Biodegradable Pins Research Articles

Evaluation of surgical fixation methods for the implantation of melt electrowriting-reinforced hyaluronic acid hydrogel composites in porcine cartilage defects.

The surgical repair of articular cartilage remains an ongoing challenge in orthopedics. Tissue engineering is a promising approach to treat cartilage defects; however, scaffolds must (i) possess the requisite material properties to support neocartilage formation, (ii) exhibit sufficient mechanical integrity for handling during implantation, and (iii) be reliably fixed within cartilage defects during surgery. In this study, we demonstrate the reinforcement of soft norbornene-modified hyaluronic acid (NorHA) hydrogels via the melt electrowriting (MEW) of polycaprolactone to fabricate composite scaffolds that support encapsulated porcine mesenchymal stromal cell (pMSC, three donors) chondrogenesis and cartilage formation and exhibit mechanical properties suitable for handling during implantation. Thereafter, acellular MEW-NorHA composites or MEW-NorHA composites with encapsulated pMSCs and precultured for 28 days were implanted in full-thickness cartilage defects in porcine knees using either bioresorbable pins or fibrin glue to assess surgical fixation methods. Fixation of composites with either biodegradable pins or fibrin glue ensured implant retention in most cases (80%); however, defects treated with pinned composites exhibited more subchondral bone remodeling and inferior cartilage repair, as evidenced by micro-computed tomography (micro-CT) and safranin O/fast green staining, respectively, when compared to defects treated with glued composites. Interestingly, no differences in repair tissue were observed between acellular and cellularized implants. Additional work is required to assess the full potential of these scaffolds for cartilage repair. However, these results suggest that future approaches for cartilage repair with MEW-reinforced hydrogels should be carefully evaluated with regard to their fixation approach for construct retention and surrounding cartilage tissue damage.

Is implant choice associated with fixation strength for displaced radial neck fracture: a network meta-analysis of biomechanical studies

The multitude of fixation options for radial neck fractures, such as pins, screws, biodegradable pins and screws, locking plates, and blade plates, has led to a lack of consensus on the optimal implant choice and associated biomechanical properties. This study aims to evaluate the biomechanical strength of various fixation constructs in axial, sagittal, and torsional loading directions. We included biomechanical studies comparing different interventions, such as cross/parallel screws, nonlocking plates with or without augmented screws, fixed angle devices (T or anatomic locking plates or blade plates), and cross pins. A systematic search of MEDLINE (Ovid), Embase, Scopus, and CINAHL EBSCO databases was conducted on September 26th, 2022. Data extraction was carried out by one author and verified by another. A network meta-analysis (NMA) was conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-analyses guidelines. Primary outcomes encompassed axial, bending, and torsional stiffness, while the secondary outcome was bending load to failure. Effect sizes were calculated for continuous outcomes, and relative treatment ranking was measured using the surface under the cumulative ranking curve (SUCRA). Our analysis encompassed eight studies, incorporating 172 specimens. The findings indicated that fixed angle constructs, specifically the anatomic locking plate, demonstrated superior axial stiffness (mean difference [MD]: 23.59 N/mm; 95% CI 8.12–39.06) in comparison to the cross screw. Additionally, the blade plate construct excelled in bending stiffness (MD: 32.37 N/mm; 95% CI − 47.37 to 112.11) relative to the cross screw construct, while the cross-screw construct proved to be the most robust in terms of bending load failure. The parallel screw construct performed optimally in torsional stiffness (MD: 139.39 Nm/degree; 95% CI 0.79–277.98) when compared to the cross screw construct. Lastly, the nonlocking plate, locking T plate, and cross-pin constructs were found to be inferior in most respects to alternative interventions. The NMA indicated that fixed angle devices (blade plate and anatomic locking plate) and screw fixations may exhibit enhanced biomechanical strength in axial and bending directions, whereas cross screws demonstrated reduced torsional stability in comparison to parallel screws. It is imperative for clinicians to consider the application of these findings in constraining forces across various directions during early range of motion exercises, taking into account the distinct biomechanical properties of the respective implants.

Biodegradable fixation pins for interphalangeal joint arthrodesis in lesser toe deformity and fracture correction – A retrospective follow-up of 31 toes

Lesser toe deformities are commonly surgically treated with interphalangeal joint arthrodesis using different internal fixation implants with good results. There are few studies reporting the results of the use of bioabsorbable implants. The aim of this study was to investigate the clinical and radiological outcomes of lesser toe interphalangeal joint arthrodesis using a novel biodegradable pin as fixation method. Consecutive patients operated by proximal (PIPJ) or distal interphalangeal joint (DIPJ) arthrodesis using the Inion FreedomPin™ (Inion Oy, Tampere, Finland) with a minimum of 12 months of follow-up were retrospectively evaluated both clinically and radiologically. 21 patients (age 34–78, median 60 years) with 24 feet and 31 toes were available with a median follow-up of 26 (range 12–40) months. Clinical alignment was good in all but one toe. There were no complications and patient satisfaction was high. The radiological alignment was corrected in 25, partially corrected in five, and not corrected in one toe. A complete radiological bony fusion was detected in 25 (81%), partial in one (3%), and no fusion in five (16%) toes. In conclusion, the Inion FreedomPin™ bioabsorbable pin had clinically and radiologically favourable outcome for lesser toe interphalangeal joint arthrodesis.

Percutaneous Correction Surgery of Hammer Toes with Biodegradable Pins

Category:Lesser Toes; Midfoot/ForefootIntroduction/Purpose:The standard treatment for deformities in lesser toes is proximal interphalangeal arthrodesis with Kirschner wires. It is relatively inexpensive but complications have been described such as infection, recurrences and misalignment. New devices were developed, among them biodegradable pins avoid the need for withdrawal and exposure to the outside. The objective of this study was to describe the clinical and radiological results one year after surgery in a group of patients with a diagnosis of rigid hammer toes, who underwent percutaneous surgical correction with a biodegradable pin.Methods:Methods: We present a retrospective study in a consecutive series of cases with a diagnosis of hammer toe operated between January 2016 and December 2018. Patients older than 18 years of age who underwent a percutaneous proximal interphalangeal arthrodesis, with a biodegradable pin, were included. The patients were asked through a survey to rate the results obtained with the intervention (excellent, very good, good, fair and bad). loss of contact with the ground was evaluated with podobarography. The patients were evaluated with weightbearing X rays to assess interphalangeal alignment and consolidation. We used the AOFAS scale to assess clinical results, preoperatively and one year after surgery. Postoperative complications, infection, wound dehiscence, rupture of osteosynthesis material, loss of correction were also evaluated.Results:117 patients were identified, 23 (16%) underwent bilateral surgery (140 feet), with a total of 220 lesser toes who underwent proximal interphalangeal arthrodesis stabilized with percutaneously biodegradable pin. 50% had a minimum follow-up of 1 year. The pre-surgical AOFAS of 52 improved to 95 points in the postoperative period. In 96 (43.63%) fingers, an F1 base osteotomy was performed to correct the alignment in the coronal plane. We observed pseudo osteoarthritis in 5% of the toes but with good alignment. We observed 6% of floating fingers, the pin was removed in 5 fingers; without loss of correction. In 1.36% cases it migrated early, causing a recurrence of the lesion. Patient satisfaction was excellent or very good in 79 %.Conclusion:According to our serie results, we consider that percutaneous technique with biodegradable pins manages to maintain adequate alignment and a consolidation rate both in radiological and clinical results with good patient satisfaction. No infection case was reported. We found a low rate of biodegradable pin removal. For its part, the biodegradable plug allows osteotomies to be performed with the implant already in place, it does not require routine removal of the implant, reducing the need for a second intervention.

Biodegradable pins for lateral condylar fracture of the humerus with an early delayed presentation in children: a retrospective study of biodegradable pin vs. Kirschner wire

BackgroundThe clinical outcome of open reduction and internal fixation (ORIF) for delayed lateral condylar fracture of the humerus (LCFH) varies in different studies, but ORIF for LCFH with an early-delayed presentation usually resulted in significant improvement of elbow function. Early delayed presentation is defined as a period of 3 to 12 weeks from the injury. This study aims to compare the clinical outcomes of biodegradable pin (BP) vs. Kirschner wire (KW) in the treatment of LCFH with an early delayed presentation.MethodsLCFH with an early-delayed presentation treated with KW or BP were retrospectively reviewed in our hospital. The patients were divided into two groups KW (n = 17) and BP group (n = 26). Baseline information, including sex, age, operative side, duration from injury to surgery, and implant choice, was reviewed. Radiographs and medical records were collected from the Hospital Database.ResultsIn all, 17 patients (male/female, 9/8) in KW and 26 patients (male/female,13/13) in the BP group were included. The age showed no statistically significant difference between the KW (52.3 ± 10.2, month) and the BP (56.1 ± 10.7, month), (P = 0.258). At the last follow-up, there existed no statistically significant difference between the two groups concerning Baumann’s angle (P = 0.272) and carrying angle (P = 0.911). The MEPS at the last follow-up was better in the KW group (91.1 ± 2.7) than the BP group (89.2 ± 3.0), (P = 0.048). There was no case of nonunion or malunion in both groups. The incidence of fishtail deformity was (8/17, 47.1%) in KW and (13/26, 50%) in the BP group. The incidence of lateral prominence was (5/17, 29.4%) in the KW and (7/26, 26.9%) in the BP group. Furthermore, the incidence of implant prominence was higher in KW (12/17, 70.6%) than BP (0) (P < 0.001).ConclusionOpen reduction and internal fixation for LCFH with an early-delayed presentation produced satisfactory outcomes. Biodegradable pin is a good alternative to Kirschner wire, with comparable clinical outcomes.

Mechanical and degradative properties of PLDLA biodegradable pins with bioactive glass fibers in a beagle model

The present study aimed to evaluate the mechanical and degradative properties of poly(L-co-D,L-lactic acid)/silicate bioactive glass fibers (PLDLA/SGFs) composite pins in vivo. Both PLDLA and PLDLA/SGFs pins were inserted into the erector spinae muscles and femurs of beagle dogs and were harvested 6, 12, 16, 26, 52, 78, and 104 weeks after insertion. Bone formation around the pins was evaluated by micro-computed tomography. Mechanical properties were measured by the shear strength test. Thermogravimetric analysis, differential scanning calorimetry, and gel permeation chromatography were used to assess the degradation of these materials. The surface and cross-sectional morphology of both pins were observed using a scanning electron microscope. The experimental data demonstrated that PLDLA/SGFs pins can support new bone formation due to the influence of bioactive glass fibers. PLDLA/SGFs composite pins had higher initial shear strength and were relatively stable for at least 26 weeks. The addition of bioactive glass fibers accelerated the degradation rate of the composite pins. Thus, PLDLA/SGFs composite pins have promising potential for bone fixation applications.

Percutaneous pinning for treating distal radial fractures in adults.

Background Fracture of the distal radius is a common clinical problem. A key method of surgical fixation is percutaneous pinning, involving the insertion of wires through the skin to stabilise the fracture. Objectives To evaluate the evidence from randomised controlled trials for the use of percutaneous pinning for fractures of the distal radius in adults. Search methods We searched the Cochrane Bone, Joint and Muscle Trauma Group Specialised Register (September 2006), the Cochrane Central Register of Controlled Trials, MEDLINE, EMBASE and other databases, conference proceedings and reference lists of articles. No language restrictions were applied. Selection criteria Randomised or quasi-randomised controlled clinical trials involving adults with a fracture of the distal radius, which compared percutaneous pinning with conservative treatment, or different aspects of percutaneous pinning. Data collection and analysis Two authors independently assessed and extracted data from the included trials. Some pooling of data was undertaken for one comparison. Main results Thirteen trials, involving 940 generally older adults with dorsally displaced and potentially or evidently unstable distal radial fractures, were included. Methodological weaknesses among these trials included lack of allocation concealment and inadequate outcome assessment. Factors affecting the applicability of trial evidence included inconsistent fracture classification, variations in outcome assessment and incomplete reporting. Six heterogeneous trials compared percutaneous pinning with plaster cast immobilisation. Across-fracture pinning, used in five trials, was associated with improved anatomical outcome and generally minor complications. There was some indication of similar or improved function in the pinning group. One quasi-randomised trial found an excess of complications after Kapandji pinning. Three trials compared different methods of pinning. Two trials found a higher incidence of complications after Kapandji fixation compared with two methods of across-fracture fixation. The third trial provided inadequate evidence for modified Kapandji fixation versus Willenegger fixation. Two small trials comparing biodegradable pins versus metal pins found a significant excess of complications associated with biodegradable material. Two small trials compared plaster cast immobilisation for one week versus for six weeks after surgery. One trial found duration of immobilisation after trans-styloid fixation did not have a significant effect on outcome. More complications occurred in the early mobilisation group after Kapandji pinning in the second trial. Authors' conclusions Though there is some evidence to support its use, the precise role and methods of percutaneous pinning are not established. The higher rates of complications with Kapandji pinning and biodegradable materials casts some doubt on their general use.

Surgical interventions for treating fractures of the olecranon in adults.

Surgical interventions for treating fractures of the olecranon in adults.

Surgical interventions for treating radial head fractures in adults

Radial head fractures are the most common type of elbow fracture and can severely affect the function of the elbow. There is uncertainty and controversy about when surgery is indicated as well as what type of surgical intervention is best. To assess the effects of surgical interventions for treating radial head fractures in adults. We aimed to compare surgical versus non-surgical treatment, and different methods of surgical intervention. We searched the Cochrane Bone, Joint and Muscle Trauma Group Specialised Register (May 2012), the Cochrane Central Register of Controlled Trials (The Cochrane Library; 2012 Issue 4), MEDLINE (1946 to May 2012), EMBASE (1980 to 2012 Week 19) and trial registers (November 2011). No language restrictions were applied. All randomised and quasi-randomised controlled trials evaluating surgical interventions for treating radial head fractures. Two review authors independently selected trials, assessed risk of bias and extracted data. Where appropriate, results were pooled. We included three randomised controlled trials, involving a total of 251 participants. All three trials were at high risk of performance bias reflecting the fact that surgeons could not be blinded. One trial was at low risk of selection bias but was undermined by a high attrition bias, in part resulting from post-randomisation exclusions. There were incomplete details of methodology for the other two trials, which usually resulted in unclear risk of bias judgements.Two trials compared radial head replacement with open reduction and internal fixation (ORIF) for treating Mason type III radial head fractures. The trial authors reported outcomes at a mean of 2.8 years and 15 months respectively. There were significant differences between the two groups in favour of radial head replacement in the Broberg and Morrey elbow scores (92.1 versus 72.4, mean difference (MD) 19.70; 95% confidence interval (CI) 15.64 to 23.76; one trial, 45 participants), excellent or good Broberg and Morrey elbow scores (33/36 versus 16/31, risk ratio (RR) 1.88; 95% CI 1.27 to 2.77; two trials), and overall adverse events (6/36 versus 15/31, RR 0.33; 95% CI 0.14 to 0.77; two trials). No statistically significant difference was found between the two groups in any of the reported individual adverse events.One trial compared biodegradable pins with standard metal screws in treating radial head fractures of AO-classification 21 B2. The two types of fixation devices yielded similar results, with no significant between-group differences in the Broberg and Morrey scores (93.3 versus 90.9, MD 2.40; 95% CI -0.10 to 4.90), excellent or good Broberg and Morrey elbow scores (72/74 versus 56/61, RR 1.06; 95% CI 0.97 to 1.15), and adverse events (13/82 versus 16/82, RR 0.81; 95% CI 0.42 to 1.58) at two-year follow-up. Only tentative conclusions can be drawn from the available evidence in this review. Compared with ORIF, there was some evidence that radial head replacement had better elbow function and fewer adverse events for Mason type III radial head fractures in the short term. However, the evidence is of low quality and it is unknown whether these results would apply in the longer term or more generally. Using biodegradable implants may be as good as metallic implants for fixation of some usually more stable fractures but more evidence is needed to confirm this. There is a need for good quality evidence for addressing the areas of uncertainty for the surgical treatment of radial head fractures.

Clinical results after different operative treatment methods of radial head and neck fractures: A systematic review and meta-analysis of clinical outcome

IntroductionThere is no consensus on optimal treatment strategy for Mason type II–IV fractures. Most recommendations are based upon experts’ opinion. MethodsAn OVID-based literature search were performed to identify studies on surgical treatment of radial head and neck fracture. Specific focus was placed on extracting data describing clinical efficacy and outcome by using the Mason classification and including elbow function scores.A total of 841 clinical studies were identified describing in total the clinical follow-up of 1264 patients. ResultsFor type II radial head and neck fractures the significant best treatment option seems to be ORIF with an overall success rate of 98% by using screws or biodegradable (polylactide) pins.ORIF with a success rate of 92% shows the best results in the treatment of type III fractures and seem to be better than resection and implantation of a prosthesis. For this fracture type the ORIF with screws (96%), biodegradable (polylactide) pins (88%) and plates (83%) showed the best results.In the treatment of type IV fractures similar results could be found with a tendency of the best results after ORIF followed by resection and implantation of a prosthesis.If a prosthesis was implanted, the primary implantation seems to be associated with a better outcome after type III (87%) and IV (82%) fractures compared to the results after a secondary implantation. DiscussionRecommendations for surgical treatment of radial head and neck fractures according to the Mason classification can now be given with the best available evidence.Level of evidence: IV

High incidence of tunnel widening after anterior cruciate ligament reconstruction with transtibial femoral tunnel placement

This study evaluated the incidence, amount, morphology and clinical significance of bone tunnel widening (TW) at a mean 5-year period after anterior cruciate ligament reconstruction (ACLR) with a transtibial drilling technique. Fifty-nine patients undergoing primary ACLR using quadrupled hamstring autografts, biodegradable transfemoral pins for femoral-sided and 2-mm oversized interference screws for tibial-sided graft fixation were followed up at a mean 61 months postoperatively. Patients were examined clinically and by MRI. Tunnel cross-sectional areas (CSA) were related to drill diameters, which were significantly correlated with radiographic tunnel sizes. Tunnel morphologies were assessed and their positions determined using an anatomical coordinate system. CSA had more than doubled in all segments measured (p < 0.0001) except at the femoral notch level. Greatest CSA increases were found at the femoral graft suspension point (122 %) and at the central tibial tunnel segment (134 %). 54 (92) and 56 (95 %) patients had significant TW, i.e., CSA increase of more than 50 %, in at least one tunnel segment femorally and tibially. Four different tunnel morphologies were observed, of which the linear type was most often encountered on either side. Mean side-to-side difference in anterior-posterior laxity was 1.0 ± 1.4 mm, while Lysholm, IKDC and Tegner activity scores were 90 ± 12, 84 ± 15 and 4 (1-9); clinical outcomes were not found to be correlated with tunnel sizes and morphologies as were tunnel positions and tunnel sizes. This study demonstrates that considerable TW occurs in virtually all patients in the mid term after ACLR using a transtibial drilling technique with 'high' femoral tunnel positions. Yet, neither amount nor morphology or tunnel position does affect knee stability or function.

In Vivo Tissue Response to Ultrasound Assisted Application of Biodegradable Pins into Cortical and Cancellous Bone Structures: A Histological and Densitometric Analysis in Rabbits

In orthopaedic traumatology biodegradable pins are increasingly used for fixation of small bone fragments. In the present study, the ultrasound-assisted anchoring technique (SonicFusion technique), a osteosynthesis method being recently introduced in cranial applications, in which ultrasonic energy is used to insert and anchor polymer pins in bone, was compared with the conventional pin application procedure. The aim of the present study was to assess the short and long term thermal impact of two different ultrasonic energy levels on different bone structures in the distal medial femur of rabbits. The treatment groups consisted of customized polylactide pins applied at a low and a high energy level, the Reference Control and a Negative Control. The thermal effect on bone tissues was evaluated by means of qualitative and semi-quantitative histology and micro-computerized tomography. Five days following surgery, all implant sites showed no tissue damage but normal signs of early ongoing tissue repair. Enhancing the energy level by about 30% had no significant impact on the tissue response. At 4 weeks after surgery test sites covered by ultrasound-aided implantation showed a significantly enhanced bone/implant contact as compared to pins applied by conventional application. In conclusion, the ultrasound assisted anchoring technique not only did not impair bone regeneration, but even improved implant integration.

Arthroscopic Fixation of Matrix-Associated Autologous Chondrocyte Implantation: Importance of Fixation Pin Angle on Joint Compression Forces

The aim of the study was to investigate the effect of pin fixation perpendicular and 30° tilted to the matrix surface on the joint compression forces. In a porcine knee model, joint compression forces were recorded with a digital pressure sensor above the medial meniscus and with axial compression of 100 N by use of a material testing machine. The forces were recorded for an intact femoral condyle, as well as a standardized cartilage defect of 25 × 20 mm, after matrix-associated autologous chondrocyte implantation (m-ACI) (BioSeed C; Biotissue Technologies, Freiburg, Germany), fixed by use of a conventional suture technique and pin fixation with a biodegradable pin perpendicular and 30° tilted to the matrix surface. In knees with cartilage defects, the peak compression forces (mean, 824 kPa) were significantly increased compared with the intact knee joint (564 kPa). After m-ACI implantation with a chondral suture (581.3 kPa) and perpendicular pin fixation, the joint compression forces of the cartilage defect were significantly decreased (630.7 kPa). There were no significant differences compared with the intact knee. After 30° tilted pin insertion, mean joint compression forces were significantly increased (1,740 kPa). This study shows that after chondral suture and perpendicular pin fixation, there are no increased compression forces in the knee joint in comparison to an intact knee. Thirty degree tilted pin insertion contributes to increased joint compression forces. A tilted insertion during pin fixation in m-ACI should be avoided because it may lead to increased joint compression forces, especially after cartilage defect lesions on the tibial side.

Clinical benefit of SPECT/CT for follow-up of surgical treatment of osteochondritis dissecans

We present the case of a 17-year-old ice-hockey player, who complained about persistent left medial knee pain having undergone a refixation of a grade III osteochondritis dissecans with biodegradable pins, a reconstruction of the anterior cruciate ligament (ACL) and a medial meniscal repair 1year previously. Sequential MRIs performed 8 and 12months after surgery were inconclusive, and failed to show the insufficient integration of the osteochondral fragment. Combined single photon emission and conventional computerized tomography (SPECT/CT) clearly revealed the cause of the patient's persistent knee problems-the osteochondral fragment had not integrated. SPECT/CT may hold great clinical value for symptomatic patients who have previously undergone treatment for osteochondral lesions, and it should be considered as alternative diagnostic imaging modality.

Arthroscopic Implantation of a Matrix to Cover Large Chondral Defect During Microfracture

Microfracturing techniques have been reported to be successful cartilage-restoring treatment options in defects of smaller sizes. The success may be limited by the size of the defect and the shoulder of the intact surrounding cartilage. We report a new technique using a 3-dimensional matrix to cover large cartilage defects during microfracture healing. In contrast to autologous chondrocyte implantation techniques, this technique is a 1-stage procedure. The defect cover consists of a resorbable polymer felt and sodium hyaluronan to induce hemostasis and to protect the underlying tissue. After conventional microfracture, the defect size is determined with an intra-articular measuring device, and the matrix is sized and introduced with an arthroscopic grasp. Depending on the size of the defect, the 3-dimensional matrix is fixed with 1 or 2 biodegradable pins perpendicular to the surface. The combination of the common microfracture technique with the implantation of the matrix leads to complete defect filling with cartilaginous repair tissue and therefore improves cartilage regeneration in the defect. We conclude that the introduced technique may be helpful in large cartilage defects combining the benefit of microfracturing and avoidance of the increased morbidity of matrix-associated autologous chondrocyte implantation.

Quality of scaffold fixation in a human cadaver knee model

Newly developed regenerative cartilage interventions based on the application of 3D-scaffolds require a further evaluation of the surgical techniques involved. The present study compared four different scaffold fixation techniques [fibrin glue (FG), transosseous (TS) fixation, biodegradable pin (BP) fixation and continuous cartilage sutures (CS)] to implant a custom-printed porous PEOT/PBT1000/70/30 scaffold in a human cadaver knee model. After implantation, the knees were subjected to a vertically oriented loaded continuous passive motion (CPM) protocol. The fixation techniques were evaluated after 60 and a subsequent 150 motion cycles, focusing on area coverage, outline attachment and scaffold integrity. After the total of 210 cycles, also an endpoint fixation test was performed. The fixation techniques revealed marginal differences for area coverage and outline attachment after 60 and 150 cycles. The FG scored higher on scaffold integrity compared to TS (P<0.05) and CS (P=0.01). Endpoint fixation was highest for the CS, whereas FG showed a weak final fixation strength (P=0.01). This study showed that optimal fixation cannot be combined always with high scaffold integrity. Special attention devoted to scaffold properties in relation to the fixation technique may result in an improvement of scaffold fixation, and thus clinical cartilage regenerative approaches involving these scaffolds.

Bioresorbable Pins and Interference Screws for Fixation of Hamstring Tendon Grafts in Anterior Cruciate Ligament Reconstruction Surgery

Background Biodegradable cross-pins have been shown to provide higher failure loads than do screws for fixation of hamstring tendons under laboratory conditions. Purpose To compare the clinical results of biodegradable pins (RigidFix) and interference screws (BioCryl) for fixation of hamstring grafts in arthroscopically assisted anterior cruciate ligament reconstruction. Study Design Randomized controlled trial; Level of evidence, 1. Methods To test the hypothesis of a difference of 1.0 ± 1.2 mm in anterior knee laxity between the two fixation options, 54 patients were randomly assigned to groups via a block randomization scheme and sealed envelopes. All patients underwent standardized hamstring graft reconstruction and had similar postoperative aftercare by an accelerated rehabilitation protocol. Measures assessed at baseline and after 1 and 2 years of follow-up included (1) the side-to-side difference in anterior laxity (KT-1000 arthrometer), (2) Short Form 36 physical and mental component scores, and (3) the International Knee Documentation Committee form scores. Results After 1 and 2 years, 26 and 21 patients in the BioCryl group and 28 and 24 patients in the RigidFix group were available for follow-up examination. No significant difference was noted in instrumented anterior translation between BioCryl and RigidFix fixation: 1 year, 0.11 (95% CI, —0.60 to 0.82; P = .7537); 2 years, 0.33 (95% CI, —0.43 to 1.08 mm; P = .3849). Also, there were no significant differences in the mean physical and mental component scores and International Knee Documentation Committee form scores and in overall complication and surgical revision rates. A pin dislocation was classified as the sole procedure-specific serious adverse event. Conclusion Bioresorbable pins do not provide better clinical results than do resorbable interference screws for hamstring graft fixation in anterior cruciate ligament reconstruction surgery.

Successful return to work after surgical repair of fracture of the medial condyle of the distal femur in two working farm dogs

CASE HISTORY: A 5-year-old male Heading dog (working Collie) and a 2-year-old female Huntaway each presented with non-weight-bearing lameness of a hindlimb after jumping or falling with the leg trapped in a gate or motorbike carrier. CLINICAL FINDINGS: Pain and swelling were localised to the stifle, and radiographs revealed a fracture of the medial condyle of the distal femur in each case. DIAGNOSIS: Medial unicondylar, intra-articular fractures of the distal femur. CLINICAL RELEVANCE: Open reduction and internal fixation provided an excellent outcome in each case. Open reduction was achieved after elevation of the insertion of the medial collateral ligament from the proximal tibia. Both cases had severe tears to the caudal pole of the medial meniscus, requiring partial meniscectomy. Internal fixation was applied using either divergent K-wires and a biodegradable pin, or a lag-screw technique. The medial collateral ligament was reattached using a 3.5-mm cancellous screw and spiked washer. The therapeutic outcome, i.e. clinical result and return to work, was determined by gait assessment, physical examination, radiography, and an owner's questionnaire. Both working dogs became sound and successfully returned to full work within 6 months of surgery. One dog was subject to euthanasia due to unrelated disease one year after surgery, but the other dog was working fully at 2 years post-operatively; radiography showed osteoarthrosis (OA) but manipulation revealed near-normal range of motion and no loss of muscling.

Anterior cruciate ligament reconstruction using autografts and double biodegradable femoral cross-pin fixation: functional, radiographic and MRI outcome after 2-year minimum follow-up

Double biodegradable cross-pins are increasingly used for femoral fixation in arthroscopically assisted reconstruction of the anterior cruciate ligament (ACL). There are no studies combining functional outcome analysis, radiographs and magnetic resonance images (MRI) to evaluate this technique. The authors examined 45 patients after ACL reconstruction using double biodegradable femoral cross-pin fixation and biodegradable tibial interference screw fixation with a minimum follow-up of 24 months. Clinical evaluation included International Knee Documentation Committee (IKDC) and modified Lysholm score. Radiographic analysis included standard X-rays in anterior-posterior and lateral views and Telos stress device measurements. MRI was analyzed to obtain information about hardware, intra-articular graft, osseous graft-integration and cartilage. IKDC score revealed 28 (62.2%) patients with normal knee function (group A), 15 (33.3%) patients with nearly normal (group B) knee function and 2 (4.4%) patients with abnormal knee function (group C). The Lysholm score was 94.6 (+/-7.2) in the operated knee and 98.8 (+/-7.4) in the non-operated knee. Mean Telos stress device values were +4.6 (+/-2.6) in the operated and +3.9 (+/-2.4) in the non-operated knee. MRI showed an intact intra-articular graft in all but one patient. Complete femoral graft integration was seen in 88.9% and complete tibial graft integration in 86.7%. Biodegradable cross-pins were partially or fully visible in all patients. The biodegradable tibial interference screw was fully visible in 16 (35.6%) and partially visible in 20 (44.4%) patients. Thirty-one (68.9%) patients showed signs of cartilage degeneration on MRI at follow-up. The graft fixation with double biodegradable pin fixation appears to be a reliable technique for ACL reconstruction providing a stable close-to-joint graft fixation.

ACL reconstruction using the Rigidfix femoral fixation device via the anteromedial portal: a cadaver study to evaluate chondral injuries

The aim of this anatomic descriptive cadaver study is to evaluate the entrance points of cross-pins and the possible chondral damages, using a two cross-pin femoral fixation device via anteromedial portal, during anterior cruciate ligament (ACL) reconstruction. Twenty fresh-frozen cadaver knees (12 cadavers) were tested. We employed the Rigidfix Cross Pin device (Mitek, Norwood, MA), designed to use two biodegradable pins (PLA, length 42 mm, diameter 2.7 mm). Instead of PLA pins, we used color coded metallic pins. Femoral tunnel drilling and cross-pin guide insertions were performed through the anteromedial portal. We gave three positions to the cross-pin guide: 0 degrees , 45 degrees and 90 degrees slope, referring to the horizontal plane. Per each position, we inserted two metallic pins. We recorded and subdivided the pin holes, in three different groups: Group A (0 degrees ); B (45 degrees ); C (90 degrees of slope). Then a wide dissection has been implemented. Group A: 6 knees (30%) had two pins inside the cartilage of the lateral femoral condyle; 10 knees (50%) had one pin inside the cartilage; and 4 knees (20%) had both pins out of the cartilage. Group B: 7 knees (35%) had two pins inside the cartilage; 12 knees (60%) had one pin inside the cartilage; and one knee (5%) had both pins out of the cartilage. Group C: 7 knees (35%) had two pins inside the cartilage; and 13 knees (65%) had one pin inside the cartilage. The risk of chondral injury, using this technique, is high: from 80% (group A) to 100% (Group C) to have at least one pin inside the cartilage. The use of Rigidfix via AM portal is not recommended for routine ACL reconstruction.