Quentin A. Fogg

Transarticular shear fractures of the distal humerus

BACKGROUND Capitellar fractures result from shearing and wedging forces transmitted to the elbow that create complex injury patterns that are difficult to stabilize. The fracture often extends into the trochlea and is associated with posterior comminution of the humerus and soft tissue injury. Diverse fixation techniques are required to restore the anatomy perfectly to ensure elbow function is regained. MATERIALS AND METHODS This study presents the results of treatment of 26 patients followed up prospectively and treated within a week of injury. Clinical and radiographic evaluations were done annually by an independent reviewer, and the Mayo Elbow Performance Index (MEPI) was calculated. RESULTS Results were excellent in 9 patients, good in 9, and fair in 8 when assessed at an average of 46 months (range, 19-94 months) postoperatively using the MEPI, which averaged 81.3 (range 65-100). The poorer results occurred in patients with severe injuries associated with posterior comminution of the humerus and who required more extensive reconstructive procedures. All pain scores improved significantly and activities of daily living were restored in all groups, All returned to employment within 6 months, but 6 (3 type 2 and 3 type 3) had altered their roles from manual to administrative work. CONCLUSION This series reflects the challenges in reconstructing precisely this cartilage-covered sphere, especially when there are multiple fragments. Modern techniques of fracture stabilization that concentrate on restoring a circular structure may require a different approach and engineering solutions. LEVEL OF EVIDENCE Level 4; Case series, treatment study.

Where to find facial artery perforators: A reference point *

Reconstructive surgery of the midface using facial artery perforator (FAP) flaps is being used more frequently now as it has been reported to provide better aesthetic results and reduce a traditional two-stage procedure to a one-stage technique. However, the wide acceptance of this approach is limited by a poor understanding of the anatomy associated with this technique. This was investigated through a cadaveric study. The facial artery (FA) of 16 cadaveric half-faces were each identified, cannulated with coloured latex and then dissected to give an accurate and quantified description of FA perforating branches. A lateral-view picture of each specimen was taken and analysed using ImageJ 1.42q. Cadaveric dissections showed that each hemiface could be regarded as a single entity. The values of the means were as follows: FA length=116±22 mm, FA diameter=2.62±0.74 mm, number of FAPs=4±2, FAP length=14.12±3.46 mm and FAP diameter=0.94±0.29 mm. A reference point, A, where FAPs were consistently found to originate, was also identified. Therefore, the FAP flap is a viable and valuable addition to plastic reconstructive techniques. The localisation of point A with precise measurements can facilitate the design and use of such FAP flaps for the reconstruction of nasal, as well as perinasal and perioral defects.

Three-dimensional analysis of the palmar plate and collateral ligaments at the proximal interphalangeal joint:

The purpose of this study was to analyze the palmar plate complex at the proximal interphalangeal joint using a three-dimensional (3D) technique, which makes it easier to understand the dimensions of structures and their relationship to the adjacent components. This method allows individual elements to be removed virtually, facilitating clearer observation of each component. Sixteen cadaveric specimens were dissected and reconstructed in a 3D virtual environment. The palmar plate is made up of a distal, fibrous portion and a proximal, membranous portion, which anchors distally on the base of the middle phalanx and is continuous with the bilateral check-rein ligaments proximally. The accessory collateral ligaments and the A3 pulley suspend the palmar plate laterally.

Repeatability and accuracy of a non-invasive method of measuring internal and external rotation of the tibia

PurposeThe ability to quantify rotational laxity of the knee would increase understanding of functional rotatory instability, identify the best treatment methods for soft tissue injury, and have a role in diagnosis of soft tissue injury. This study aimed to report the reliability, repeatability and precision of a non-invasive adaptation of image-free navigation technology by comparing with a validated invasive system used for computer-assisted surgery.MethodsTwelve cadaveric lower limbs were tested with a commercial image-free navigation system using passive trackers secured by bone screws. They were then tested a non-invasive fabric-strap system. Manual application of torque was used consistent with clinical examination to rotate the tibia to the end of internal rotation and external rotation range. Measurements were taken at 10° intervals from full extension to 90° flexion, and protocol was repeated twice using each system. Intraclass correlation coefficient (ICC) was used to reflect reliability of measurements. At each flexion interval, coefficient of repeatability (CR) was calculated for each system, and limits of agreement (LOA) were used to reflect agreement between the systems.ResultsThe results for internal and external rotation were combined throughout flexion: ICC invasive; 0.94 (0.86–0.99), non-invasive; 0.92 (0.7–0.99), CR invasive; 2.4° (1.3–4.8°), non-invasive; 3.5° (1.8–6.6), LOA; 8.2° (4.3–13.5).ConclusionNon-invasive optical tracker fixation gives improved agreement with a validated method of measurement compared with devices measuring tibial rotation by foot position. This system gives the added possibility of dynamic, weight-bearing testing in the clinically important range of 0°–30° knee flexion without the need for any limb restraint.

Quantitative assessment of the subchondral vascularity of the talar dome: A cadaveric study

BACKGROUND The arterial supply to the talus has been extensively studied previously but never to specifically examine the subchondral region of the talar dome, a frequent site of localised pathology. This study aims to analyse and quantify the subchondral vascularity of the talar dome. METHODS We performed cadaveric arterial injection studies. After processing, the vascularity to the subchondral region of the talar dome was visualised and mapped using three-dimensional computer technology, then quantified and reported using a nine-section anatomical grid. RESULTS The areas of relative poor perfusion across the talar dome are the posterior/medial, posterior/lateral and middle/medial sections of a nine-section grid. The rest of the subchondral region shows more richly vascularised bone. CONCLUSIONS The vascularity of the subchondral surface of the talar dome is not uniformly distributed. This may be relevant to the aetiology and management of osteochondral lesions and shows some correlation with their more frequent locations.

An Anatomical Study Comparing Two Surgical Approaches for Isolated Talonavicular Arthrodesis

Background: Two operative approaches are commonly used for isolated talonavicular arthrodesis: the medial and the dorsal approach. It is recognized that access to the lateral aspect of the talonavicular joint can be limited when using the medial approach, and it is our experience that using the dorsal approach addresses this issue. We performed an anatomical study using cadaver specimens, to compare the amount of articular surface that can be accessed by each operative approach. Methods: Medial and dorsal approaches to the talonavicular joint were performed on each of 11 cadaveric specimens (10 fresh frozen, 1 embalmed). Distraction of the joint was performed as used intraoperatively and the accessible area of articular surfaces was marked for each of the 2 approaches using a previously reported technique. Disarticulation was performed and the marked surface area was quantified using an immersion digital microscribe, allowing a 3-dimensional virtual model of the articular surfaces to be assessed. Results: The median percentage of total accessible talonavicular articular surface area for the medial and dorsal approaches was 71% and 92%, respectively (Wilcoxon signed-rank test, P < .001). Conclusion: This study provides quantifiable measurements of the articular surface accessible by the medial and dorsal approaches to the talonavicular joint. Clinical Relevance: These data support for the use of the dorsal approach for talonavicular arthrodesis, particularly in cases where access to the lateral half of the joint is necessary.

Non-invasive quantification of lower limb mechanical alignment in flexion.

Abstract Objective: Non-invasive navigation techniques have recently been developed to determine mechanical femorotibial alignment (MFTA) in extension. The primary aim of this study was to evaluate the precision and accuracy of an image-free navigation system with new software designed to provide multiple kinematic measurements of the knee. The secondary aim was to test two types of strap material used to attach optical trackers to the lower limb. Methods: Seventy-two registrations were carried out on 6 intact embalmed cadaveric specimens (mean age: 77.8 ± 12 years). A validated fabric strap, bone screws and novel rubber strap were used to secure the passive tracker baseplate for four full experiments with each knee. The MFTA angle was measured under the conditions of no applied stress, valgus stress, and varus stress. These measurements were carried out at full extension and at 30°, 40°, 50° and 60° of flexion. Intraclass correlation coefficients, repeatability coefficients, and limits of agreement (LOA) were used to convey precision and agreement in measuring MFTA with respect to each of the independent variables, i.e., degree of flexion, applied coronal stress, and method of tracker fixation. Based on the current literature, a repeatability coefficient and LOA of ≤3° were deemed acceptable. Results: The mean fixed flexion for the 6 specimens was 12.8° (range: 6–20°). The mean repeatability coefficient measuring MFTA in extension with screws or fabric strapping of the baseplate was ≤2°, compared to 2.3° using rubber strapping. When flexing the knee, MFTA measurements taken using screws or fabric straps remained precise (repeatability coefficient ≤3°) throughout the tested range of flexion (12.8–60°); however, using rubber straps, the repeatability coefficient was >3° beyond 50° flexion. In general, applying a varus/valgus stress while measuring MFTA decreased precision beyond 40° flexion. Using fabric strapping, excellent repeatability (coefficient ≤2°) was observed until 40° flexion; however, beyond 50° flexion, the repeatability coefficient was >3°. As was the case with precision, agreement between the invasive and non-invasive systems was satisfactory in extension and worsened with flexion. Mean limits of agreement between the invasive and non-invasive system using fabric strapping to assess MFTA were 3° (range: 2.3–3.8°) with no stress applied and 3.9° (range: 2.8–5.2°) with varus and valgus stress. Using rubber strapping, the corresponding values were 4.4° (range: 2.8–8.5°) with no stress applied, 5.5° (range: 3.3–9.0°) with varus stress, and 5.6° (range: 3.3–11.9°) with valgus stress. Discussion: Acceptable precision and accuracy may be possible when measuring knee kinematics in early flexion using a non-invasive system; however, we do not believe passive trackers should be mounted with rubber strapping such as was used in this study. Flexing the knee appears to decrease the precision and accuracy of the system. The functions of this new software using image-free navigation technology have many potential clinical applications, including assessment of bony and soft tissue deformity, pre-operative planning, and post-operative evaluation, as well as in further pure research comparing kinematics of the normal and pathological knee.

The metatarsosesamoid joint: An in vitro 3D quantitative assessment

BACKGROUND The anatomy of the first metatarsophalangeal (MTP) joint, particularly the metatarsosesamoid articulation, remains poorly understood. Our goal was to quantitatively define the excursion of the sesamoids. METHODS Seven cadavers were dissected to assess the articulating surfaces throughout a normal range of motion. The dissections were digitally reconstructed in various positions using a MicroScribe. RESULT For first MTP joint, excursion averaged 14.7mm for the tibial sesamoid in the sagittal plane and 7.5mm for the fibular sesamoid. The sesamoids also moved medially to laterally when the joint was dorsiflexed. For the maximally dorsiflexed joint, excursion averaged 2.8mm for the tibial sesamoid and 3.5mm for the fibular sesamoid. CONCLUSION Hallucal sesamoids appear to have differential tracking: the tibial sesamoid has greater longitudinal excursion; the fibular sesamoid has greater lateral excursion. The anatomical data will interest those involved with the design of an effective hallux arthroplasty.

Quantitative measurement of lower limb mechanical alignment and coronal knee laxity in early flexion

BACKGROUND Non-invasive quantification of lower limb alignment using navigation technology is now possible throughout knee flexion owing to software developments. We report the precision and accuracy of a non-invasive system measuring mechanical alignment of the lower limb including coronal stress testing of the knee. METHODS Twelve cadaveric limbs were tested with a commercial invasive navigation system against the non-invasive system. Coronal mechanical femorotibial (MFT) alignment was measured with no stress, then 15 Nm varus and valgus applied moments. Measurements were recorded at 10° intervals from extension to 90° flexion. At each flexion interval, coefficient of repeatability (CR) tested precision within each system, and limits of agreement (LOA) tested agreement between the two systems. Limits for CR & LOA were set at 3° based on requirements for surgical planning and evaluation. RESULTS Precision was acceptable throughout flexion in all conditions of stress using the invasive system (CR ≤ 1.9°). Precision was acceptable using the non-invasive system from extension to 50° flexion (CR ≤ 2.4°), beyond which precision was unacceptable (> 3.4°). With no coronal stress applied, agreement remained acceptable from extension to 40° (LOA ≤ 2.4°), and when 15 Nm varus or valgus stress was applied agreement was acceptable from extension to 30° (LOA ≤ 2.9°). Higher angles of knee flexion had a negative impact on precision and accuracy. CONCLUSION & CLINICAL RELEVANCE The non-invasive system provides reliable quantitative data in-vitro on coronal MFT alignment and laxity in the range relevant to assessment of collateral ligament injury, pre-operative planning of arthroplasty and flexion instability following arthroplasty. In-vivo validation should be performed.

Congenital pseudarthrosis of clavicle: illustrated operative technique and histological findings

Congenital pseudarthrosis of the clavicle is a rare condition present at birth but often diagnosed later in childhood. Indications for surgical treatment include pain, deformity or neurovascular compromise. Reconstruction usually involves resection of the pseudarthrosis, placement of iliac crest bone graft or graft substitute and internal fixation. In this paper, we present a case of congenital pseudarthrosis of the clavicle in a 9-year-old boy who was treated with plate fixation and bone autograft. The majority of patients who undergo surgery because of cosmetic or functional problem heal well and proceed with a normal, unrestricted life. However, for those patients who are not bothered by the cosmetic appearance of the pseudarthrosis and are asymptomatic in that they are not functionally limited, non-surgical treatment is a viable option.