Deviation analysis of C2 translaminar screw placement assisted by a novel rapid prototyping drill template: a cadaveric study

Purpose

The goal of this study is to evaluate the accuracy of patient-specific CT-based rapid prototype drill templates for C2 translaminar screw insertion.

Methods

Volumetric CT scanning was performed in 32 cadaveric cervical spines. Using computer software, the authors constructed drill templates that fit onto the posterior surface of the C2 vertebrae with drill guides to match the slope of the patient’s lamina. Thirty-two physical templates were created from the computer models using a rapid prototyping machine. The drill templates were used to guide drilling of the lamina and post-operative CT images were obtained. The entry point and direction of the planned and inserted screws were measured and compared.

Results

Sixty-four C2 translaminar screws were placed without violating the cortical bone of a single lamina. The bilateral average transverse angle of intended and actual screw for C2TLS was 56.60 ± 2.22°, 56.38 ± 2.51°, 56.65 ± 2.24°, 56.39 ± 2.45°. The bilateral mean coronal angle of the planned and actual screw for C2TLS was 0°, 0°, −0.07 ± 0.32°, 0.12 ± 0.57°. The average displacement of the entry point of the superior and inferior C2TLS in the x, y, z axis was 0.27 ± 0.85, 0.49 ± 1.46, −0.28 ± 0.69, 0.43 ± 0.88, 0.38 ± 1.51, 0.23 ± 0.64 mm.

Conclusion

The small deviations seen are likely due to human error in the form of small variations in the surgical technique and use of software to design the prototype. This technology improves the safety profile of this fixation technique and should be further studied in clinical applications.     

Outcomes after shoulder arthroplasty revision with glenoid reconstruction and bone grafting

Purpose

Extensive glenoid bone loss after failed shoulder arthroplasty represents a challenge for revision arthroplasty. Treatment options vary widely and have been a source of controversy among experts.

Methods

Between 2004 and 2010, a total of 17 patients underwent glenoid reconstruction surgery using an autologous iliac crest bone graft and secondary revision arthroplasty due to extensive glenoid bone loss after failed previous total shoulder arthroplasty. The outcomes were assessed by means of clinical examination, Constant score, and bi-plane radiography as well as pre-, postoperative and follow-up CT.

Results

Before the revision surgery, the mean Constant score was 24 ± 17 and improved to 40 ± 13 after the glenoid rebuilding and revision arthroplasty. CT imaging revealed adequate glenoid bone stock restoration with no relevant graft resorption or loosening of the glenoid. The average postoperative antero-posterior diameter of the glenoid was 28 ± 3 mm which had decreased to 25 ± 3 mm at follow-up. The average postoperative version of the glenoid was 95.7° ± 6° and had decreased to 98.5° ± 4° at follow-up. Both the glenoid version and diameter had changed significantly (P < 0.001) comparing postoperative and follow-up CT-scans.

Conclusion

Glenoid reconstruction surgery using an iliac crest bone-block autograft prior to revision arthroplasty represents a valuable salvage procedure in cases of extensive glenoid bone loss after primary shoulder arthroplasty. Sufficient glenoid bone stock restoration is indispensable for reliable fixation of glenoid components and in turn a satisfactory clinical outcome.     

Pullout strength of all suture anchors in the repair of rotator cuff tears: a biomechanical study

Purpose

We evaluated the biomechanical strength of two all suture anchors (ASA) of reduced diameter (1.4 mm) and compared them with the standard screw anchor (SA) with larger diameter (5.5 mm) used in rotator cuff tears.

Methods

We conducted 30 uniaxial vertical pullout tests using Material Testing System Instron 5566A until failure of the anchorage defined as rupture of the threads or anchor or detachment of the anchor. Anchor fixation was on tuberosities of fresh bovine humerus bone. ASAs were spaced four millimetres apart and were compared with a control SA implanted on the same greater tubercle at two centimetres. The tests were all performed at room temperature in a dry environment. Tensile loads (10 mm/min) were applied parallel to the axis of insertion. A preloading of 10 N was used to overcome loading artifacts of the test sample at the beginning of the test.

Results

Student’s t test showed no statistically significant difference between anchors in terms of load to failure (ASA: force 265.06 ± 87.25 N versus SA : 325.35 ± 113.46 N; p = 0.09) and mean elongation at rupture (ASA : 23 ± 7 mm versus SA : 21 ± 6 mm; p = 0.46).

Conclusions

In vitro, this experimental study showed no statistically significant difference in pullout strength and displacement between ASA and SA at a chosen level of significance (p < 0.05).     

Fluoroscopy-guided retrograde core drilling and cancellous bone grafting in osteochondral defects of the talus

Purpose

In undetached osteochondral lesions (OCL) of the talus both revitalisation of the subchondral necrosis and cartilage preservation are essential. For these cases, we assess the results of minimally invasive retrograde core drilling and cancellous bone grafting.

Methods

Forty-one osteochondral lesions of the talus (12x grade I, 22x grade II and 7x grade III according to the Pritsch classification, defect sizes 7–14 mm) in 38 patients (mean age 33.2 years) treated by fluoroscopy-guided retrograde core drilling and autologous cancellous bone grafting were evaluated by clinical scores and MRI. The mean follow-up was 29.0 (±13) months.

Results

The AOFAS score increased significantly from 47.3 (±15.3) to 80.8 (±18.6) points. Lesions with intact cartilage (grades I and II) had a tendency to superior results than grade III lesions (83.1 ± 17.3 vs. 69.4 ± 22.2 points, p = 0.07). First-line treatments and open distal tibial growth plates led to significantly better outcomes (each p < 0.05). Age, gender, BMI, time to follow-up, defect localisation or a traumatic origin did not influence the score results. On a visual analogue scale pain intensity reduced from 7.5 (±1.5) to 3.7 (±2.6) while subjective function increased from 4.6 (±2.0) to 8.2 (±2.3) (each p < 0.001). In MRI follow-ups, five of the 41 patients showed a complete bone remodelling. In two cases demarcation was detectable.

Conclusions

The technique reported is a highly effective therapeutic option in OCL of the talus with intact cartilage grades I and II. However, second-line treatments and grade III lesions with cracked cartilage surface can not be generally recommended for this procedure.     

The locking attachment plate for proximal fixation of periprosthetic femur fractures-a biomechanical comparison of two techniques

Purpose

Mechanical properties of a locking attachment plate construct (LAP-LCP), allowing bicortical screw placement laterally to the prosthesis stem, are compared to a cerclage-LCP construct.

Methods

Eight right synthetic femora with implanted uncemented hip endoprosthesis were cut distally and fixed with LCP, monocortical locking screws and either LAP (n = 4) or cerclage (n = 4). Cyclic testing was performed with monotonically increasing sinusoidal load until failure. Relative movements at the plate–femur interface were registered by motion tracking. Statistical differences were detected by unpaired t-test and general linear model repeated measures.

Results

Stiffness of the LAP-LCP was significantly higher at the beginning (875.4 N/mm ± 29.8) and after 5000 cycles (1213.0 N/mm ± 101.1) compared to the cerclage-LCP (644.96 N/mm ± 50.1 and 851.9 N/mm ± 81.9), with p = 0.013. Relative movements for AP-bending (B) and axial translation (T) of the LAP-LCP at the beginning (0.07° ± 0.02, 0.20 mm ± 0.08), after 500 cycles (0.16° ± 0.10, 0.26 mm ± 0.07) and after 5000 cycles (0.26° ± 0.11, 0.31 mm ± 0.07) differed significantly from the cerclage-LCP (beg.: 0.26° ± 0.04, 0.28 mm ± 0.05; 500 cyc: 0.47° ± 0.03, 0.53 mm ± 0.07; 5000 cyc.: 0.63° ± 0.18, 0.79 mm ± 0.13), with B: p = 0.02, T: p = 0.04. Relative movements for medial bending were not significantly different between the two constructs. Cycles to failure (criterion 1 mm axial translation) differed significantly between LAP-LCP (19,519 ± 1,758) and cerclage-LCP (11,265 ± 2,472), with p = 0.035.

Conclusions

Biomechanically, the LAP-LCP construct improves proximal fixation of periprosthetic fractures compared to the cerclage-LCP construct.     

Cool Mist Irrigation Improves Heat Dissipation during Surgical Bone Drilling

Objective High-speed drilling generates heat in small cavities and may pose a risk for neurovascular tissues. We hypothesize that a continuous pressurized cold mist could be an alternative approach for better cooling during drilling of bone to access cranial lesions. This study aims to examine this idea experimentally. Design Ex-vivo drilling tests with controlled speed, feed, and depth were performed on cortical bone samples. Thermocouples were embedded underneath the drilling path to compare the temperature rises under mist cooling (at 3°C, < 300 mL/h) and flood irrigation (at 22°C, > 800 mL/h). Results A significant difference exists between these two systems (p value < 0.05). The measured temperature was ∼ 4°C lower for mist cooling than for flood irrigation, even with less than a third of the flow rate. Conclusion Experimental data indicate the capability of mist cooling to reduce heat generation while simultaneously enabling flow reduction and targeted cooling. An improved field of view in an extremely narrow access corridor may be achieved with this technology.     

Extra-articular dorsal closing-wedge osteotomy to treat late-stage Freiberg disease using polyblend sutures: technical tips and clinical results

Purpose

The purpose of this study was to evaluate the clinical outcomes regarding the dorsal wedge osteotomy fixed using a polyblend suture and describe the usefulness of this fixation method for the treatment of Freiberg disease.

Methods

The subjects consisted of 13 feet from 13 cases suffering from Freiberg disease that underwent extra-articular dorsal closing-wedge osteotomy using a polyblend suture. The average age was 31.7 (range 13–72) years. The average follow-up period was 17 (range 14–24) months. Regarding image findings, time to bone union and metatarsal shortening was reviewed. The investigation was carried out using the range of motion (ROM), visual analog scale (VAS), and Japanese Society of the Surgery of Foot lesser toe scale (JSSF score) in the MTP joint before surgery and at the latest follow-up.

Results

Calluses under the metatarsal head were not observed in any cases. The mean metatarsal shortening was 2.33 ± 2.07 mm at follow-up. The bone union required an average of 8.4 ± 0.8 weeks. The average ROM of dorsal flexion improved from 37.2 ± 5.3° before surgery to 73.6 ± 9.9° at latest follow-up (p < 0.0001). The average ROM of plantar flexion improved from 16.0 ± 10.1° before surgery to 19.5 ± 8.6° at latest follow-up (p = 0.35). The average VAS significantly improved from 75.3 ± 8.5 before surgery to 4.9 ± 4.2 at latest follow-up (p < 0.0001). The average JSSF score significantly improved from 67.3 ± 9.4 points before surgery to 98.8 ± 3.0 points at the latest follow-up (p < 0.0001).

Conclusion

Extra-articular dorsal closing-wedge osteotomy using a polyblend suture was carried out to treat Freiberg disease. The bone union was observed in all cases with improved clinical results. Fixation using a polyblend suture was considered to be useful.     

Prosthetic radial head stem pull-out as a mode of failure: a biomechanical study

Purpose

Press-fit cementless radial head implant longevity relies on adequate bone ingrowth. Failed implant osseointegration remains a clinical concern and has been shown to lead to prosthetic failure. The purpose of this study was to test the hypothesis that implants with sufficient initial press-fit stability would be less likely to fail due to implant pull-out, as demonstrated by an increasing amount of energy required to remove the prosthesis from the canal.

Methods

Ten cadaveric radii were implanted with five sizes (6–10 mm in 1-mm increments) of grit-blasted, cementless radial head stems. A customised slap hammer was used to measure the energy required to remove each stem. Stem-bone micromotion was also measured.

Results

The suboptimally sized stem (Max − 1) (i.e. 1 mm undersized) required less energy (0.5 ± 0 J) to pull out than the optimally sized stem (Max) (1.7 ± 0.3 J) (p = 0.008). The optimally sized stem demonstrated greater initial stability (45 ± 7 μm) than the suboptimally sized stem (79 ± 12 μm) (p = 0.004).

Conclusions

This investigation demonstrates the importance of obtaining adequate press-fit stability for the prevention of radial head stem pull-out failure. These data add to the relatively scant knowledge in the literature regarding radial head biomechanics. The energy required to remove a prosthetic radial head ingrowth stem decreases in conjunction with diameter. The use of an inadequately sized stem increases the stem’s micromotion as well as the risk of prosthetic loosening due to pull-out.     

Thermal osteonecrosis and bone drilling parameters revisited

Introduction During the drilling of the bone, the temperature could increase above 47°C and cause irreversible osteonecrosis. The result is weakened contact of implants with bone and possible loss of rigid fixation. The aim of this study was to find an optimal condition where the increase in bone temperature during bone drilling process would be minimal. Materials and methods Influence of different drill parameters was evaluated on the increase of bone temperature. Drill diameters were 2.5, 3.2 and 4.5 mm; drill speed 188, 462, 1,140 and 1,820 rpm; feed-rate 24, 56, 84 and 196 mm/min; drill point angle 80°, 100° and 120° and external irrigation with water of 26°C. Results Combinations of drill speed and drill diameter with the use of external irrigation produced temperatures far below critical. Without external irrigation, temperature values for the same combination of parameters ranged 31.4–55.5°C. Temperatures above critical were recorded using 4.5 mm drill with higher drill speeds (1,140 and 1,820 rpm). There was no statistical significance of different drill point angles on the increase or decrease of bone temperature. The higher the feed-rate the lower the increase of bone temperature. Conclusions The external irrigation is the most important cooling factor. With all combinations of parameters used, external irrigation maintained the bone temperature below 47°C. The increase in drill diameter and drill speed caused increase in bone temperature. The changes in drill point angle did not show significant influence in the increase of the bone temperature. With the increase in feed-rate, increase in bone temperature is lower.     

The Lyon’s sulcus-deepening trochleoplasty in previous unsuccessful patellofemoral surgery

Purpose

Trochleoplasty is a relatively rare operation with few published results and it remains a technically demanding procedure which requires careful patient selection. The ideal candidate for surgery remains to be elucidated, and some authors consider it as a good revision option in cases of previous unsuccessful operations for persisting patellar dislocation with underlying trochlear dysplasia. The purpose of this study is to record the results from the application of sulcus-deepening trochleoplasty in patients with trochlear dysplasia and previous unsuccessful surgery for patellar dislocation.

Methods

Twenty-two patients (24 knees) were operated upon during the period 9/1993–9/2006; they had undergone surgery for patellofemoral instability and had persistent patellar dislocation, and were followed-up for a mean of 66 months (24–191). Trochleoplasty was performed in all patients using the same technique and rehabilitation protocol. Additional soft-tissue and bony operations were performed in every case.

Results

Of all cases, 29.1 % had type B and 70.9 % had type D trochlear dysplasia. After trochleoplasty, no patient had a patellar re-dislocation up to the last follow-up. Pain decreased in 72 % and the apprehension sign was negative in 75 % of the cases (p < 0.01). Sulcus angle decreased from 153° ± 14° to 141° ± 10° (p < 0.01), TT-TG distance decreased from 16 ± 6 mm to 12 ± 2 mm (p < 0.001), and patellar tilt decreased from 31° ± 14° to 11° ± 8° (p < 0.0001). Mean pre-operative Kujala score was 44 (25–73) and at the latest follow-up it increased to 81 (53–100), (p < 0.001). At the time of final follow-up, there was no case of patellofemoral arthritis.

Conclusions

Trochlear dysplasia is a key factor in the treatment of recurrent patellar dislocation and its correction could be included in the surgical options. Sulcus-deepening trochleoplasty is an acceptable revision option for the surgical treatment of patients with persisting patellar dislocation and high-grade trochlear dysplasia.     

Does total hip arthroplasty restore native hip anatomy? Three-dimensional reconstruction analysis

Purpose

Component orientations and positions in total hip arthroplasty (THA) are important parameters in restoring hip function. However, measurements using plain radiographs and 2D computed tomography (CT) slices are affected by patient position during imaging. This study used 3D CT to determine whether contemporary THA restores native hip geometry.

Methods

Fourteen patients with unilateral THA underwent CT scan for 3D hip reconstruction. Hip models of the nonoperated side were mirrored with the implanted side to quantify the differences in hip geometry between sides.

Results

The study demonstrated that combined hip anteversion (sum of acetabular and femoral anteversion) and vertical hip offset significantly increased by 25.3° ± 29.3° (range, −25.7° to 55.9°, p = 0.003) and 4.1 ± 4.7 mm (range, −7.1 to 9.8 mm, p = 0.009) in THAs.

Conclusions

These data suggest that hip anatomy is not fully restored following THA compared with the contralateral native hip.     

Heat caused by drilling cortical bone: Temperature measured in vivo in patients and animals

In vivo temperature measurements were performed at drilling in the femoral cortex of the rabbit, dog and man. In the clinical study the bone temperature was measured at fixation of a Richards plate to stabilize a pertrochanteric fracture. With a drill speed of around 20 000 rpm and saline cooling, temperatures of 40°C in rabbits, 56°C in dogs and 89°C in patients were recorded at a distance of 0.5 mm from the periphery of the drill hole. The difference in temperature between the animal and clinical studies was mainly attributed to the difference in cortical thickness between the species. When drilling straight through the canine femur from the lateral to the medial side, a 9°C higher temperature was measured in the remote, medial cortex compared to that recorded in the lateral cortex. This difference arose because it is difficult for the cooling agent to reach the medial cortex. The results of the present study indicate that temperatures measured in animal experiments are not applicable to the clinical situation where very high temperatures may arise on drilling in cortical bone, even if saline cooling is used.     

A distal femoral supra-condylar plate: biomechanical comparison with condylar plate and first clinical application for treatment of supracondylar fracture

Purpose

An anatomical supra-condylar plate is designed and analysed by biomechanical testing.

Methods

The biomechanical properties of the supra-condylar and condylar plate were compared in six matched pairs of cadaveric femurs. A transverse osteotomy gap was created to simulate an OTA/AO type A3 supracondylar fracture. The left and right specimens were fitted with supra-condylar and condylar plate, respectively. Nondestructive axial compression, three-point bending and torsion tests were performed, and the peak load of the bone-implant construction was measured. The fracture site suitable for supra-condylar plate application and its correlation with femoral length were calculated. The gender influence on it was also discussed.

Results

The difference of stiffness between the supra-condylar and condyle groups were not significant (P > 0.05) at 363.4 and 362.5 N/mm for compression, 229.5 and 237.6 N/mm in the sagittal plane and 195.5 and 188.4 N/mm in the coronal plane for three-point bending, and 7.5 and 7.9 Nm/deg for axial torsion, respectively. The peak load was 4438 ± 136.15 N and 5215 ± 174.33 N, respectively, for the two groups. The average extent of the fracture site suitable for the application of the supra-condylar plate was 70.86 ± 4.61 mm. The femoral length and gender showed no influence on it.

Conclusion

Despite the limited bone contact area provided by the supra-condylar plate, its construct stiffness is comparable to the condylar plate. The supra-condylar plate can be used to treat carefully-selected extra-articular supracondylar fractures.     

Repair of segmental long-bone defects by stem cell concentrate augmented scaffolds: a clinical and positron emission tomography - computed tomography analysis

Purpose

Treating segmental long-bone defects remains a major challenge. For defects >3 cm, segmental transport represents the gold standard, even though the method is time consuming and afflicted with several complications. The aim of this study was to evaluate healing of such defects after grafting an osteogenic scaffold previously seeded with stem cell concentrate.

Methods

We evaluated five patients with segmental long-bone defects (3–14 cm) treated with bone marrow aspirate concentrates (BMAC) seeded onto a bovine xenogenous scaffold. The healing process was monitored by X-rays and positron emission tomography–computed tomography (PET-CT) three months after surgery.

Results

Centrifugation led to a concentration of leukocytes by factor 8.1 ± 7.5. Full weight bearing was achieved 11.3 ± 5.0 weeks after surgery. PET analysis showed an increased influx of fluoride by factor 8.3 ± 6.4 compared with the contralateral side (p < 0.01). Bone density in the cortical area was 75 ± 16 % of the contralateral side (p < 0.03). The patient with the largest defect sustained an implant failure in the distal femur and finally accomplished therapy by segmental transport. He also had the lowest uptake of fluoride of the patient collective (2.2-fold increase).

Conclusion

Stem cell concentrates can be an alternative to segmental bone transport. Further studies are needed to compare this method with autologous bone grafting and segmental transport.     

Atypical femoral fractures after anti-osteoporotic medication: a Korean multicenter study

Purpose

Increasing numbers of atypical femoral fractures have been reported among long-term bisphosphonate users. We evaluated clinical characteristics of atypical femoral fractures throughout Korean multicenter studies.

Methods

We retrospectively analysed the bone mineral density, prodromal symptoms before femoral fracture, and medication history of osteoporosis in 76 cases of atypical femoral fracture.

Results

The mean age of cases was 71.4 ± 8.8 (range, 43–89) years old. The mean follow-up period after the fracture operation was 24.5 ± 12.9 (range, 12–79) months. BMI was 23.2 ± 3.0 on average. The mean BMD of femur was −1.9 ± 1.4 (range, −4.8 to 1.3). Prodromal symptoms including thigh pain before femoral fracture appeared in 22 (28.9 %) of 76 patients. All patients included in the study used bisphosphonate. The duration of taking bisphosphonate before fracture was 36.8 ± 50.8 (one–204 months) months. Fifty-seven (75 %) of 76 patients were taking the medication for more than three years. Delayed union occurred in 43 (56.5 %) of 76 patients. Delayed union was defined as a fractured bone that did not completely heal within six months of injury. The group of having taken anti-osteoporotic medication for more than three years showed relatively longer union period compared to that for a shorter period medication group (4.8 ± 2.5 months vs 9.3 ± 3.7 months, p = 0.017). The delayed union developed in 43 (56.5 %) of 76 patients and showed a significantly higher incidence in the group with long-term therapy (five/43 vs 38/43, p = 0.021). The bilateral femoral fractures developed in 23 (30.2 %) of 76 patients and showed a high incidence in the group medicated more than three years (two/23 vs 21/23, p = 0.039).

Conclusions

The longer bisphosphonates are used, the more the cases of delayed union and the more frequent the development of bilateral fractures following unilateral fractures. With regard to the delayed union, the methods of the acceleration of fracture healing may be beneficial in atypical femoral fracture patients who had been receiving long-term bisphosphonates therapy. Careful observation is required for contra-lateral femurs due to a high incidence of bilateral atypical femoral fractures.     

Lateral tenodesis combined with anterior cruciate ligament reconstruction using a unique semitendinosus and gracilis transplant

Purpose

The aim of this study was to assess the anatomical results, functional results and the incidence of arthritis of a mixed intra- and extra-articular hamstring tendon based reconstruction for anterior instability of the knee.

Methods

This retrospective study consists of 100 knees in 99 patients (22 female and 77 male) operated upon between November 2003 and March 2006. The average age was 29.7 ± 10.4 years and the average interval between injury and surgery was 26.6 ± 41.8 months (2–240). In our technique, the semitendinosus and gracilis tendons were left attached to the tibia and by means of a lateral transcondylar tunnel posterior and inferior to the proximal attachment of the lateral collateral ligament were passed around the knee before being sutured to the fascia lata at the level of Gerdy’s tubercle.

Results

Sixty-eight knees were re-examined at an average follow-up of 76 ± 12 months. The average differential anterior drawer test at the last review was 2.5 ± 3.4 mm (p < 0.0001). Of the patients 75 % had a negative pivot shift test, 21 % a gliding test and 4 % a clear positive test (p < 0.0001); 84 % of patients had an International Knee Documentation Committee (IKDC) score rated A or B. The average IKDC subjective score was 90 ± 9 (60–100).

Conclusions

Mixed intra- and extra-articular reconstructions using hamstring grafts allow the knee to be stabilised in the sagittal plane and the rotatory instability to be controlled in the majority of cases. Only very minor progression of arthritic changes at an average 76 ± 12 months was seen.     

Thermal damage during humeral reaming in total shoulder resurfacing

Introduction:

Total shoulder resurfacing (TSR) provides a reliable solution for the treatment of glenohumeral arthritis. It confers a number of advantages over traditional joint replacement with stemmed humeral components, in terms of bone preservation and improved joint kinematics. This study aimed to determine if humeral reaming instruments produce a thermal insult to subchondral bone during TSR.

Patients and Methods:

This was tested in vivo on 13 patients (8 with rheumatoid arthritis and 5 with osteoarthritis) with a single reaming system and in vitro with three different humeral reaming systems on saw bone models. Real-time infrared thermal video imaging was used to assess the temperatures generated.

Results:

Synthes (Epoca) instruments generated average temperatures of 40.7°C (SD 0.9°C) in the rheumatoid group and 56.5°C (SD 0.87°C) in the osteoarthritis group (P = 0.001). Irrigation with room temperature saline cooled the humeral head to 30°C (SD 1.2°C). Saw bone analysis generated temperatures of 58.2°C (SD 0.79°C) in the Synthes (Epoca) 59.9°C (SD 0.81°C) in Biomet (Copeland) and 58.4°C (SD 0.88°C) in the Depuy Conservative Anatomic Prosthesis (CAP) reamers (P = 0.12).

Conclusion:

Humeral reaming with power driven instruments generates considerable temperatures both in vivo and in vitro. This paper demonstrates that a significant thermal effect beyond the 47°C threshold needed to induce osteonecrosis is observed with humeral reamers, with little variation seen between manufacturers. Irrigation with room temperature saline cools the reamed bone to physiological levels and should be performed regularly during this step in TSR.     

Cartilage repair of the knee with Hyalograft C:® Magnetic Resonance Imaging assessment of the glycosaminoglycan content at midterm

Purpose

The aim of this study was to assess the stability of the glycosaminoglycan (GAG) content in the long term after matrix-associated autologous chondrocyte transplantation (MACT) with Hyalograft C in the knee over a follow-up period of one year.

Methods

In this cross-sectional evaluation, 11 patients after MACT of the knee consented to delayed gadolinium-enhanced magnetic resonance imaging of cartilage (dGEMRIC) measurements. The mean post-operative interval before the first MR examination was 40.6 ± 22.0 months, and the second MR examination was carried out after another 12 months. The Lysholm score was assessed for clinical evaluation. Quantitative T1 measurements after intravenous negatively charged MR contrast agent administration were performed. Global post-contrast T1 of the reference cartilage and the repair tissue and a relative post-contrast T1 value were calculated.

Results

The Lysholm score improved significantly from 59.8 ± 12.9 at baseline to 86.1 ± 15.7 at the second visit (p < 0.01). The mean global T1 of the repair tissue (1st visit 581.3 ± 126.4 ms; 2nd visit 684.1 ± 169.9 ms; p = 0.104) and the mean relative T1 value showed stable results over one year (1st visit 0.81 ± 0.28; 2nd visit 0.76 ± 0.32; p = 0.4).

Conclusions

The study demonstrated stable glycosaminoglycan content of the repair tissue after MACT at midterm.     

Gait knee kinematic alterations in medial osteoarthritis: three dimensional assessment

Purpose

Although kinematic changes in the sagittal plane of the osteoarthritic knee (OA) have been elucidated, very few studies have analysed changes in the frontal and horizontal planes. Therefore, the aim of this study was to investigate in vivo 3D knee kinematics during walking in patients wth knee OA.

Methods

Thirty patients with medial knee OA and a control group of similarly aged individuals were prospectively collected for this study. All participants were assessed with KneeKG^TM system while walking on a treadmill at a self-selected speed. In each trial, we calculated the angular displacment of flexion/extension, abduction/adduction and external/internal tibial rotation. Statistical analysis was performed to determine differences between the knee OA group and the control group.

Results

Patients with knee OA had reduced extension during the stance phase (p < 0.05; 8.5° and 4.4°, OA and control group, respectively) and reduced flexion during pushoff and initial swing phase (p  < 0.05; 41.9° and 49.4°, respectively). Adduction angle was consistently greater for OA patients (p  < 0.05; 3.4° and −0.9°, respectively). Frontal laxity for OA patients was positively correlated with varus deformity (r = 0.42, p < 0.05). There was a significant difference (p)  < 0.05 in tibial rotation during the midstance phase; OA patients retained a neutral position (−0.4°), while the control group presented internal tibial rotation (−2.2°).

Conclusion

Weight-bearing kinematics in medial OA knees differs from that of normal knees. The knee OA group showed an altered “screw-home” mechanism by decreased excursion in sagittal and axial tibial rotation and posterior tibial translation.