the incidence of iliopsoas-related pathology following PAO exists.

We aimed to identify the incidence of iliopsoas-related pain following PAO. Secondarily, we aimed to identify any risk factors associated with this pathology.

Methods

We retrospectively reviewed the PAO's performed from 2014–2017, for symptomatic dysplasia in our unit (single-surgeon, minimum 1-year follow-up). All patients with adequate pelvic radiographs were included. Radiographic parameters of dysplasia were measured from pre- and post-operative AP pelvic radiographs using a validated software (SHIPS)1. The degree of pubis displacement was classified according to our novel system. Cases were defined as those with evidence of iliopsoas-related pain post PAO (positive response to iliopsoas tendon-sheath steroid/local anaesthetic injection).


INTRODUCTION

The primary goal of THA or TKA is to relieve pain and restore mobility. The success is determined by the longevity of prostheses and early return to routine activities, such as driving. With enhanced recovery regimens, patients are being discharged within 24–48hrs post-op.. The aim of this study was to determine when our patients returned to driving after anterior hip replacements and patient specific knee replacements.

METHODOLOGY

This study included 207 soft tissue sparing anterior bikini THA and 146 patient specific instrumented (PSI) TKAs between Feb 2017 and March 2018. All patients included drove before surgery. Non-drivers were excluded. A detailed questionnaire was sent to all patients 3 to 6 weeks after surgery to record their driving status. 50 patients were randomly selected to assess flexion at the hip, knee, and ankle joints whilst seated in the driver's seat of their vehicle.


Orthopaedic Proceedings
Vol. 101-B, Issue SUPP_5 | Pages 144 - 144
1 Apr 2019
Prasad KSRK Kumar R Sharma A Karras K
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Background. Stress fractures at tracker after computer navigated total knee replacement are rare. Periprosthetic fracture after Minimally Invasive Plate Osteosynthesis (MIPO) of stress fracture through femoral tracker is unique in orthopaedic literature. We are reporting this unique presentation of periprosthetic fractures after MIPO for stress fracture involving femoral pin site track in computer assisted total knee arthroplasty, treated by reconstruction nail (PFNA). Methods. A 75-year old female, who had computer navigated right total knee replacement, was admitted 6 weeks later with increasing pain over distal thigh for 3 weeks without trauma. Prior to onset of pain, she achieved a range of movements of 0–105 degrees. Perioperative radiographs did not suggest obvious osteoporosis, pre-existent benign or malignant lesion, or fracture. Radiographs demonstrated transverse fracture of distal third of femur through pin site track. We fixed the fracture with 11-hole combihole locking plate by MIPO technique. Eight weeks later, she was readmitted with periprosthetic fracture through screw hole at the tip of MIPO Plate and treated by Reconstruction Nail (PFNA), removal of locking screws and refixation of intermediate segment with unicortical locking screws. Then she was protected with plaster cylinder for 4 weeks and hinged brace for 2 months. Results. Retrograde nail for navigation pin site stress fracture entails intraarticular approach with attendant risks including scatches to prosthesis and joint infection. So we opted to fix by MIPO technique. Periprosthetic fracture at the top of MIPO merits fixation with antegrade nail in conjunction with conversion of screws in the proximal part of the plate to unicortical locking screws. Overlap of at least 3cms offers biomechanical superiority. She made an uneventful recovery and was started on osteoporosis treatment, pending DEXA scan. Conclusion. Reconstruction Nail (PFNA), refixation of intermediate segment with unicortical locking screws constitutes a logical management option for the unique periprosthetic fracture after MIPO of stress fracture involving femoral pin site track in computer assisted total knee replacement


Orthopaedic Proceedings
Vol. 101-B, Issue SUPP_5 | Pages 40 - 40
1 Apr 2019
Elkabbani M El-Sayed MA Tarabichi S Malkawi AS Schulte M
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Aim

The objective of this study was to evaluate the intermediate term clinical and radiological results of a new short stem hip implant.

Methods

In 20 consecutive patients suffering from osteoarthritis with 25 affected hip joints (five cases were bilateral), the clinical and radiological results of 25 hip arthroplasties performed in one hospital between October 2009 and May 2014 through a minimally invasive anterolateral approach using a cementless short stem prosthesis type Aida and a cementless cup type Ecofit with a ceramic on ceramic pairing were evaluated prospectively. The median age of patients at time of surgery was 60 years (range, 42–71 years), 15 male (4 were bilateral) and 5 female patients (one was bilateral) were included in the study. The median clinical follow up was 30 months (range, 2–88 months), and the median radiological follow up was 30 months (range, 2–88 months).


Orthopaedic Proceedings
Vol. 101-B, Issue SUPP_4 | Pages 74 - 74
1 Apr 2019
Giles J Broden C Tempelaere C Rodriguez-Y-Baena F
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PURPOSE

To validate the efficacy and accuracy of a novel patient specific guide (PSG) and instrumentation system that enables minimally invasive (MI) short stemmed total shoulder arthroplasty (TSA).

MATERIALS AND METHODS

Using Amirthanayagam et al.'s (2017) MI posterior approach reduces incision size and eliminates subscapular transection; however, it precludes glenohumeral dislocation and the use of traditional PSGs and instruments. Therefore, we developed a PSG that guides trans-glenohumeral drilling which simultaneously creates a humeral guide tunnel/working channel and glenoid guide hole by locking the bones together in a pre-operatively planned pose and drilling using a c-shaped drill guide (Figure 1). To implant an Affinis Short TSA system (Mathys GmbH), novel MI instruments were developed (Figure 2) for: humeral head resection, glenoid reaming, glenoid peg hole drilling, impaction of cruciform shaped humeral bone compactors, and impaction of a short humeral stem and ceramic head.

The full MI procedure and instrument system was evaluated in six cadaveric shoulders with osteoarthritis. Accuracy was assessed throughout the procedure: 1) PSG physical registration accuracy, 2) guide hole accuracy, 3) implant placement accuracy. These conditions were assessed using an Optotrak Certus tracking camera (NDI, Waterloo, CA) with comparisons made to the pre-operative plan using a registration process (Besl and McKay, 1992).


Orthopaedic Proceedings
Vol. 101-B, Issue SUPP_2 | Pages 14 - 14
1 Jan 2019
Warren JP Coe R Sikora S Miles DE Beales P Wilcox RK
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The purpose of this study was to develop a novel, minimally invasive therapy for nucleus pulposus augmentation without the need for major surgical incision.

Two optimum patented self-assembling peptides based on natural amino acids were mixed with glycosaminoglycans (GAGs) to form reversible, tunable hydrogels that mimic the vital biological osmotic pumping action and aid in swelling pressure of the intervertebral disc (IVD). Separate peptide and GAG solutions can be switched from fluid to gel upon mixing inside the body. The gels were analysed using a series of complementary techniques (FTIR, TEM & rheometry) to determine their cross-length scale structure and properties. Approaches to developing a clinical product were then developed including the incorporation of a fluorescent probe and a CT contrast agents to aid visualization of the gels, and a semi-automatic syringe driver rig, incorporating a pressure sensor, for the delivery of the solutions into the intervertebral discs. The efficacy of the procedure in restoring disc height and biomechanics was examined using chemically degenerated bovine caudal samples.

It was found the presence of the GAGs stabilized the peptides forming stiffer gels, even upon injection through a long (∼10cm) small gauge needle. The injected gels were easily visualized post injection by microCT and by eye during dissection under visible and UV light. It was also noted that following injection, the disc height of the degenerated samples was restored to a similar level of that observed for native discs.

A hydrogel has been developed that is injected through a narrow bore needle using a semi-automatic delivery rig and forms a self-assembled gel in situ which has shown to restore the disc height. Further tests are now underway to examine their biomechanical performance across more physiological time periods.