Evan P. Roush

Comparison of Proximal and Distal Oblique Second Metatarsal Osteotomies with Varying Achilles Tendon Tension: Biomechanical Study in a Cadaver Model.

BACKGROUND The optimal surgery for reducing pressure under the second metatarsal head to treat metatarsalgia is unknown. We tested our hypothesis that a proximal oblique dorsiflexion osteotomy of the second metatarsal would decrease second-metatarsal plantar pressures in a cadaver model with varying Achilles tendon tension. We also tested the plantar pressure effects of two popular techniques of distal oblique osteotomy. METHODS Twelve fresh-frozen feet from six cadavers were randomly assigned to either the distal osteotomy group (a classic distal oblique osteotomy followed by a modified distal oblique osteotomy) or proximal metatarsal osteotomy group. Each specimen was tested intact and then after the osteotomy or osteotomies. The feet were loaded with 0, 300, and 600 N of Achilles tendon tension and a 400-N ground reaction force. Plantar pressures were measured by a pressure sensitive mat and analyzed in sections located under each metatarsal. RESULTS The proximal metatarsal osteotomy significantly reduced average pressures beneath the second metatarsal head during both 300 and 600 N of Achilles tendon loading by an average of 19.4 and 29.7 kPa, respectively (p < 0.05). The modified distal oblique osteotomy significantly decreased these pressures during 600 N of Achilles tendon loading, by a mean of 20.2 kPa, which was to a lesser extent than the proximal metatarsal osteotomy. Interestingly, the classic distal oblique osteotomy was not found to have significant effects on pressures beneath the second metatarsal head. CONCLUSIONS The proximal oblique dorsiflexion metatarsal osteotomy may be the most effective procedure for decreasing plantar pressures under the second metatarsal. The modified distal oblique osteotomy may be the second most effective. CLINICAL RELEVANCE The findings of this biomechanical study help shed light on which of the common second metatarsal osteotomies are best for decreasing plantar pressures.

Effect of ulnar tunnel location on elbow stability in double-strand lateral collateral ligament reconstruction

BACKGROUND Double-strand lateral ulnar collateral ligament (LUCL) reconstruction is an effective treatment for posterolateral rotatory instability (PLRI) of the elbow, but anatomic landmarks for ulnar tunnel placement are often difficult to identify intraoperatively, which potentially can result in a nonanatomic LUCL reconstruction. This study investigated the effect of ulnar tunnel location on joint stability in double-strand LUCL reconstruction. METHODS PLRI was artificially created in 7 cadaveric elbows, and double-strand LUCL reconstruction was performed. Five different ulnar tunnels were made along the length of the ulna. In each specimen, each possible pair of 2 tunnels (10 total) were used for graft passage. Varus and posterolateral joint gapping was measured after joint loading using a 3-dimensional digitizer system and X-ray image intensifier. RESULTS No significant gapping was observed at the posterolateral ulnohumeral joint regardless of the location of the ulnar tunnels (P > .05). In contrast, the lateral radiocapitellar joint showed statistically significant varus gapping when both ulnar tunnels were placed proximal to the radial head-neck junction (P < .05). DISCUSSION This findings of study suggest that the location of the ulnar tunnels may not be as critical as that of the humeral tunnel during double-strand LUCL reconstruction and that posterolateral rotatory elbow stability can be achieved reasonably well as long as at least 1 of the 2 ulnar tunnels is located at or distal to the radial head-neck junction level.

Time course of peri-implant bone regeneration around loaded and unloaded implants in a rat model

The time‐course of cancellous bone regeneration surrounding mechanically loaded implants affects implant fixation, and is relevant to determining optimal rehabilitation protocols following orthopaedic surgeries. We investigated the influence of controlled mechanical loading of titanium‐coated polyether‐ether ketone (PEEK) implants on osseointegration using time‐lapsed, non‐invasive, in vivo micro‐computed tomography (micro‐CT) scans. Implants were inserted into proximal tibial metaphyses of both limbs of eight female Sprague–Dawley rats. External cyclic loading (60 or 100 μm displacement, 1 Hz, 60 s) was applied every other day for 14 days to one implant in each rat, while implants in contralateral limbs served as the unloaded controls. Hind limbs were imaged with high‐resolution micro‐CT (12.5 μm voxel size) at 2, 5, 9, and 12 days post‐surgery. Trabecular changes over time were detected by 3D image registration allowing for measurements of bone‐formation rate (BFR) and bone‐resorption rate (BRR). At day 9, mean %BV/TV for loaded and unloaded limbs were 35.5 ± 10.0% and 37.2 ± 10.0%, respectively, and demonstrated significant increases in bone volume compared to day 2. BRR increased significantly after day 9. No significant differences between bone volumes, BFR, and BRR were detected due to implant loading. Although not reaching significance (p = 0.16), an average 119% increase in pull‐out strength was measured in the loaded implants.

Biomechanical benefits of anterior offsetting of humeral head component in posteriorly unstable total shoulder arthroplasty: A cadaveric study

Restoration of joint stability during total shoulder arthroplasty can be challenging in the face of severe glenoid retroversion. A novel technique of humeral head component anterior‐offsetting has been proposed to address posterior instability. We evaluated the biomechanical benefits of this technique in cadaveric specimens. Total shoulder arthroplasty was performed in 14 cadaveric shoulders from 7 donors. Complementary shoulders were assigned to either 10° or 20° glenoid retroversion, with retroversion created by eccentric reaming. Two humeral head component offset positions were tested in each specimen: The anatomic (posterior) and anterior (reverse). With loads applied to the rotator cuff and deltoid, joint contact pressures and the force and energy required for posterior humeral head translation were measured. The force and energy required to displace the humeral head posteriorly increased significantly with the anterior offset position compared to the anatomic offset position. The joint contact pressures were significantly shifted anteriorly, and the joint contact area significantly increased with the anterior offset position. Anterior offsetting of the humeral head component increased the resistance to posterior humeral head translation, shifted joint contact pressures anteriorly, and increased joint contact area, thus, potentially increasing the joint stability in total shoulder arthroplasty with simulated glenoid retroversion.

Intraoperative fluoroscopic assessment of proper prosthetic radial head height.

BACKGROUND Selecting a properly sized radial head prosthesis is imperative during radial head replacement. Although there has been much emphasis on avoiding overlengthening of the radius, little has been studied about how to avoid shortening. The purpose of this study was to characterize how a radial head replacement appears on intraoperative fluoroscopy depending on the height of the prosthetic radial head. METHODS Articular cartilage thickness of the radial head was measured in 9 cadaveric elbows. Radial head replacement was performed in each specimen with 4 different prosthetic head heights: 4 mm and 2 mm shortening, anatomic, and 2 mm overlengthening. Anteroposterior fluoroscopic images were obtained for each head height, and the prosthetic radial head height was measured at 3 forearm positions (supination, neutral, and pronation) using the subchondral bone of the lateral edge of the coronoid at the reference point. RESULTS The mean cartilage thickness of the radial head was 1.3 ± 0.4 mm. The prosthetic radial head appeared 2.2 ± 0.4 mm more proximal than the subchondral bone of the coronoid lateral edge in anteroposterior radiographs when the articular surface of the prosthesis was completely even with the coronoid articular surface. Unlike the native radial head, a prosthetic radial head showed a significant change of height with different forearm rotation (P < .001). DISCUSSION This study found that a perfectly anatomic radial head replacement appears overlengthened by approximately 2 mm in intraoperative radiographs. This finding can be useful in guiding the appropriate height of a prosthetic radial head.

Three-Dimensional Morphometric Modeling Measurements of the Calcaneus in Adults with Stage IIB Posterior Tibial Tendon Dysfunction: A Pilot Study

Background: The pathophysiology of adult-acquired flatfoot deformity (AAFD) is not fully explained by degeneration of the posterior tibial tendon alone. While a shortened or dysplastic lateral column has been implicated in flatfoot deformity in pediatrics, there is no study that has quantified the degree of dysplasia in adults with a stage IIb flatfoot deformity, or if any exists at all. Methods: An institutional radiology database was queried for patients with posterior tibial tendon dysfunction (PTTD) who had computed tomography (CT) performed. Controls were patients receiving CT scan for an intra-articular distal tibia fracture without preexisting foot or calcaneal pathology. Clinical notes, physical examination, and weightbearing radiographs were used to find patients that met clinical criteria for stage IIb PTTD. Morphometric measurements of the calcanei were performed involving the length of the calcaneal axis (LCA), height of the anterior process (HAP), and length of the anterior process (LAP). All measurements were performed independently by separate observers, with observers blinded to group assignment. We considered a difference of ±4 mm as our threshold. Results: 7 patients and 7 controls were available for reconstruction and analysis. On average, the LCA was 3.1 mm shorter in patients with stage IIb PTTD compared with controls (P < .05). The LAP was shorter in PTTD patients compared with controls 3.4 mm (P < .001). Conclusions: Our results support the hypothesis that the calcaneus of adult patients with stage IIb AAFD is dysplastic when compared with healthy controls, which further supports the utility of lateral column lengthening. Levels of Evidence: Level III: Case-control study

Morphometric Measurements of the Calcaneus in Adults with Stage IIb, Posterior Tibial Tendon Dysfunction: Is the Lateral Column Short?

Category: Hindfoot Introduction/Purpose: The pathophysiology of adult-acquired flatfoot deformity (AAFD) is not fully explained by degeneration of the posterior tibial tendon alone. While a shortened or dysplastic lateral column has been implicated in flatfoot deformity in pediatric population, there is no study that has quantified the degree of shortening or dysplasia in adults with a stage IIb flatfoot deformity, or if any exists at all. The purpose of this study was to use reconstructive 3D modeling from computed tomography (CT) scans of the calcaneus in order to perform three-dimensional morphometric measurements of the lateral column in patients with stage IIb posterior tibial tendon dysfunction (PTTD) compared to controls in an effort to better understand the morphology of patients with AAFD. Methods: After IRB approval, an institutional radiology database was queried for patients with PTTD who had CT performed between January 2011 and June 2016. Controls were patients receiving CT scan for an intraarticular distal tibia fracture without preexisting foot or calcaneal pathology. Clinical office notes, physical examination, and weight-bearing radiographs were used to identify patients that met clinical criteria for stage IIb PTTD. A 1:1 match was performed using age, laterality, gender, and BMI. Morphometric measurements of the calcanei were performed involving the length of the calcaneal axis (LCA), height of the anterior process (HAP), and length of the anterior process (LAP) (Figure 1). Linear mixed-effects models were used to assess the differences between control and PTTD patients with respect to LAP, HAP, and LCA measurements, with also considering measurements from 3 independent observers. We considered a difference of ± 4 mm as our threshold of clinical significance. Results: Of the 3586 CT within our institutional database, a total of 14 patients were available for reconstruction and analysis. There were no statistical differences detected between patient characteristics or demographics between these groups. On average, the long axis of the calcaneus (LCA) was 3.1 mm shorter (95% confidence interval: 0.43-5.76 mm) in patients with stage IIb PTTD compared to controls (p<0.05). Additionally, the distance from the articular margin of the posterior facet to the anterior process (LAP) was shorter in PTTD patients compared to controls 3.35 mm (p<0.001; 95% confidence interval: 1.82- 4.88). Comparison of observers demonstrated high agreement between LCA and LAP measurements, as illustrated by satisfactory concordance correlation coefficients. Conclusion: Our results support the hypothesis that the calcaneus of adult patients with stage IIb AAFD is, indeed, dysplastic when compared to healthy controls, which further supports the utility of LCL. Analysis of these results, taken together with previous literature, may suggest the use of a smaller graft between 4-6 mm as ideal when performing this procedure.

The Role of 3D Reconstruction True-Volume Analysis in Osteochondral Lesions of the Talus: A Case Series

Background: Evaluation and management of osteochondral lesions of the talus (OLTs) often warrant advanced imaging studies, especially in revision or cases with cystic defects. It is possible that orthopedic surgeons may overestimate the size and misinterpret the morphology of OLT from conventional computed tomography (CT), thereby influencing treatment strategies. The purpose of this study was to determine the utility of a novel means to estimate the true-volume of OLTs using 3D reconstructed images and volume analysis. Methods: With Institutional Review Board approval, an institutional radiology database was queried for patients with cystic OLTs that failed previous microfracture, having compatible CT scans and magnetic resonance imaging (MRI) between 2011 and 2016. Fourteen patients met inclusion criteria. Of these, 5 cases were randomly selected for 3D CT reconstruction modeling. Ten orthopedic surgeons independently estimated the volume of these 5 OLTs via standard CT. Then 3D reconstructions were made and morphometric true-volume (MTV) analysis measurements of each OLT were generated. The percent change in volumes from CT were compared to MTVs determined from 3D reconstructive analysis. Results: On average, the volume calculated by conventional CT scanner grossly overestimated the actual size of the OLTs. The volume calculated on conventional CT scanner overestimated the size of OLTs compared to the 3D MTV reconstructed analysis by 285% to 864%. Conclusions: Our results showed that conventional measurements of OLTS with CT grossly overestimated the size of the lesion. The 3D MTV analysis of cystic osteochondral lesions may help clinicians with preoperative planning for graft selection and appropriate volume while avoiding unnecessary costs incurred with overestimation. Level of Evidence: Level IV, case series.

Effect of Patellar Tunnel Placement on Fracture Risk after MPFL Reconstruction- A Cadaveric Study

Objectives: Patella fracture is a rare complication after medial patellofemoral ligament (MPFL) reconstruction. Though many of the cases in the literature have been precipitated by trauma, the surgical factors that may lead to a higher risk of fracture are not well understood. The purpose of our study was to determine if transosseous tunnels that exit through the anterior cortex of the patella, and transverse bone tunnels have lower tensile load to failure as compared to control, and may predispose to post-operative patellar fracture. Methods: Fresh-frozen cadaveric human patellas were randomized to one of three groups: a control group with unmodified intact patellas, a group with two transverse tunnels (TT) drilled in the superior third of the patella that did not violate the anterior cortex, and a group with two transversetunnels that breach anterior cortex of the patella (PA). Patellas were connected to a freeze clamp mechanism via the remaining quadriceps and patellar tendons. A load cell was connected in series with the quadriceps clamp to measure maximum load to failure with a maximum load of 9000N. The angle of pull was fixed at 45 degrees, with the patella set in the trochlear groove of a composite synthetic femur. Patellas were cyclically loaded to 500 N for a total of 100 cycles. Specimens that did not fail during cyclic loading were then loaded to failure defined as fracture or tendon rupture. At failure, fluoroscopy was used to confirm a fracture if present and maximum load was recorded. The mean and standard deviation (STD) for each group were recorded. ANOVA and Student-T tests were used to identify significant differences between groups. Results: A total of 26 patellas were randomized and tested in this study. There were 12 male and 14 female patellas ranging in age from 37-95 years. There was no significant difference in the average age among the groups (Mean = 71.4 years, STD = 11.5 years, P =0.96). None of the patellas failed during cyclic loading alone. Control, TT and PA groups failed at 1915 N (STD= 508N), 1901 N (STD= 884N), and 1640 N (STD= 625N) respectively. This represents a 14% difference in means between Control and PA and Control and TT tunnels. There was no statistically significant difference between control and TT (p=.969), control and PA (p=.321), and TT and PA (p=.488). Subset analysis of fractures only through bone tunnels did not affect the significance. Conclusion: Our results show that breeching of the anterior cortex and transosseous tunnels that do not breach the anterior cortex during MPFL reconstruction do not significantly decrease the load to failure when compared to native patellas and, thus, may not pose an increased risk for patellar fracture. Further research is needed to analyze if other surgical factors may predispose to this complication.

Biomechanical consequences of adding plantar fascia release to metatarsal osteotomies: Changes in forefoot plantar pressures.

Destruction of the normal metatarsal arch by a long metatarsal is often a cause for metatarsalgia. When surgery is warranted, distal oblique, or proximal dorsiflexion osteotomies of the long metatarsal bones are commonly used. The plantar fascia has anatomical connection to all metatarsal heads. There is controversial scientific evidence on the effect of plantar fascia release on forefoot biomechanics. In this cadaveric biomechanical study, we hypothesized that plantar fascia release would augment the plantar metatarsal pressure decreasing effects of two common second metatarsal osteotomy techniques. Six matched pairs of foot and ankle specimens were mounted on a pressure mat loading platform. Two randomly assigned surgery groups, which had received either distal oblique, or proximal dorsiflexion osteotomy of the second metatarsal, were evaluated before and after plantar fasciectomy. Specimens were loaded up to a ground reaction force of 400 N at varying Achilles tendon forces. Average pressures, peak pressures, and contact areas were analyzed. Supporting our hypothesis, average pressures under the second metatarsal during 600 N Achilles load were decreased by plantar fascia release following proximal osteotomy (p < 0.05). However contrary to our hypothesis, peak pressures under the second metatarsal were significantly increased by plantar fascia release following modified distal osteotomy, under multiple Achilles loading conditions (p < 0.05). Plantar fasciotomy should not be added to distal metatarsal osteotomy in the treatment of metatarsalgia. If proximal dorsiflexion osteotomy would be preferred, plantar fasciotomy should be approached cautiously not to disturb the forefoot biomechanics.