Hinge screw or no hinge stabilization provides decreased stability compared to hinge plate in a biomechanical evaluation of distal femoral derotational osteotomies.

PURPOSE: Derotational distal femoral osteotomy (DFO) is the causal treatment for patients with femoral torsional deformity. The fixation is achieved by a unilateral angle-stable plate. Delayed- or non-unions are one of the main risks of the procedure. An additional contralateral fixation may benefit the outcome. Therefore, we hypothesize that primary stability in DFO can be improved by an additional fixation with a hinge screw or an internal plate. METHODS: Derotational DFO was performed in 15 knees and fixed either with an angle-stable plate only (group 'None'), with an additional lateral screw (group 'Screw') or with an additional lateral plate (group 'Plate'). Biomechanical evaluation was carried out under axial loading of 150 N (partial weight bearing) and 800 N (full weight bearing), followed by internal and external rotation. After linear axial loading in step 1, a cyclic torsional load of 5 Nm was applied under constant axial load in step 2. In step 3, the specimens were unloaded. Micromovements between the distal and proximal parts of the osteotomy were recorded at each step for all specimens. RESULTS: In step 1, the extent of micromovements was highest in group 'None' and lowest in group 'Plate' without being significantly different. In step 2, group 'Plate' showed significantly higher stability, reflected by less rotation and lower micromovements. Increasing the axial load from 150 to 800 N at step 2 resulted in increased stability in all groups but only reached significance in group 'None'. CONCLUSION: An additional contralateral plate significantly increased stability in derotational DFO compared to the unilateral angle-stable plate only. Contrary, a contralateral hinge screw did not provide improved stability. STUDY DESIGN: Experimental study. LEVEL OF EVIDENCE: IV.

[Patient-specific cutting guides in corrective osteotomy near to the knee joint]. / Patientenspezifische Schnittblöcke bei kniegelenknahen Korrekturosteotomien.

OBJECTIVE: Patient-specific cutting guides (PSCG) are used in osteotomy near to the knee joint to simplify the operative technique, shorten the duration of surgery, reduce radiation exposure and to exactly realize the preoperative planning during surgery, especially when complex deformities are corrected simultaneously in multiple planes. INDICATIONS: The application of PSCG is in principle possible in all osteotomies near to the knee joint but is especially useful in multidimensional, complex osteotomy. CONTRAINDICATIONS: No specific contraindications. SURGICAL TECHNIQUE: After multidimensional 3D analysis and planning using a preoperative computed tomography (CT) protocol, a 3D-printed patient-specific cutting guide is produced. This PSCG is used during standard osteotomy near to the knee. Using this PSCG the guided sawcut and predrilling of the screw positions inside the bone for the screws of the planned angle stable osteotomy plate are performed. The amount of the deformity correction needed is "stored" in the PSCG and is converted to the bony geometry during placement of the screws in the predrilled holes through the plate after opening or closing the osteotomy. Apart from that, the surgical approach and technique are equivalent to the standard osteotomy types near to the knee. POSTOPERATIVE MANAGEMENT: The application of PSCG in osteotomy near to the knee does not change the postoperative management of the specific osteotomy. RESULTS: The use of patient-specific cutting guides leads to a higher accuracy in the implementation of the preoperative planning and the desired target axis is achieved with greater accuracy. Multidimensional complex corrections can also be exactly planned and implemented. In addition, the intraoperative radiation exposure for the operation team can possibly be reduced.

Comparison of two joint-preserving treatments for osteonecrosis of the femoral head: core decompression and core decompression with additional cancellous bone grafting.

OBJECTIVE: Femoral head necrosis (FHN) affects mostly young and active people. The most common operative therapy is core decompression (CD) with optional cancellous bone grafting (CBG). Because little information is available on the long-term results of these procedures, we investigated the effectiveness of CD and CD + CBG in patients with ARCO stage II FHN in terms of postoperative pain, range of motion, patient-reported outcome measures (Harris Hip Score, Hip Disability and Osteoarthritis Outcome Score, EuroQol 5D, and Short Form 36 Questionnaire), and disease progression. METHODS: We retrospectively compared 11 patients treated with CD alone 48.0 months (range, 26.3-68.5 months) postoperatively versus 11 patients treated with CD + CBG 69.2 months (range, 38.0-92.9 months) postoperatively. All patients were assessed according to a routine clinical protocol involving a clinical examination, questionnaires, and radiological imaging (X-ray and magnetic resonance imaging). RESULTS: The clinical and radiological results showed no significant differences between the two groups. Both interventions demonstrated equal results according to clinical scores. CONCLUSIONS: Our data may encourage application of the less invasive technique of CD alone without CBG, which is more surgically demanding. Further prospective studies with longer follow-up are necessary to clarify the risk factors for therapy failure.

Intraoperative control by Schanz-screws is inaccurate to achieve the exact amount of correction in de-rotational osteotomies.

PURPOSE: The accuracy of intraoperative control of correction commonly is achieved by K-wires or Schanz-screws in combination with goniometer in de-rotational osteotomies. The purpose of this study is to investigate the accuracy of intraoperative torsional control in de-rotational femoral and tibial osteotomies. It is hypothesized, that intraoperative control by Schanz-screws and goniometer in de-rotational osteotomies around the knee is a safe and well predictable method to control the surgical torsional correction intraoperatively. METHODS: 55 consecutive osteotomies around the knee joint were registered, 28 femoral and 27 tibial. The indication for osteotomy was femoral or tibial torsional deformity with the clinical occurrence of patellofemoral maltracking or PFI. Pre- and postoperative torsions were measured according to the method of Waidelich on computed tomography (CT) scan. The scheduled value of torsional correction was defined by the surgeon preoperatively. Intraoperative control of torsional correction was achieved by 5 mm-Schanz-screws and goniometer. The measured values of torsional CT scan were compared to the preoperative defined and intended values and deviation was calculated separately for femoral and tibial osteotomies. RESULTS: The surgeon's intraoperative measured mean value of correction in all osteotomies was 15.2° (SD 4.6; range 10-27), whereas the postoperatively measured mean value on CT scan was 15.6 (6.8; 5.0-28.5). Intraoperatively the femoral mean value measured 17.9° (4.9; 10-27) and 12.4° (1.9; 10-15) for the tibia. Postoperatively the mean value for femoral correction was 19.8 (5.5; 9.0-28.5) and 11.3 (5.0; 5.0-26.0) for tibial correction. When considering a deviation of plus or minus 3° to be acceptable femorally 15 osteotomies (53.6%) and tibially 14 osteotomies (51.9%) fell within these limits. Nine femoral cases (32.1.%) were overcorrected, four cases undercorrected (14.3%). Four tibial cases of overcorrection (14.8%) and 9 tibial cases of undercorrection (33.3%) were observed. However, the observed difference between femur and tibia regarding the distribution of cases between the three groups did not reach significance. Moreover, there was no correlation between the extent of correction and the deviation from the intended result. CONCLUSION: The use of Schanz-screws and goniometer in de-rotational osteotomies as an intraoperative control of correction is an inaccurate method. Every surgeon performing derotational osteotomies must consider this and include postoperative torsional measurement in his postoperative algorithm until new tools or devices are available to guarantee a better intraoperative accuracy of torsional correction. STUDY DESIGN: Observational study. LEVEL OF EVIDENCE: III.

Avascular necrosis of the femoral head: three-dimensional measurement of drilling precision reveals high accuracy and no difference between fluoroscopically controlled core decompression and cancellous bone grafting.

INTRODUCTION: Avascular osteonecrosis of the femoral head (AVN) is a widespread disease affecting mostly young and active people, often exacerbating in progressive stages, ending in joint replacement. The most common joint preserving operative therapy for early stages is core decompression (CD), optional with cancellous bone grafting (CBG). For success it is vital that the necrotic area is hit and the sclerotic rim is broken by drilling into the defect zone to relieve intraosseous pressure. The aim of this study was to investigate if both techniques are precise enough to hit the center of the necrosis and if there is a difference in precision between drilling with small pins (CD) and the trephine (CBG). PATIENTS AND METHODS: 10 patients underwent CD, 12 patients CBG with conventional C-arm imaging. Postoperatively 3D MRI reconstructions of the necrotic area and the drilling channels were compared. The deviation of the drilling channel from the center of the necrotic area was measured. PROMs (HHS, HOOS, EQ-5D, SF-36) were evaluated to compare the clinical success of these procedures. RESULTS: Neither with CD nor with CBG the defect zone was missed. The drilling precision of both procedures did not differ significantly: distance to center 3.58 mm for CD (range 0.0-14.06, SD 4.2) versus 3.91 mm for CBG (range 0.0-15.27, SD 4.7). PROMs showed no significant difference. CONCLUSION: Concerning the most important difference between the two procedures-the surgical higher demanding technique of CBG-we suggest applying the less invasive technique of CD alone.

Correction of tibial tubercle trochlea groove distance is related to torsional correction in high tibial derotational osteotomy.

PURPOSE: High tibial osteotomy with internal tibial derotation (high tibial derotation osteotomy = HTDRO) is a common surgical treatment in patients with patellofemoral malalignment alone or in combination with patellofemoral instability. Operative techniques and theoretical calculations may assume that correction of the tibial tubercle-trochlear groove (TTTG) distance is related to the amount of torsional correction. The purpose of this investigation was to predict the change in TTTG distance in HTDRO through a clinical study. METHODS: Twenty-one consecutive cases of derotational HTO were evaluated by torsional CT scanning in terms of the pre- and postoperative tibial torsion and TTTG distance. Changes in the TTTG distance were related to the changes in the amount of torsional correction. The change in patellar height was measured pre- and postoperatively, and the Caton-Deschamps Index (CDI) was calculated. RESULTS: The mean change in tibial torsion was 13.9°, and the mean change in the TTTG distance was 6.3 mm. A strong relationship (0.90) between the change in torsion and the change in TTTG distance from pre- to postoperative status was found (p < 0.001). No statistically significant change in CDI could be seen between the preoperative [mean value (MV) 1.0] and postoperative (MV 1.1) periods. CONCLUSIONS: In patients with patellofemoral instability or patellofemoral maltracking with both a high tibial external torsion and a high TTTG distance, a derotational HTO can correct both bony deformities. Patella height does not change significantly with this surgical technique. With 1° of torsional correction, the TTTG distance decreases 0.45 mm with our surgical technique of derotational HTO.

Significant slope reduction in ACL deficiency can be achieved both by anterior closing-wedge and medial open-wedge high tibial osteotomies: early experiences in 76 cases.

PURPOSE: It has been proven that a steep tibial slope (TS) is a risk factor for anterior cruciate ligament (ACL) injury and graft insufficiency after ACL reconstruction (ACLR). Recently, there is an increasing number of case series on slope decreasing osteotomies after failed ACLR utilizing different techniques and strategies. Goal of the present study is to report on early experiences with slope decreasing osteotomies in ACL deficient knees with special emphasis on the amount of slope correction, technical details, and complications; and to further analyze differences of slope corrections between sole sagittal as well as combined coronal and sagittal realignment procedures. In addition, we wanted to study if sole sagittal corrections change the coronal alignment. METHODS: Seventy-six patients with a minimum follow-up of 6 months were identified, who underwent a sole sagittal correction (anterior closed-wedge high tibial osteotomy (ACW-HTO)) or a combined procedure with an additional coronal realignment (medial open-wedge high tibial osteotomy (MOW-HTO)). In ACW-HTO, either infratuberosity or supratuberosity approaches were used. The medial TS was measured on lateral radiographs and the anatomical medial proximal tibial angle (aMPTA) was measured on anterior-posterior radiographs. Technical details and specific complications were recorded. RESULTS: Fifty-eight ACW-HTO and 18 MOW-HTO were performed. Regarding ACW-HTO, an infratuberosity (N = 48) or a supratuberosity (N = 10) approach was chosen. Sixty-seven patients had at least 1 previous ACLR. Mean TS changed from 14.5 ± 2.2° to 6.8 ± 1.9° (P < 0.0001). Mean TS of ACW-HTO was significantly reduced (14.6 ± 2.3° vs. 6.5 ± 1.9°; P < 0.0001), whereas in combined coronal and sagittal realignments, from 14.1 ± 1.9° to 7.6 ± 1.9° (P < 0.0001). The TS reduction in sole sagittal corrections was significantly higher compared to combined procedures (8.1 ± 1.6 vs. 6.4 ± 1.6°; P = 0.0002). Mean aMPTA in ACW-HTO changed from 87.1 ± 2.1° to 87.4 ± 2.8 (n.s.). However, there was a significant inverse correlation between the amount of sagittal correction and coronal alteration (r = - 0.29; P = 0.028). There was one late implant infection, which occurred 5.5 months after the index surgery. CONCLUSIONS: ACW-HTO and MOW-HTO facilitate significant slope reduction with a low-risk profile in patients with ACL insufficiency and a high tibial slope. AOW-HTO does not significantly alter coronal alignment in the majority of patients. LEVEL OF EVIDENCE: IV.

Perioperative complications in osteotomies around the knee: a study in 858 cases.

INTRODUCTION: Eight hundred and fifty-eight consecutive osteotomies around the knee joint were analyzed retrospectively to detect intra- and early postoperative complications in a period of 4 weeks postoperative. Indications for osteotomy were unilateral gonarthritis or torsional deformities resulting in femoropatellar instability or anterior knee pain. MATERIALS AND METHODS: Etiology of deformity, technique and mode of correction and level of osteotomy were registered. Complications were detected and divided in minor complication (superficial wound infection, and deep-vein thrombosis) and major complication (compartment syndrome, deep infection, and vascular lesion). RESULTS: Fifteen major (1.7%) and 17 minor complications (2.0%) were detected: 5 vascular lesions (0.58%), 4 compartment syndromes (0.47%) and 6 deep infections (0.70%), 14 superficial wound infections (1.6%) and 3 deep-vein thrombosis (0.35%). In posttraumatic osteotomies and continuous corrections, risk for a superficial wound infection was significantly higher and with osteoclasia risk for vascular lesion was higher compared to osteotomy with oscillating saw. No difference was found for anatomical level of osteotomy and for the other complications in terms of etiology of deformity, technique of osteotomy and mode of correction. CONCLUSION: Osteotomy around the knee is a safe procedure in the treatment of unicompartmental gonarthritis in terms of intra- and postoperative complications. Major complications are rare. Pit falls for compartment syndromes (LCW and torsional corrections) have to kept in mind. There is no difference in frequency of complications between HTO and supracondylar osteotomies. Risk for superficial wound infection is higher in posttraumatic osteotomies and with continuous corrections. Osteoclasia contains a higher risk for vascular lesion compared to oscillating saw.

[Retrograde bone transport nail in a posttraumatic femoral bone defect]. / Retrograder Femursegmenttransportnagel ­ eine Anwendung bei posttraumatischem Knochendefekt mit Komplexdeformität.

We report the case of a 28-year-old man who developed nonunion with complex deformity after treatment of a distal femoral fracture with an antegrade femoral nail. The resulting deformity was as follows: 10° varus, 21° external torsion, 1.8 cm of foreshortening and translation malalignment. After resection of the pseudarthrosis, a retrograde segmental transport nail was implanted. During the same surgical procedure, acute internal torsion, valgization and lengthening correction was performed. The segment transport was performed using a magnetically driven internal transport nail. Seven months after surgery, bony consolidation of the distraction section and the docking site was observed. The leg axis was straight and the rotational movement ranges of the knee and hip corresponded the dimensions of the contralateral side.

The effect of open-wedge and closed-wedge high tibial osteotomies on the tibial posterior slope-a study of two hundred seventy-nine cases.

PURPOSE: There are two established techniques for high tibial valgisation osteotomy (HTO): medial open wedge (MOW) and lateral closed wedge (LCW). The aim was to analyze the change of the posterior tibial slope (PTS) caused by HTOs dependent on the technique. METHODS: Four hundred fourteen cases of HTOs were analyzed retrospectively. Two hundred seventy-nine osteotomies in 247 patients matched the inclusion criteria and were divided into two treatment groups (MOW/LCW). The PTS was determined on pre- and post-surgical lateral knee X-rays by measuring the proximal posterior tibial angle (PPTA). RESULTS: One hundred ninety of the included 279 cases were assigned to the MOW and 89 to the LCW group. The mean PPTA in MOW HTOs was 79.9° ± 32° (68-88°) and in LCW HTOs 80.6° ± 2.6° (74-88°). There was no statistically significant change of the PPTA in the MOW group comparing the pre- and post-surgical values (delta PPTA 0.07° ±2.9° (- 12 to 11°)). In the LCW group, the surgery resulted in a statistically significant reduction (p< 0.001) of the PTS (delta PPTA - 3.09° ± 4.5° (- 12 to 5°)). CONCLUSION: The important finding of this study is that the thesis of a slope increase in MOW osteotomies found in the literature could not be approved regarding our results as no statistically significant change of PTS in MOW HTOs was observed. The findings support the common thesis that LCW osteotomies cause a slope reduction.

Medial open wedge vs. lateral closed wedge high tibial osteotomy - Indications based on the findings of patellar height, leg length, torsional correction and clinical outcome in one hundred cases.

INTRODUCTION: Medial open wedge (MOW) and lateral closed wedge (LCW) osteotomies are established methods to treat medial gonarthritis. Advantages and differences in the outcome of the two techniques have been discussed controversially and there is still no precise recommendation for either technique. We now aimed to assess the effect of each technique on tibial slope (TS), patella height (PH) and leg length discrepancy. METHOD: In a study of 50 consecutive cases of MOW and 50 of LCW osteotomies were registered. The decision for either technique was made pre-operatively according to an algorithm. Demographic data, operation procedures (time of operation, correction angle, torsional correction) and measurement of patellar height, tibial slope, leg length discrepancy, clinical outcome after one year and bone and wound healing were obtained. Pre- and post-operative values were compared between the two groups. RESULTS: In absence of randomization demographic data demonstrate comparability of the two groups. No difference in bone and wound healing, time of operation and clinical outcome was seen. In the MOW group PH decreased significantly, no relevant alteration of PH was detected in the LCW group. In the latter group a statistically significant decrease of TS compared to a slightly decrease in the MOW group was recorded post-operatively. A significant leg lengthening with the MOW and shortening of the leg with the LCW method can be achieved. DISCUSSION: With respect to similar results in operating procedures, bone and wound healing and clinical outcome decision making factors for either technique should be leg length discrepancy and torsional deformities. Changes of PH and TS have to be known and may influence the technique of osteotomy in cases of patella infera / alta or borderline PH. CONCLUSION: An algorithm for valgus high tibial osteotomies based on TS, PH and leg length discrepancy may be proposed.

Patellofemoral dysbalance and genua valga: outcome after femoral varisation osteotomies.

INTRODUCTION: Patellofemoral dysbalance may be caused by trochlear dysplasia, an elevated TTTG distance, femoral or tibial torsional deformities, patella alta, or a genu valgum. The surgical procedure for the treatment of a genu valgum is varisation osteotomy, usually in the femoral aspect. Several authors believe that a genu valgum is one cause of patellofemoral dysbalance, but studies about the outcome of the treatment with a varisation osteotomy are rare. MATERIALS AND METHODS: Nineteen knees in 18 patients, aged on average 28 (16-52) years were investigated in a retrospective study. The patients had symptoms of patellofemoral instability or anterior knee pain due to a genu valgum, without symptoms of a lateral femorotibial compartment. All patients underwent a femoral varisation osteotomy. The diagnostic investigation prior to surgery included full-leg radiographs and torsional angle CT scans. The pre-surgery and follow-up investigation included the visual analog scale (VAS), the Kujala score, the Japanese Knee Society score, the Lysholm score. RESULTS: The mean duration of follow-up was 44(10-132) months. The mean preoperative mechanical valgus was 5.6° (range 4-10°). Twelve patients mentioned patellar instability as the main symptom while 14 mentioned anterior knee pain. No redislocation occurred in the follow-up period. Anterior knee pain on the VAS (p value < 0.001) was significantly reduced (5.6-2.1). The Japanese Knee Society score improved from 87 to 93 (p value 0.013) points, the Kujala score improved significantly from 72 to 87 (p value 0.009), and the Lysholm score significantly from 76 to 92 (p value < 0.001). CONCLUSION: Genua valga can lead to patellofemoral dysbalance, treatment of this condition is femoral varisation osteotomy. In this study, patellofemoral stability was achieved and anterior knee pain was significantly reduced. Significant improvements in clinical scores proved the success of the treatment. LEVEL OF EVIDENCE: IV, case series.

Is a synthetic augmentation in medial open wedge high tibial osteotomies superior to no augmentation in terms of bone-healing?

INTRODUCTION: Medial open-wedge high tibial osteotomy (MOWHTO) is an established method to treat unicompartimental osteoarthritis of the knee joint. However, augmentation of the created tibial gap after osteotomy is controversially discussed. METHODS: We performed a prospective investigation of 49 consecutive cases of MOWHTO at our department. Patients were divided into two groups: group A consisted of 19 patients while group B consisted of 30 patients. In group A, the augmentation of the opening gap after osteotomy was filled with a synthetic bone graft, whereas group B received no augmentation. As an indicator for bone healing we investigated the non-union rate in our study population and compared the non-union-rate between the two groups. RESULTS: The non-union rate was 28% in group A (five of 19 patients had to undergo revision) which received synthetic augmentation, while it was 3.3% in group B (one of 30 patients had to undergo revision) which received no augmentation. The difference between the groups was statistically significant (p-value 0.027). CONCLUSIONS: With regard to bone healing after MOWHTO, synthetic augmentation was not superior to no augmentation in terms of non-union rates after surgery. In fact, we registered a significantly higher rate of non-union after augmentation with synthetic bone graft. LEVEL OF EVIDENCE: III.