Mechanical ankle instability is elicited through examination and imaging. A subset of patients however report “functional” instability ie/ instability without objective radiological evidence. Little research compares operative outcomes between these groups. We hypothesised patients with “mechanical instability” were more likely to benefit from operative intervention than those with “functional instability”.

This was a single centre, retrospective case note review of prospectively collected data. Inclusion criteria: over six months of symptoms, failed conservative management, surgical stabilisation between 2016–2018. Data collected: demographics, operative procedure, preoperative and postoperative PROMs.

Nineteen patients were included. All had preoperative MRIs determining ligamentous involvement. Nine had radiological evidence of instability, eight had negative radiographs. Two were excluded due to no intraoperative radiographs.

There was no statistical difference in preoperative MOxFQ scores between the groups (p=0.2039). Preoperative EQ5D-TTO scores were statistically different (mean mechanical 0.58 vs functional 0.26, p=0.0162) but not EQ5D-VAS scores (mean mechanical 77 vs functional 53, p=0.0806).

Mechanical group's preoperative, 26 and 52 week scores respectively: Mean MOxFQ= 57.88, 22.13, 18.5. Mean EQ5D-TTO= 0.58, 0.78, 0.84. EQ5D-VAS= 77, 82, 82.5.

Functional group's preoperative, 26 and 52 week scores respectively: Mean MOxFQ= 71.87, 37.75, 23. Mean EQ5D-TTO 0.26, 0.63, 0.76. EQ5D-VAS 53, 80, 88.

This trend of improvement in PROMs was not reflected in patient satisfaction scores. 75% of respondents in the functional group reported dissatisfaction at 26 weeks versus no dissatisfaction in the mechanical group. We should consider counselling patients accordingly when offering surgery.

Arthritis of the mid-foot is a common presentation to the foot and ankle clinic, resulting from primary (idiopathic), post-traumatic, or inflammatory joint degeneration. Treatment in the initial stages is conservative, with midfoot fusion regarded as the operative treatment of choice; however there is a paucity of comparative and patient reported data regarding outcomes.

Patient reported outcome measures (PROMS), were prospectively collected from October-2015 to March-2018. Diagnoses were confirmed with image guided injection and initial management was conservative. In total, 66 patients were managed conservatively and 40 treated with mid-foot fusion. MOxFQ (Manchester Oxford Foot Questionnaire) and EQ-5D-3L (Euroqual) PROMS were collected pre-operatively, at 26 weeks and at 52 weeks.

In the operatively managed group, the female:male ratio was 5.7:1, with a mean age of 61 (range 24–80), while in the conservatively managed group, the ratio was 2.1:1 with mean age 63 (range 29–86).

In the surgically managed group, 88.2% of patients reported improvement in symptoms at 26 weeks and 88.9% at 52 weeks. This was greater than the conservatively managed group, in which 40.6% reported improvement at 26 weeks and 33.3% at 52 weeks. Mean MOxFQ improvement in the surgically managed group was +30.7 and +33.9 at 26 and 52 weeks respectively, and in the conservative group, +9.4 and +4.3, at 26 and 52 weeks. Similarly, favourable surgical outcomes were reported across all domains of EQ-5D-3L.

This study has highlighted excellent early outcomes after surgical treatment and may represent promise for those patients for whom conservative management fails.

This study aimed to ascertain whether stabilising only the AITFL is enough to prevent talar shift, and to test a simple, novel technique to reconstruct the AITFL.

Twelve cadavers were used. Talar shift was measured following: 1- no ligaments cut; 2- entire deltoid ligament division; 3- group A (5 specimens) PITFL cut whilst group B (7 specimens) AITFL cut; 4- group A had AITFL divided whilst group B had the PITFL cut. Reconstruction of the AITFL was performed using part of the superior extensor retinaculum as a local flap. Measurement of talar shift was then repeated.

With no ligaments divided, mean talar shift was 0.8mm for group A and 0.7mm for group B. When the deltoid ligament was divided, mean talar shift for group A was 4.8mm compared to 4.7mm in group B (P=1.00). The mean shift in group A after PITFL division was 6.0mm, increasing the talar shift by an average of 1.2mm. In group B after AITFL division mean talar shift was 8.3mm (P=0.06), increasing talar shift by an average of 3.6 mm. After division of the second tibiofibular ligament, mean talar shift in group A measured 10.0mm and in group B was 10.9mm(P=0.29).

Three times more talar shift occurred after the AIFTL was divided compared to the PITFL. Repairing just the PITFL (for example by fixation of the posterior malleolus avulsion fracture) may not adequately prevent talar shift while reconstruction of the AITFL potentially restores ankle stability.

Adequate perpendicular access to the posterolateral talar dome for osteochondral defect repair is difficult to achieve and a number of different surgical approaches have been described. This cadaveric study examined the exposure available from various approaches to help guide pre-operative surgical planning.

Four surgical approaches were performed in a step-wise manner on 9 Thiel-embalmed cadavers; anterolateral approach with arthrotomy, anterolateral approach with anterior talo-fibular ligament (ATFL) release, anterolateral approach with antero-lateral tibial osteotomy, and anterolateral approach with lateral malleolus osteotomy. The furthest distance posteriorly which allowed perpendicular access with a 2mm k-wire to the lateral surface of the talar dome was measured from the anterior aspect of the talar dome.

The mean antero-posterior diameter of the lateral talar domes included in this study was 45.1mm. An anterolateral approach to the ankle with arthrotomy provided a mean exposure of the anterior 1/3rd of the lateral talar dome. ATFL release increased this to 43.2%. A lateral malleolus osteotomy provided superior exposure (81.5% vs 58.8%) compared to an anterolateral tibial osteotomy.

Only the anterior half of the lateral border of the talar dome could be accessed with an anterolateral approach without osteotomy. A fibular osteotomy provided best exposure to the posterolateral aspect of the talar dome and is recommended for lesions affecting the posterior half of the lateral talar dome.

There is debate whether a home run screw (medial cuneiform to 2nd metatarsal base) combined with k-wire fixation of 4th & 5th rays is sufficient to stabilise Lisfrance injuries or if fixation of the 3rd ray is also required. Unlike the 2nd, 4th and 5th TMTJ, stabilisation of the 3rd requires either intra-articular screw or a cross joint plate which both risk causing chondrolysis and/or OA.

Using 8 Theil embalmed specimens, measurements of TMTJ dorsal displacement at each ray (1st to 5th) and 1st – 2nd metatarsal gaping were made during simulated weight bearing with sequential ligamentous injury and stabilisation to determine the contribution of anatomical structures and fixation to stability.

At baseline mean dorsal TMTJ displacement of the intact specimens during simulated weight bearing (mm) was: 1st: 0.14, 2nd: 0.1, 3rd:0, 4th: 0, 5th: 0.14. The 1st-2nd IM Gap was 0mm. After transection of the Lisfranc ligament only, there was 1st-2nd intermetatarsal gaping (mean 4.5mm), but no increased dorsal displacement. After additional transection of all the TMTJ ligaments dorsal displacement increased at all joints (1st: 4.5, 2nd: 5.1, 3rd: 3.6, 4th: 2, 5th: 1.3). Stabilisation with the home run screw and 4th and 5th ray k-wires virtually eliminated all displacement. Further transection of the 3rd/4th inter-metatarsal ligaments increased mean dorsal displacement of the 3rd ray to 2.5mm. K-wire fixation of the 3rd ray completely eliminated dorsal displacement.

The results suggest that stabilising the 2nd and 4/5th TMTJs will stabilise the 3rd if the inter-metatarsal ligaments are intact. Thus 3rd TMTJ stability should be checked after stabilising the 2nd and 4/5th. Provided the intermetatarsal ligaments (3rd-4th) are intact the 3rd ray does not need to be stabilised routinely.

Shoulder arthroplasty is the treatment of choice for a range of degenerative diseases. However, long term follow-up suggests almost half of patients graded their treatment as unsatisfactory. Component malalignment is thought the most likely cause. The anterior anatomical neck is used as a reference for the osteotomy. The objective of the study was to analyse the cartilage/metaphyseal interface to identify reference points that may recover version accurately.

Twenty-four humeri were scanned using a Microscribe digitiser and surface laser scanner. Modelling software was used to analyse the Cartilage/metaphyseal interface. The retroversion angle was calculated for the normal geometry and for the standard osteotomy. An ideal osteotomy plane was then created for each specimen and the distance from the cartilage/metaphyseal interface determined, identifying points of least deviation. The reference points were used to simulate a new osteotomy for which retroversion was calculated. The novel osteotomy and traditional osteotomy were compared to the normal geometry.

The mean retroversion for the normal geometry was 18.5±9.0 degrees. The mean retroversion for the traditional osteotomy technique was 29.5±10.7 degrees, significantly different from the original (p<0.001). The mean retroversion using the novel osteotomy was 18.9±8.9 degrees and similar to the normal geometry (p=0.528).

The traditional osteotomy resulted in a mean increase in retroversion of 38%. The increase in version may result in eccentric loading at the glenoid and alter rotator cuff balance. The novel osteotomy resulted in more accurate recovery of head geometry and may improve clinical outcome.

The anterior portion of the anatomical neck is used as a reference for the osteotomy in shoulder arthroplasty. Resection at this level is thought to remove a segment of a sphere which can accurately be replaced with a prosthetic implant. The objective of the study was to analyse the cartilage/metaphyseal interface relative to an ideal osteotomy plane to define points of reference the may recover retroversion accurately. Data were collected from 24 humeri using a novel technique, combining data acquired using a Microscribe digitiser and surface laser scanner. Rhinocerus NURBS modelling software was used to analyse the Cartilage/metaphyseal interface. The retroversion angle was calculated for the normal geometry and for the standard osteotomy along the anterior cartilage/metaphyseal interface. An ideal osteotomy plane was then created for each specimen and the perpendicular distance from the cartilage/metaphyseal interface was determined, identifying points of least deviation. The reference points were used to simulate a new osteotomy for which retroversion was calculated. Paired t-tests were used to compare the novel osteotomy and traditional osteotomy to the normal geometry. The mean retroversion for the normal geometry was 18.5±9.0 degrees. The mean retroversion for the traditional osteotomy technique was 29.5±10.7 degrees, significantly different from the original (p< 0.001). The mean retroversion using the novel osteotomy was 18.9±8.9 degrees and similar to the normal geometry (p=0.528). The traditional osteotomy resulted in a mean increase in retroversion of 38%. The increase in version may result in eccentric load on the glenoid, an alteration to the rotator cuff balance and poor clinical outcome. The novel osteotomy based on points identified around the cartilage/metaphyseal interface that deviated least from an ideal osteotomy plane resulted in more accurate recovery of head geometry. The novel technique may improve clinical outcome. Further investigation is warranted.

Introduction: Ankle Arthroplasty is an alternative to arthrodesis for patients with disabling ankle arthritis. It aims to remove pain and preserve joint motion. We aimed to review the outcome of all total ankle replacements carried out in our institution between 2002 and 2006.

Materials and Methods: We retrospectively reviewed the results of all patients who underwent the Agility ankle replacement performed by a single surgeon. Case notes and radiographs were reviewed and outcome assessment included standardised questionnaires.

Results: 30 arthroplasties were performed in 30 consecutive patient. 11 males, 19 females, Pre operative diagnosis was rheumatoid arthritis (16), primary osteoarthritis (12) and post-traumatic osteoarthritis (2) with a mean age of 61.8 yrs. 8 patients required an additional procedure at the time of arthroplasty : tendoachilles lengthening (6); Calcaneal osteotomy (2); triple arthrodesis (2); tip post reconstruction (1). Intra operative technical complications included: Fracture of medial malleolus (3); nerve injury (3); tendon injury (1). 8 patients had wound problems: Delayed healing > 3/52 (8); Superficial infection (2); Deep infection (2). 1 patient had delayed union of the syndesmosis (> 6 months) and 6 had non-union (> 12 months).

After a mean follow up of 3.2 years 2 patients had died and 9 patients had required further surgery: Implant removal for infection (1); Talar revision for loosening (1); Re-fusion of the syndemosis (4); Removal of syndesmosis screws (3); Calcaneal osteotomy for valgus hindfoot (1).

Discussion: We found a high rate of complications which may be related to the surgeons learning curve, although some are specific to the design of implant which requires a tibio-fibular fusion.

Conclusion: The first 30 agility ankle replacements performed in our centre demonstrates several potential complications and shows that there is often a need for subsequent surgery. Short term survivorship of the implant is acceptable and long term review is required.

Introduction: The osteotomy in shoulder arthroplasty is based on the assumption that the resected articular segment corresponds to a segment of a sphere oriented, identically, in inclination and retroversion to the original humeral head(1). A previous report has suggested that the traditional osteotomy technique performed along the antero-superior part of the anatomical neck does not accurately replicate inclination and retroversion of the humeral head(2). We hypothesize that a simulated osteotomy performed along the antero-inferior anatomical neck resects a portion of the humeral head similarly oriented to the original head in terms of inclination and retroversion, and, more closely matches head diameter and radius of curvature when compared to the traditional osteotomy approach.

Methods: Twenty-eight fresh frozen cadaveric full arms were dissected free of soft tissue. Lines, points and surfaces were identified on each specimen. A Microscribe digitizer was used to digitize the points and lines. Data were imported into Rhinoceros NURBS modelling software and graphically modelled. The following parameters were used to describe the humeral head geometry: the longitudinal and axial radii of curvature (RoC) of the articular surface; the inclination angle (ƒÑ) and retroversion angle (ƒÒ). To simulate the traditional osteotomy, a plane was constructed using points at the anterior portion of the anatomical neck. The new osteotomy plane was formed using points at the antero-inferior anatomical neck. Paired Student’s t-test was used to compare techniques.

Results: No differences were found between the axial RoC of the resected segment for the new technique (22.5mm) when compared to the original head (22.5mm); a difference was found for the old osteotomy technique (23.0mm). In the coronal plane, no differences were found for the RoC of both the new and traditional techniques when compared to the original head. The axial and coronal diameters of the osteotomized surface were significantly different for both techniques. However, the mean difference between the axial and coronal diameters for the new technique was 2.4mm and, for the traditional technique, 3.2mm. Significant differences in retroversion of the resected surface were found when the new osteotomy technique (24.5deg) and traditional technique (40.5deg) were compared to the original head (29.0deg). Further, significant differences in inclination were found, when the new osteotomy technique (129.5deg) and traditional technique (132.1deg) were compared to the original head inclination (136.9deg).

Discussion: This study found that an osteotomy performed along the anteroinferior part of the anatomical neck removes an articular segment that is more spherical than a segment removed by the traditional osteotomy approach. Although significantly different from the original head, the retroversion associated with the new technique more closely matches the anatomy when compared to the traditional technique. The new osteotomy decreased the inclination angle by 7 degrees. This finding is unlikely to be clinically relevant. Cadaveric studies will reveal the accuracy of an anatomical reconstruction using the novel osteotomy approach.

Introduction: Successful shoulder arthroplasty is based on restoration of the individual’s proximal humeral morphology with a precise osteotomy of the humeral head at the level of the anatomical neck. The objective of this study was to determine the geometry of the articular portion of the humeral head in contact with the glenoid in the neutral position and compare the orientation to the geometry of the humeral head determined using the cartilage/calcar interface of the anatomical neck.

Methods: An intact rotator cuff and joint capsule were exposed for six cadaveric full arms. Precision perspex reference cubes were attached to the greater tuberosity of the humerus and to the coracoid process of the scapula on each specimen. Each shoulder was mounted in a custom built jig with the arm fixed in the neutral position and a Microscribe 3D-X digitizer used to digitize three faces of each precision cube. The shoulder joint was then disarticulated and both the humerus and scapula re-mounted on the same jig, independently. The cube faces were re-digitized and relevant points, lines and surfaces were identified and digitized on each humerus and scapula. The humeri were then scanned using a high precision surface laser scanner.

The data collected from both digitizing tools were merged into the same coordinate system and graphically represented. Paired Student’s t-tests were used to compare the inclination and retroversion angles for the two techniques.

Results and discussion: The study found a significant difference in inclination (p less than 0.02) and no difference in retroversion (p equal to 0.75) when the glenoid position was used to calculate humeral head orientation (Inclination: Mean 11.5 deg., StD. 11.2 deg.; Retroversion: Mean 20.5 deg., StD. 6.6 deg.) when compared to using the cartilage/calcar interface (Inclination: Mean 134.1 deg., StD. 1.9 deg.; Retroversion Mean 21.7 deg., StD. 13.9 deg.).

Small deviations in the recovery of head orientation in shoulder arthroplasty may impact on the longevity of an implant. The differences in inclination and retroversion noted in this study may alter the load on the glenoid and/or rotator cuff mechanism in joint replacement. Further research is necessary.

Introduction: Accurate recovery of humeral head geometry in shoulder arthroplasty is an important requirement for a good functional outcome. Despite this, spherical prosthetic components are implanted when the total proximal humerus is described as ovoid¹. However, 60 to 80 % of the head is spherical¹. If, in the normal glenohumeral joint, only the spherical portion is in contact with the glenoid then recovery of normal mechanics is likely with a spherical prosthetic component.

Contact patterns have been examined ex vivo² under static conditions but do not reflect the likely in vivo contact pattern under dynamic loading and have not been correlated to changes in sphericity of the articular surface. A recent study of the distal femur found that thickness of normal articular cartilage is positively correlated with loading³ and, thus, contact.

The objective of this study was to determine the feasibility of using a surface laser scanner to determine cartilage thickness and, therefore, likely contact area and to correlate changes in thickness to changes in sphericity of the articular surface.

Methods: A cadaveric arm without bony deformity or evidence of rotator cuff disease was dissected free of soft tissue and mounted on a rigid block within the frame of a surface laser scanner (Kestrel3D Ltd., UK). The articular surface of the humerus was scanned at a resolution of 200 μm. The cartilage was then dissolved away and the humerus re-scanned. The x,y,z coordinate data of the re-scanned bone were used to match the sub-chondral bone with the cartilage from the previous scan using Pointstream™ software (Kestrel3D Ltd., UK).

The cloud point data for the cartilage and bony surfaces were exported into modelling software (McNeal and Assoc., Seattle, WA) and the surface area of the head divided into ten equal sections. For each slice of both the cartilage and bony surface, the radius of curvature was calculated using a least square fit optimisation technique⁴. The differences in radius of curvature between the cartilage surface and subchondral bone surface were used to calculate the cartilage thickness for each slice. The standard deviation from the radius of curvature was used to calculate the degree of deviation from sphericity.

Results: For the first 60 % of the surface area, the deviation from sphericity was 0.5% of the radius with a cartilage thickness of 0.74 mm. The deviation from sphericity and cartilage thickness for 100% of the articular surface was > 1% and 0.63 mm, respectively.

Conclusions: The experiment proved that the surface laser scanner can be used to elucidate the relationship between contact patterns and articular curvature of the proximal humerus. The changes in sphericity concur with results from previous studies¹. Assuming cartilage thickness correlates to contact patterns at the normal glenohumeral joint, the change in cartilage thickness suggests that contact may occur only at the spherical portion of the head. Knowledge of this relationship may aid in future prosthetic design considerations or in modification of the osteotomy technique. To further support these findings, a 50μm laser scanner is being developed and will be used on a larger sample size.

Introduction: Restoration of original humeral head geometry in shoulder arthroplasty is a necessary requirement and may have a bearing on the longevity of the implant. Modern, adaptable, prosthetic components are believed to allow restoration of the individual’s proximal humeral anatomy, provided a precise osteotomy of the humeral head at the level of the anatomical neck is performed. The osteotomy and reconstruction of the humeral head is based on the assumption that the resected articular segment corresponds to a segment of a sphere oriented, identically, in inclination and retroversion to the original humeral head. Resection, along the mid-anterior portion of the cartilage/calcar border, is understood to create a surface that enables a prosthetic component to be mounted, retroverted and inclinated to the same degree as the original head geometry. The objective of this study was to determine the degree of variation in humeral head retroversion relative to the superior and inferior borders of the proximal humeral articular surface.

Methods: Twenty-eight fresh frozen human cadaveric full arms were dissected free of soft tissue to expose the proximal humerus. The distal end of the humeral shaft was potted in PMMA and fixed rigidly in a custom–built jig. The following points and lines were identified and marked on each specimen:

the circumference of the anatomical neck;

A Microscribe 3D-X digitizer was used to digitize the points and lines. The data for each humerus were imported into Rhinoceros NURBS modelling software and graphically represented. The constructed graphical model was used to divide the articular portion of the humeral head into six equal sections in the axial plane. The retroversion angle, relative to the epicondyles, was calculated for each section.

Results: A linear decrease in retroversion angle was noted from the most superior to most inferior point on the proximal humeral articular surface. The retroversion angle was greatest at the level of the insertion of the supraspinatus tendon (34.2deg +/−13.7deg) and least at the inferior cartilage/calcar interface (24.3deg +/−10.2deg).

Discussion: Accurate recovery of humeral head geometry is a requirement in order to achieve good function. The variability in retroversion, as it relates to its point of measurement, may effect the accuracy of pre-operative assessment of a patient’s humeral head geometry as well as the osteotomy during shoulder arthroplasty, and, thus, may impact on joint range of motion and stability post-operatively. Further investigation is warranted.