Injuries to the quadriceps muscle group are common in athletes performing high-speed running and kicking sports. The complex anatomy of the rectus femoris puts it at greatest risk of injury. There is variability in prognosis in the literature, with reinjury rates as high as 67% in the severe graded proximal tear. Studies have highlighted that athletes can reinjure after nonoperative management, and some benefit may be derived from surgical repair to restore function and return to sport (RTS). This injury is potentially career-threatening in the elite-level athlete, and we aim to highlight the key recent literature on interventions to restore strength and function to allow early RTS while reducing the risk of injury recurrence. This article reviews the optimal diagnostic strategies and classification of quadriceps injuries. We highlight the unique anatomy of each injury on MRI and the outcomes of both nonoperative and operative treatment, providing an evidence-based management framework for athletes.

Cite this article: Bone Joint J 2023;105-B(12):1244–1251.

Aims

It has been established that mechanical stimulation benefits tendon-bone (T-B) healing, and macrophage phenotype can be regulated by mechanical cues; moreover, the interaction between macrophages and mesenchymal stem cells (MSCs) plays a fundamental role in tissue repair. This study aimed to investigate the role of macrophage-mediated MSC chondrogenesis in load-induced T-B healing in depth.

Aims

Achilles tendon re-rupture (ATRR) poses a significant risk of postoperative complication, even after a successful initial surgical repair. This study aimed to identify risk factors associated with Achilles tendon re-rupture following operative fixation.

In recent years, the plantaris tendon has been implicated in the development of chronic painful mid-portion Achilles tendinopathy. In some cases, a thickened plantaris tendon is closely associated with the Achilles tendon, and surgical excision of the plantaris tendon has been reported to be curative in patients who have not derived benefit following conservative treatment and surgical interventions. The aim of this review is to outline the basic aspects of, and the recent research findings, related to the plantaris tendon, covering anatomical and clinical studies including those dealing with histology, imaging and treatment. Cite this article: Bone Joint J 2016;98-B:1312–19

Aims. The purpose of this study was to identify the changes in untreated long head of the biceps brachii tendon (LHBT) after a rotator cuff tear and to evaluate the factors related to the changes. Methods. A cohort of 162 patients who underwent isolated supraspinatus with the preservation of LHBT was enrolled and evaluated. The cross-sectional area (CSA) of the LHBT on MRI was measured in the bicipital groove, and preoperative to postoperative difference was calculated at least 12 months postoperatively. Second, postoperative changes in the LHBT including intratendinous signal change, rupture, dislocation, or superior labral lesions were evaluated with seeking of factors that were correlated with the changes or newly developed lesions after rotator cuff repair. Results. The postoperative CSA (12.5 mm. 2. (SD 8.3) was significantly larger than preoperative CSA (11.5 mm. 2. (SD 7.5); p = 0.005). In total, 32 patients (19.8%) showed morphological changes in the untreated LHBT 24 months after rotator cuff repair. Univariate regression analysis revealed that the factor chiefly related to the change in LHBT status was an eccentric LHBT position within the groove found on preoperative MRI (p = 0.011). Multivariate analysis using logistic regression also revealed that an eccentric LHBT position was a factor related to postoperative change in untreated LHBTs (p = 0.011). Conclusion. The CSA of the LHBT inside the biceps groove increased after rotator cuff repair. The preoperative presence of an eccentrically positioned LHBT was associated with further changes of the tendon itself after rotator cuff repair. Cite this article: Bone Joint J 2020;102-B(9):1194–1199

Aims. Acute distal biceps tendon repair reduces fatigue-related pain and minimizes loss of supination of the forearm and strength of flexion of the elbow. We report the short- and long-term outcome following repair using fixation with a cortical button techqniue. Methods. Between October 2010 and July 2018, 102 patients with a mean age of 43 years (19 to 67), including 101 males, underwent distal biceps tendon repair less than six weeks after the injury, using cortical button fixation. The primary short-term outcome measure was the rate of complications. The primary long-term outcome measure was the abbreviated Disabilities of the Arm, Shoulder and Hand (QuickDASH) score. Secondary outcomes included the Oxford Elbow Score (OES), EuroQol five-dimension three-level score (EQ-5D-3L), satisfaction, and return to function. Results. Eight patients (7.8%) had a major complication and 34 (33.3%) had a minor complication. Major complications included re-rupture (n = 3; 2.9%), unrecovered nerve injury (n = 4; 3.9%), and surgery for heterotopic ossification (n = 1; 1.0%). Three patients (2.9%) overall required further surgery for a complication. Minor complications included neurapraxia (n = 27; 26.5%) and superficial infection (n = 7; 6.9%). A total of 33 nerve injuries occurred in 31 patients (30.4%). At a mean follow-up of five years (1 to 9.8) outcomes were available for 86 patients (84.3%). The median QuickDASH, OES, EQ-5D-3L, and satisfaction scores were 1.2 (IQR 0 to 5.1), 48 (IQR 46 to 48), 0.80 (IQR 0.72 to 1.0), and 100/100 (IQR 90 to 100), respectively. Most patients were able to return to work (81/83, 97.6%) and sport (51/62,82.3%). Unrecovered nerve injury was associated with an inferior outcome according to the QuickDASH (p = 0.005), OES (p = 0.004), EQ-5D-3L (p = 0.010), and satisfaction (p = 0.024). Multiple linear regression analysis identified an unrecovered nerve injury to be strongly associated with an inferior outcome according to the QuickDASH score (p < 0.001), along with infection (p < 0.001), although re-rupture (p = 0.440) and further surgery (p = 0.652) were not. Conclusion. Acute distal biceps tendon repair using cortical button fixation was found to result in excellent patient-reported outcomes and health-related quality of life. Although rare, unrecovered nerve injury adversely affects outcome. Cite this article: Bone Joint J 2021;103-B(7):1284–1291

Objectives. The objective of this study was to determine if the use of fascia lata as a tendon regeneration guide (placed into the tendon canal following harvesting the semitendinosus tendon) would improve the incidence of tissue regeneration and prevent fatty degeneration of the semitendinosus muscle. Materials and Methods. Bilateral semitendinosus tendons were harvested from rabbits using a tendon stripper. On the inducing graft (IG) side, the tendon canal and semitendinosus tibial attachment site were connected by the fascia lata, which was harvested at the same width as the semitendinosus tendon. On the control side, no special procedures were performed. Two groups of six rabbits were killed at post-operative weeks 4 and 8, respectively. In addition, three healthy rabbits were killed to obtain normal tissue. We evaluated the incidence of tendon tissue regeneration, cross-sectional area of the regenerated tendon tissue and proportion of fatty tissue in the semitendinosus muscle. Results. At post-operative week 8, the distal end of the regenerated tissue reached the vicinity of the tibial insertion on the control side in two of six specimens. On the IG side, the regenerated tissue maintained continuity with the tibial insertion in all specimens. The cross-sectional area of the IG side was significantly greater than that of the control side. The proportion of fatty tissue in the semitendinosus muscle on the IG side was comparable with that of the control side, but was significantly greater than that of the normal muscle. Conclusions. Tendon tissue regenerated with the fascia lata graft was thicker than naturally occurring regenerated tissue. However, the proportion of fatty tissue in the semitendinosus muscle was greater than that of normal muscle. Cite this article: K. Tabuchi, T. Soejima, H. Murakami, K. Noguchi, N. Shiba, K. Nagata. Inducement of tissue regeneration of harvested hamstring tendons in a rabbit model. Bone Joint Res 2016;5:247–252. DOI: 10.1302/2046-3758.56.2000585

Aims. The aim of this systematic review and meta-analysis is to evaluate differences in functional outcomes and complications between single- (SI) and double-incision (DI) techniques for the treatment of distal biceps tendon rupture. Methods. A comprehensive search on PubMed, MEDLINE, Scopus, and Cochrane Central databases was conducted to identify studies reporting comparative results of the SI versus the DI approach. The Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement was used for search strategy. Of 606 titles, 13 studies met the inclusion criteria; methodological quality was assessed with the Newcastle-Ottawa scale. Random- and fixed-effects models were used to find differences in outcomes between the two surgical approaches. The range of motion (ROM) and the Disabilities of the Arm, Shoulder and Hand (DASH) scores, as well as neurological and non-neurological complications, were assessed. Results. A total of 2,622 patients were identified. No significant differences in DASH score were detected between the techniques. The SI approach showed significantly greater ROM in flexion (standardized mean difference (SMD) -0.508; 95% confidence interval (CI) -0.904 to -0.112) and pronation (SMD -0.325, 95% CI -0.637 to -0.012). The DI technique was associated with significantly less risk of lateral antebrachial cutaneous nerve damage (odds ratio (OR) 4.239, 95% CI 2.171 to 8.278), but no differences were found for other nerves evaluated. The SI group showed significantly fewer events of heterotopic ossification (OR 0.430, 95% CI 0.226 to 0.816) and a lower reoperation rate (OR 0.503, 95% CI 0.317 to 0.798). Conclusion. No significant differences in functional scores can be expected between the SI and DI approaches after distal biceps tendon repair. The SI approach showed greater flexion and pronation ROM and a lower risk of heterotopic ossification and reoperation. The DI approach was favourable in terms of lower risk of neurological complications. Cite this article: Bone Joint J 2020;102-B(12):1608–1617

Objectives. The long head of the biceps (LHB) is often resected in shoulder surgery and could therefore serve as a cell source for tissue engineering approaches in the shoulder. However, whether it represents a suitable cell source for regenerative approaches, both in the inflamed and non-inflamed states, remains unclear. In the present study, inflamed and native human LHBs were comparatively characterized for features of regeneration. Methods. In total, 22 resected LHB tendons were classified into inflamed samples (n = 11) and non-inflamed samples (n = 11). Proliferation potential and specific marker gene expression of primary LHB-derived cell cultures were analyzed. Multipotentiality, including osteogenic, adipogenic, chondrogenic, and tenogenic differentiation potential of both groups were compared under respective lineage-specific culture conditions. Results. Inflammation does not seem to affect the proliferation rate of the isolated tendon-derived stem cells (TDSCs) and the tenogenic marker gene expression. Cells from both groups showed an equivalent osteogenic, adipogenic, chondrogenic and tenogenic differentiation potential in histology and real-time polymerase chain reaction (RT-PCR) analysis. Conclusion. These results suggest that the LHB tendon might be a suitable cell source for regenerative approaches, both in inflamed and non-inflamed states. The LHB with and without tendinitis has been characterized as a novel source of TDSCs, which might facilitate treatment of degeneration and induction of regeneration in shoulder surgery. Cite this article: J. Schmalzl, P. Plumhoff, F. Gilbert, F. Gohlke, C. Konrads, U. Brunner, F. Jakob, R. Ebert, A. F. Steinert. Tendon-derived stem cells from the long head of the biceps tendon: Inflammation does not affect the regenerative potential. Bone Joint Res 2019;8:414–424. DOI: 10.1302/2046-3758.89.BJR-2018-0214.R2

Aims. Functional rehabilitation has become an increasingly popular treatment for Achilles tendon rupture (ATR), providing comparably low re-rupture rates to surgery, while avoiding risks of surgical complications. Limited evidence exists on whether gap size should affect patient selection for this treatment option. The aim of this study was to assess if size of gap between ruptured tendon ends affects patient-reported outcome following ATR treated with functional rehabilitation. Methods. Analysis of prospectively collected data on all 131 patients diagnosed with ATR at Royal Berkshire Hospital, UK, from August 2016 to January 2019 and managed non-operatively was performed. Diagnosis was confirmed on all patients by dynamic ultrasound scanning and gap size measured with ankle in full plantarflexion. Functional rehabilitation using an established protocol was the preferred treatment. All non-operatively treated patients with completed Achilles Tendon Rupture Scores (ATRS) at a minimum of 12 months following injury were included. Results. In all, 82 patients with completed ATRS were included in the analysis. Their mean age was 51 years (standard deviation (SD) 14). The mean ATRS was 76 (SD 19) at a mean follow-up of 20 months (SD 11) following injury. Gap inversely affected ATRS with a Pearson’s correlation of -0.30 (p = 0.008). Mean ATRS was lower with gaps > 5 mm compared with ≤ 5 mm (73 (SD 21) vs 82 (SD 16); p = 0.031). Mean ATRS was lowest (70 (SD 23)) with gaps > 10 mm, with significant differences in perceived strength and pain. The overall re-rupture rate was two out of 131 (1.5%). Conclusion. Increasing gap size predicts lower patient-reported outcome, as measured by ATRS. Tendon gap > 5 mm may be a useful predictor in physically demanding individuals, and tendon gap > 10 mm for those with low physical demand. Further studies that control for gap size when comparing non-operative and operative treatment are required to assess if these patients may benefit from surgery, particularly when balanced against the surgical risks. Cite this article: Bone Joint J 2020;102-B(11):1535–1541

Flat foot due to rupture of the tibialis posterior tendon has not previously been described in children. We present three young patients who developed unilateral pes planus after old undiagnosed lacerations of the tendon. Transfer of the flexor hallucis longus to the distal stump of the tibialis posterior tendon achieved good results in all three cases

Aims. Since long-term outcome of teres major tendon transfer surgery for irreparable posterosuperior rotator cuff (RC) tears is largely unknown, the primary aim of this study was to evaluate the long-term outcome of the teres major transfer. We also aimed to report on the results of a cohort of patients with a similar indication for surgery that underwent a latissimus dorsi tendon transfer. Patients and Methods. In this prospective cohort study, we reported on the long-term results of 20 consecutive patients with a teres major tendon transfer for irreparable massive posterosuperior RC tears. Additionally, we reported on the results of the latissimus dorsi tendon transfer (n = 19). The mean age was 60 years (47 to 77). Outcomes included the Constant score (CS), and pain at rest and during movement using the Visual Analogue Scale (VAS). Results. At a mean of ten years (8 to 12) following teres major transfer, the CS was still 23 points (95% confidence interval (CI) 14.6 to 30.9, p < 0.001) higher than preoperatively. VAS for pain at rest (21 mm, 95% CI 4.0 to 38.9, p = 0.016) and movement (31 mm, 95% CI 16.0 to 45.1, p < 0.001) were lower than preoperatively. We also found an increase in CS (32 points, 95% CI 23.4 to 40.2, p < 0.001) and reduction of pain (26 mm, 95% CI 9.9 to 41.8, p = 0.001) six years after latissimus dorsi transfer. Conclusion. Teres major tendon transfer is a treatment option to gain shoulder function and reduce pain in patients with an irreparable posterosuperior RC tear at a mean follow-up of ten years. The teres major tendon might be a valuable alternative to the commonly performed latissimus dorsi tendon transfer in the treatment of irreparable posterosuperior RC tears. Cite this article: Bone Joint J 2018;100-B:309–17

Tendinopathy is a debilitating musculoskeletal condition which can cause significant pain and lead to complete rupture of the tendon, which often requires surgical repair. Due in part to the large spectrum of tendon pathologies, these disorders continue to be a clinical challenge. Animal models are often used in this field of research as they offer an attractive framework to examine the cascade of processes that occur throughout both tendon pathology and repair. This review discusses the structural, mechanical, and biological changes that occur throughout tendon pathology in animal models, as well as strategies for the improvement of tendon healing. Cite this article: Bone Joint Res 2014;3:193–202

We reviewed the records of 107 consecutive patients who had undergone surgery for disruption of the knee extensor mechanism to test whether an association existed between rupture of the quadriceps tendon and the presence of a patellar spur. The available standard pre-operative lateral radiographs were examined to see if a patellar spur was an indicator for rupture of the quadriceps tendon in this group of patients. Of the 107 patients, 12 underwent repair of a ruptured patellar tendon, 59 had an open reduction and internal fixation of a patellar fracture and 36 repair of a ruptured quadriceps tendon. In the 88 available lateral radiographs, patellar spurs were present significantly more commonly (p < 0.0005) in patients operated on for rupture of the quadriceps tendon (79%) than in patients with rupture of the patellar tendon (27%) or fracture of the patella (15%). In patients presenting with failure of the extensor mechanism of the knee in the presence of a patellar spur, rupture of the quadriceps tendon should be considered as a possible diagnosis

An understanding of the remodelling of tendon is crucial for the development of scientific methods of treatment and rehabilitation. This study tested the hypothesis that tendon adapts structurally in response to changes in functional loading. A novel model allowed manipulation of the mechanical environment of the patellar tendon in the presence of normal joint movement via the application of an adjustable external fixator mechanism between the patella and the tibia in sheep, while avoiding exposure of the patellar tendon itself. Stress shielding caused a significant reduction in the structural and material properties of stiffness (79%), ultimate load (69%), energy absorbed (61%), elastic modulus (76%) and ultimate stress (72%) of the tendon compared with controls. Compared with the material properties the structural properties exhibited better recovery after re-stressing with stiffness 97%, ultimate load 92%, energy absorbed 96%, elastic modulus 79% and ultimate stress 80%. The cross-sectional area of the re-stressed tendons was significantly greater than that of stress-shielded tendons. The remodelling phenomena exhibited in this study are consistent with a putative feedback mechanism under strain control. This study provides a basis from which to explore the interactions of tendon remodelling and mechanical environment

Little is known about the increase in length of tendons in postnatal life or of their response to limb lengthening procedures. A study was carried out in ten young and nine adult rabbits in which the tibia was lengthened by 20% at two rates 0.8 mm/day and 1.6 mm/day. The tendon of the flexor digitorum longus (FDL) muscle showed a significant increase in length in response to lengthening of the tibia. The young rabbits exhibited a significantly higher increase in length in the FDL tendon compared with the adults. There was no difference in the amount of lengthening of the FDL tendon at the different rates. Of the increase in length which occurred, 77% was in the proximal half of the tendon. This investigation demonstrated that tendons have the ability to lengthen during limb distraction. This occurred to a greater extent in the young who showed a higher proliferative response, suggesting that there may be less need for formal tendon lengthening in young children

Objectives. This study aimed to evaluate the histological and mechanical features of tendon healing in a rabbit model with second-harmonic-generation (SHG) imaging and tensile testing. Materials and Methods. A total of eight male Japanese white rabbits were used for this study. The flexor digitorum tendons in their right leg were sharply transected, and then were repaired by intratendinous stitching. At four weeks post-operatively, the rabbits were killed and the flexor digitorum tendons in both right and left legs were excised and used as specimens for tendon healing (n = 8) and control (n = 8), respectively. Each specimen was examined by SHG imaging, followed by tensile testing, and the results of the two testing modalities were assessed for correlation. Results. While the SHG light intensity of the healing tendon samples was significantly lower than that of the uninjured tendon samples, 2D Fourier transform SHG images showed a clear difference in collagen fibre structure between the uninjured and the healing samples, and among the healing samples. The mean intensity of the SHG image showed a moderate correlation (R. 2. = 0.37) with Young’s modulus obtained from the tensile testing. Conclusion. Our results indicate that SHG microscopy may be a potential indicator of tendon healing. Cite this article: E. Hase, K. Sato, D. Yonekura, T. Minamikawa, M. Takahashi, T. Yasui. Evaluation of the histological and mechanical features of tendon healing in a rabbit model with the use of second-harmonic-generation imaging and tensile testing. Bone Joint Res 2016;5:577–585. DOI: 10.1302/2046-3758.511.BJR-2016-0162.R1

Latissimus dorsi tendon transfer (LDTT) is technically challenging. In order to clarify the local structural anatomy, we undertook a morphometric study using six complete cadavers (12 shoulders). Measurements were made from the tendon to the nearby neurovascular structures with the arm in two positions: flexed and internally rotated, and adducted in neutral rotation. The tendon was then transferred and measurements were taken from the edge of the tendon to a reference point on the humeral head in order to assess the effect of a novel two-stage release on the excursion of the tendon. With the shoulder flexed and internally rotated, the mean distances between the superior tendon edge and the radial nerve, brachial artery, axillary nerve and posterior circumflex artery were 30 mm (26 to 34), 28 mm (17 to 39), 21 mm (12 to 28) and 15 mm (10 to 21), respectively. The mean distance between the inferior tendon edge and the radial nerve, brachial artery and profunda brachii artery was 18 mm (8 to 27), 22 mm (15 to 32) and 14 mm (7 to 21), respectively. Moving the arm to a neutral position reduced these distances. A mean of 15 mm (8 to 21) was gained from a standard soft-tissue release, and 32 mm (20 to 45) from an extensile release. These figures help to define further the structural anatomy of this region and the potential for transfer of the latissimus dorsi tendon. Cite this article: Bone Joint J 2013;95-B:517–22

We split 100 porcine flexor tendons into five groups of 20 tendons for repair. Three groups were repaired using the Pennington modified Kessler technique, the cruciate or the Savage technique, one using one new device per tendon and the other with two new devices per tendon. Half of the tendons received supplemental circumferential Silfverskiöld type B cross-stitch. The repairs were loaded to failure and a record made of their bulk, the force required to produce a 3 mm gap, the maximum force applied before failure and the stiffness. When only one device was used repairs were equivalent to the Pennington modified Kessler for all parameters except the force to produce a 3 mm gap when supplemented with a circumferential repair, which was equivalent to the cruciate. When two devices were used the repair strength was equivalent to the cruciate repair, and when the two-device repair was supplemented with a circumferential suture the force to produce a 3 mm gap was equivalent to that of the Savage six-strand technique

The piriformis muscle is an important landmark in the surgical anatomy of the hip, particularly the posterior approach for total hip replacement (THR). Standard orthopaedic teaching dictates that the tendon must be cut in to allow adequate access to the superior part of the acetabulum and the femoral medullary canal. However, in our experience a routine THR can be performed through a posterior approach without sacrificing this tendon. We dissected the proximal femora of 15 cadavers in order to clarify the morphological anatomy of the piriformis tendon. We confirmed that the tendon attaches on the crest of the greater trochanter, in a position superior to the trochanteric fossa, away from the entry point for broaching the intramedullary canal during THR. The tendon attachment site encompassed the summit and medial aspect of the greater trochanter as well as a variable attachment to the fibrous capsule of the hip joint. In addition we dissected seven cadavers resecting all posterior attachments except the piriformis muscle and tendon in order to study their relations to the hip joint, as the joint was flexed. At flexion of 90° the piriformis muscle lay directly posterior to the hip joint. The piriform fossa is a term used by orthopaedic surgeons to refer the trochanteric fossa and normally has no relation to the attachment site of the piriformis tendon. In hip flexion the piriformis lies directly behind the hip joint and might reasonably be considered to contribute to the stability of the joint. We conclude that the anatomy of the piriformis muscle is often inaccurately described in the current surgical literature and terms are used and interchanged inappropriately. Cite this article: Bone Joint J 2013;95-B:764–9